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Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2021	Jan. 21, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Goodwill			$ 14,551	$ 14,562	$ 13,526
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividend declared date		Jan. 21, 2021
Quarterly dividend payable, per share		$ 4.13
Dividend payable date		Mar. 23, 2021
Dividend payable, record date		Mar. 05, 2021
Subsequent Event [Member] \| Aperio [Member]
Subsequent Event [Line Items]
Business acquisition, percentage of equity interest acquired	100.00%
Payments to acquire business	$ 1,100
Goodwill	800
Goodwill, expected to be deductible for tax purposes	500
Subsequent Event [Member] \| Aperio [Member] \| Customer Relationships [Member]
Subsequent Event [Line Items]
Finite-lived intangible assets	$ 300
Weighted-average estimated life	10 years
Subsequent Event [Member] \| Aperio [Member] \| Customer Relationships [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Estimated life	10 years
Subsequent Event [Member] \| Aperio [Member] \| Customer Relationships [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Estimated life	12 years