Investment Securities (Tables)

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of AFS Securities

The following tables summarize the Company's AFS and HTM securities:

December 31, 2019 (Dollars in millions)	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
AFS securities:
U.S. Treasury	$	2,275	$	7	$	6	$	2,276
GSE	1,847		34		—		1,881
Agency MBS - residential	67,983		411		158		68,236
Agency MBS - commercial	1,335		13		7		1,341
States and political subdivisions	557		34		6		585
Non-agency MBS	190		178		—		368
Other	40		—		—		40
Total AFS securities	$	74,227	$	677	$	177	$	74,727
December 31, 2018 (Dollars in millions)	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
AFS securities:
U.S. Treasury	$	3,503	$	22	$	84	$	3,441
GSE	209		—		9		200
Agency MBS - residential	20,170		15		759		19,426
Agency MBS - commercial	757		—		28		729
States and political subdivisions	694		25		18		701
Non-agency MBS	321		184		—		505
Other	35		1		—		36
Total AFS securities	$	25,689	$	247	$	898	$	25,038
HTM securities:
U.S. Treasury	$	1,099	$	—	$	6	$	1,093
GSE	2,199		4		43		2,160
Agency MBS - residential	17,248		27		487		16,788
States and political subdivisions	5		—		—		5
Other	1		—		—		1
Total HTM securities	$	20,552	$	31	$	536	$	20,047

Summary of HTM Securities

The following tables summarize the Company's AFS and HTM securities:

December 31, 2019 (Dollars in millions)	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
AFS securities:
U.S. Treasury	$	2,275	$	7	$	6	$	2,276
GSE	1,847		34		—		1,881
Agency MBS - residential	67,983		411		158		68,236
Agency MBS - commercial	1,335		13		7		1,341
States and political subdivisions	557		34		6		585
Non-agency MBS	190		178		—		368
Other	40		—		—		40
Total AFS securities	$	74,227	$	677	$	177	$	74,727
December 31, 2018 (Dollars in millions)	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
AFS securities:
U.S. Treasury	$	3,503	$	22	$	84	$	3,441
GSE	209		—		9		200
Agency MBS - residential	20,170		15		759		19,426
Agency MBS - commercial	757		—		28		729
States and political subdivisions	694		25		18		701
Non-agency MBS	321		184		—		505
Other	35		1		—		36
Total AFS securities	$	25,689	$	247	$	898	$	25,038
HTM securities:
U.S. Treasury	$	1,099	$	—	$	6	$	1,093
GSE	2,199		4		43		2,160
Agency MBS - residential	17,248		27		487		16,788
States and political subdivisions	5		—		—		5
Other	1		—		—		1
Total HTM securities	$	20,552	$	31	$	536	$	20,047

Schedule of Amortized Cost and Estimated Fair Value by Contractual Maturity

The amortized cost and estimated fair value of the securities portfolio by contractual maturity are shown in the following table. The expected life of MBS may differ from contractual maturities because borrowers may have the right to prepay their obligations with or without penalties.

	Amortized Cost										Fair Value
December 31, 2019 (Dollars in millions)	Due in one year or less		Due after one year through five years		Due after five years through ten years		Due after ten years		Total		Due in one year or less		Due after one year through five years		Due after five years through ten years		Due after ten years		Total
AFS securities:
U.S. Treasury	$	1,360	$	899	$	16	$	—	$	2,275	$	1,367	$	893	$	16	$	—	$	2,276
GSE	—		1,768		—		79		1,847		—		1,800		—		81		1,881
Agency MBS - residential	—		1		552		67,430		67,983		—		1		554		67,681		68,236
Agency MBS - commercial	—		2		9		1,324		1,335		—		1		10		1,330		1,341
States and political subdivisions	35		97		215		210		557		35		100		226		224		585
Non-agency MBS	—		—		—		190		190		—		—		—		368		368
Other	2		7		1		30		40		2		7		1		30		40
Total AFS securities	$	1,397	$	2,774	$	793	$	69,263	$	74,227	$	1,404	$	2,802	$	807	$	69,714	$	74,727

Schedule of Fair Values and Gross Unrealized Losses

The following tables present the fair values and gross unrealized losses of investments based on the length of time that individual securities have been in a continuous unrealized loss position:

	Less than 12 months				12 months or more				Total
December 31, 2019 (Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
AFS securities:
U.S. Treasury	$	702	$	6	$	—	$	—	$	702	$	6
GSE	6		—		—		—		6		—
Agency MBS - residential	20,328		145		1,326		13		21,654		158
Agency MBS - commercial	545		5		124		2		669		7
States and political subdivisions	65		1		144		5		209		6
Total	$	21,646	$	157	$	1,594	$	20	$	23,240	$	177
	Less than 12 months				12 months or more				Total
December 31, 2018 (Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
AFS securities:
U.S. Treasury	$	111	$	—	$	2,121	$	84	$	2,232	$	84
GSE	3		—		176		9		179		9
Agency MBS - residential	222		—		17,892		758		18,114		758
Agency MBS - commercial	100		2		586		27		686		29
States and political subdivisions	100		1		288		17		388		18
Total	$	536	$	3	$	21,063	$	895	$	21,599	$	898
HTM securities:
U.S. Treasury	$	698	$	3	$	395	$	3	$	1,093	$	6
GSE	—		—		1,749		43		1,749		43
Agency MBS - residential	264		3		14,976		484		15,240		487
Total	$	962	$	6	$	17,120	$	530	$	18,082	$	536

Schedule of Realized Gain (Loss)

The following table presents gross securities gains and losses recognized in earnings:

Year Ended December 31, (Dollars in millions)	2019		2018		2017
Gross realized gains	$	47	$	4	$	17
Gross realized losses	(163)		(1)		(18)
Securities gains (losses), net	$	(116)	$	3	$	(1)