HTM Debt Securities, Contractual Maturities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 204,080	$ 208,023
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	97
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	2,230
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	4,399
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	197,354
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	171,298	175,797
Held-to-maturity, fair value, remaining contractual maturity, due within one year	99
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	2,237
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	4,391
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 164,571
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.44%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	1.08%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	4.74%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	5.01%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.36%
AFS and HTM Debt Securities Textual [Abstract]
Debt securities, held-to-maturity, amortized cost, after allowance for credit loss, maturity allocation basis [Extensible Enumeration]	Debt Securities, Maturity Allocation, Contractual Maturity [Member]
Securities of U.S. Treasury and federal agencies [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 3,799	3,797
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	3,799
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	2,032	2,050
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 2,032
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	1.60%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	1.60%
Securities of U.S. states and political subdivisions [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 17,400	17,476
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	89
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	427
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	436
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	16,448
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	13,930	14,208
Held-to-maturity, fair value, remaining contractual maturity, due within one year	88
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	419
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	417
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 13,006
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.52%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.94%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	2.33%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	2.67%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.53%
Federal agency mortgage-backed securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 175,626	178,882
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	175,626
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	148,031	151,608
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 148,031
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.34%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.34%
Non-agency mortgage-backed securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 1,522	1,497
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	8
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	11
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	22
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	1,481
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	1,554	1,540
Held-to-maturity, fair value, remaining contractual maturity, due within one year	11
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	17
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	24
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 1,502
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	3.82%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	2.47%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	6.24%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	2.75%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	3.82%
Collateralized loan obligations [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 4,016	4,655
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	75
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	3,941
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	0
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	4,026	4,674
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	76
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	3,950
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 0
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	5.30%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	5.84%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	5.29%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	0.00%
Other debt securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 1,717	1,716
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	1,717
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	0
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	1,725	$ 1,717
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	1,725
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 0
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	5.27%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	5.27%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	0.00%

Amount excluding accrued interest, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity) with single maturity date and allocated without single maturity date, maturing after rolling tenth fiscal year following current statement of financial position date. For interim and annual periods when interim period is reported on rolling approach.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477268/942-320-50-3