Debt Securities (Tables)

The amortized cost, gross unrealized gains and losses, and estimated fair value of debt securities held to maturity and debt securities available for sale are as follows:


	December 31, 2021
			Recognized in OCI (1)						Not recognized in OCI
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Carrying Value		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In millions)
Debt securities held to maturity:


Mortgage-backed securities:
Residential agency	$	370	$	—	$	(13)	$	357	$	20	$	—	$	377
Commercial agency	543		—		(1)		542		31		—		573
	$	913	$	—	$	(14)	$	899	$	51	$	—	$	950

Debt securities available for sale:
U.S. Treasury securities	$	1,137	$	2	$	(7)	$	1,132					$	1,132
Federal agency securities	94		1		(3)		92						92
Obligations of states and political subdivisions	4		—		—		4						4
Mortgage-backed securities:
Residential agency	18,873		287		(198)		18,962						18,962
Residential non-agency	1		—		—		1						1
Commercial agency	6,271		163		(61)		6,373						6,373
Commercial non-agency	532		4		—		536						536
Corporate and other debt securities	1,351		36		(6)		1,381						1,381
	$	28,263	$	493	$	(275)	$	28,481					$	28,481


	December 31, 2020
			Recognized in OCI (1)						Not recognized in OCI
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Carrying Value		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In millions)
Debt securities held to maturity:


Mortgage-backed securities:
Residential agency	$	554	$	—	$	(19)	$	535	$	34	$	—	$	569
Commercial agency	589		—		(2)		587		59		—		646
	$	1,143	$	—	$	(21)	$	1,122	$	93	$	—	$	1,215

Debt securities available for sale:
U.S. Treasury securities	$	178	$	5	$	—	$	183					$	183
Federal agency securities	102		3		—		105						105

Mortgage-backed securities:
Residential agency	18,455		625		(4)		19,076						19,076
Residential non-agency	1		—		—		1						1
Commercial agency	5,659		346		(6)		5,999						5,999
Commercial non-agency	571		15		—		586						586
Corporate and other debt securities	1,126		78		—		1,204						1,204
	$	26,092	$	1,072	$	(10)	$	27,154					$	27,154

(1)The gross unrealized losses recognized in OCI on securities held to maturity resulted from a transfer of securities available for sale to held to maturity in the second quarter of 2013.

The amortized cost and estimated fair value of debt securities held to maturity and debt securities available for sale at December 31, 2021, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.


	Amortized Cost		Estimated Fair Value
	(In millions)
Debt securities held to maturity:
Mortgage-backed securities:
Residential agency	$	370	$	377
Commercial agency	543		573
	$	913	$	950
Debt securities available for sale:
Due in one year or less	$	325	$	328
Due after one year through five years	1,289		1,304
Due after five years through ten years	855		860
Due after ten years	117		117
Mortgage-backed securities:
Residential agency	18,873		18,962
Residential non-agency	1		1
Commercial agency	6,271		6,373
Commercial non-agency	532		536
	$	28,263	$	28,481

The following tables present gross unrealized losses and the related estimated fair value of debt securities available for sale at December 31, 2021 and 2020. These securities are segregated between investments that have been in a continuous unrealized loss position for less than twelve months and for twelve months or more.


	December 31, 2021
	Less Than Twelve Months				Twelve Months or More				Total
	Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses
	(In millions)







Debt securities available for sale:
U.S Treasury securities	$	1,010	$	(7)	$	—	$	—	$	1,010	$	(7)
Federal agency securities	63		(3)		—		—		63		(3)
Mortgage-backed securities:
Residential agency	$	9,528	$	(171)	$	686	$	(27)	$	10,214	$	(198)

Commercial agency	1,333		(29)		760		(32)		2,093		(61)

Corporate and other debt securities	444		(6)		—		—		444		(6)
	$	12,378	$	(216)	$	1,446	$	(59)	$	13,824	$	(275)


	December 31, 2020
	Less Than Twelve Months				Twelve Months or More				Total
	Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses
	(In millions)







Debt securities available for sale:


Mortgage-backed securities:
Residential agency	$	914	$	(4)	$	101	$	—	$	1,015	$	(4)

Commercial agency	819		(6)		—		—		819		(6)


	$	1,733	$	(10)	$	101	$	—	$	1,834	$	(10)

Gross realized gains and gross realized losses on sales of debt securities available for sale were immaterial for both 2021 and 2020, and are shown in the table below for 2019. The cost of securities sold is based on the specific identification method. As part of the Company's normal process for evaluating impairment, management did identify a limited number of positions where impairment was believed to exist in 2019, as shown in the table below.


	Year Ended December 31
	2019
	(In millions)
Gross realized gains	$	16
Gross realized losses	(43)
Impairment	(1)
Securities gains (losses), net	$	(28)