Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses, and Fair Values of Securities

At December 31, 2018 and 2017, the amortized cost, gross unrealized gains, gross unrealized losses and fair values of securities available for sale are presented below.

	December 31, 2018
(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Asset Liability Management securities:
U.S. Treasury	$	3,572	$	1	$	144	$	3,429
Residential mortgage-backed securities:
U.S. government agency and government-sponsored agencies	8,168		7		168		8,007
Privately issued	887		—		23		864
Privately issued - commercial mortgage-backed securities	1,179		3		20		1,162
Collateralized loan obligations	1,492		—		18		1,474
Other	4		—		—		4
Asset Liability Management securities	15,302		11		373		14,940
Other debt securities:
Direct bank purchase bonds	1,190		30		30		1,190
Other	188		—		4		184
Total securities available for sale	$	16,680	$	41	$	407	$	16,314

	December 31, 2017
(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Asset Liability Management securities:
U.S. Treasury	$	3,370	$	—	$	118	$	3,252
Residential mortgage-backed securities:
U.S. government agency and government-sponsored agencies	9,338		2		132		9,208
Privately issued	695		3		4		694
Privately issued - commercial mortgage-backed securities	823		4		5		822
Collateralized loan obligations	1,895		10		—		1,905
Other	5		—		—		5
Asset Liability Management securities	16,126		19		259		15,886
Other debt securities:
Direct bank purchase bonds	1,495		38		30		1,503
Other	163		1		—		164
Equity securities	10		—		—		10
Total securities available for sale	$	17,794	$	58	$	289	$	17,563

Securities in Unrealized Loss Position

The Company's securities held to maturity with a continuous unrealized loss position at December 31, 2018 and 2017 are shown below, separately for periods less than 12 months and 12 months or more.

	December 31, 2018
	Less than 12 months						12 months or more						Total
			Unrealized Losses						Unrealized Losses						Unrealized Losses
(Dollars in millions)	Fair Value		Recognized in OCI		Not Recognized in OCI		Fair Value		Recognized in OCI		Not Recognized in OCI		Fair Value		Recognized in OCI		Not Recognized in OCI
U.S. Treasury	$	—	$	—	$	—	$	496	$	—	$	2	$	496	$	—	$	2
U.S. government agency and government-sponsored agencies—residential mortgage backed securities	668		—		11		7,191		96		180		7,859		96		191
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities	29		—		—		1,396		42		18		1,425		42		18
Total securities held to maturity	$	697	$	—	$	11	$	9,083	$	138	$	200	$	9,780	$	138	$	211

	December 31, 2017
	Less than 12 months						12 months or more						Total
			Unrealized Losses						Unrealized Losses						Unrealized Losses
(Dollars in millions)	Fair Value		Recognized in OCI		Not Recognized in OCI		Fair Value		Recognized in OCI		Not Recognized in OCI		Fair Value		Recognized in OCI		Not Recognized in OCI
U.S. Treasury	$	494	$	—	$	1	$	—	$	—	$	—	$	494	$	—	$	1
U.S. government agency and government-sponsored agencies - residential mortgage-backed securities	2,649		—		31		$	4,000	31		99		6,649		31		130
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities	19		—		—		1,496		52		9		1,515		52		9
Total securities held to maturity	$	3,162	$	—	$	32	$	5,496	$	83	$	108	$	8,658	$	83	$	140

The Company's securities available for sale with a continuous unrealized loss position at December 31, 2018 and 2017 are shown below, identified for periods less than 12 months and 12 months or more.

	December 31, 2018
	Less than 12 months				12 months or more				Total
(Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Asset Liability Management securities:
U.S. Treasury	$	147	$	1	$	3,182	$	143	$	3,329	$	144
Residential mortgage-backed securities:
U.S. government agency and government-sponsored agencies	1,941		8		4,797		160		6,738		168
Privately issued	398		7		383		16		781		23
Privately issued - commercial mortgage-backed securities	364		6		512		14		876		20
Collateralized loan obligations	1,428		18		—		—		1,428		18
Asset Liability Management securities	4,278		40		8,874		333		13,152		373
Other debt securities:
Direct bank purchase bonds	221		6		417		24		638		30
Other	178		4		4		—		182		4
Total securities available for sale	$	4,677	$	50	$	9,295	$	357	$	13,972	$	407

	December 31, 2017
	Less than 12 months				12 months or more				Total
(Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Asset Liability Management securities:
U.S. Treasury	$	1,074	$	14	$	2,128	$	104	$	3,202	$	118
Residential mortgage-backed securities:
U.S. government agency and government-sponsored agencies	3,606		22		4,651		110		8,257		132
Privately issued	275		1		164		3		439		4
Privately issued - commercial mortgage-backed securities	447		3		80		2		527		5
Collateralized loan obligations	12		—		—		—		12		—
Asset Liability Management securities	5,414		40		7,023		219		12,437		259
Other debt securities:
Direct bank purchase bonds	58		4		563		26		621		30
Other	79		—		—		—		79		—
Equity securities	10		—		—		—		10		—
Total securities available for sale	$	5,561	$	44	$	7,586	$	245	$	13,147	$	289

Debt Securities by Contractual Maturity

The fair value of debt securities available for sale by contractual maturity are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties.

	December 31, 2018
(Dollars in millions)	One Year or Less		Over One Year Through Five Years		Over Five Years Through Ten Years		Over Ten Years		Total Fair Value
Asset Liability Management securities:
U.S. Treasury	$	—	$	1,284	$	2,145	$	—	$	3,429
Residential mortgage-backed securities:
U.S. government agency and government-sponsored agencies	—		212		1,306		6,489		8,007
Privately issued	—		—		—		864		864
Privately issued - commercial mortgage-backed securities	—		25		43		1,094		1,162
Collateralized loan obligations	—		1		352		1,121		1,474
Other	1		3		—		—		4
Asset Liability Management securities	1		1,525		3,846		9,568		14,940
Other debt securities:
Direct bank purchase bonds	26		424		612		128		1,190
Other	3		163		—		18		184
Total debt securities available for sale	$	30	$	2,112	$	4,458	$	9,714	$	16,314

The carrying amount and fair value of securities held to maturity by contractual maturity are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties.

	December 31, 2018
	Within One Year				Over One Year Through Five Years				Over Five Years Through Ten Years				Over Ten Years				Total
(Dollars in millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
U.S. Treasury	$	519	$	518	$	9	$	9	$	—	$	—	$	—	$	—	$	528	$	527
U.S. government-sponsored agencies	—		—		—		—		722		723		—		—		722		723
U.S. government agency and government-sponsored agencies - residential mortgage-backed securities	—		—		—		—		1,008		986		7,199		7,041		8,207		8,027
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities	46		46		787		797		—		—		611		600		1,444		1,443
Total securities held to maturity	$	565	$	564	$	796	$	806	$	1,730	$	1,709	$	7,810	$	7,641	$	10,901	$	10,720

Proceeds from Sales of Securities Available for Sale and Gross Realized Gains and Losses

The gross realized gains and losses from sales of available for sale securities for the years ended December 31, 2018, 2017 and 2016 are shown below. The specific identification method is used to calculate realized gains and losses on sales.

	For the Year Ended December 31,
(Dollars in millions)	2018		2017		2016
Gross realized gains	$	8	$	17	$	69
Gross realized losses	—		—		—

Schedule of Held to Maturity Securities Recognized and Not Recognized in Other Comprehensive Income (OCI) and Fair Values

At December 31, 2018 and 2017, the amortized cost, gross unrealized gains and losses recognized in OCI, carrying amount, gross unrealized gains and losses not recognized in OCI, and fair values of securities held to maturity are presented below. Management has asserted the positive intent and ability to hold these securities to maturity.

	December 31, 2018
			Recognized in OCI						Not Recognized in OCI
(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury	$	528	$	—	$	—	$	528	$	1	$	2	$	527
U.S. government-sponsored agencies	722		—		—		722		1		—		723
U.S. government agency and government-sponsored agencies - residential mortgage-backed securities	8,302		1		96		8,207		11		191		8,027
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities	1,486		—		42		1,444		17		18		1,443
Total securities held to maturity	$	11,038	$	1	$	138	$	10,901	$	30	$	211	$	10,720

	December 31, 2017
			Recognized in OCI						Not Recognized in OCI
(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury	$	525	$	—	$	—	$	525	$	3	$	1	$	527
U.S. government agency and government-sponsored agencies - residential mortgage-backed securities	7,870		2		31		7,841		15		130		7,726
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities	1,571		—		52		1,519		36		9		1,546
Total securities held to maturity	$	9,966	$	2	$	83	$	9,885	$	54	$	140	$	9,799