Investment Securities - (Tables)

12 Months Ended

Dec. 31, 2018

Investments [Abstract]

Summary of Investment Securities [Table Text Block]

	December 31, 2018
(In millions)	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Held-to-maturity
Municipal securities	$	774	$	4	$	11	$	767
Available-for-sale
U.S. Treasury securities	40		—		—		40
U.S. Government agencies and corporations:
Agency securities	1,394		—		19		1,375
Agency guaranteed mortgage-backed securities	10,236		18		240		10,014
Small Business Administration loan-backed securities	2,042		1		47		1,996
Municipal securities	1,303		4		16		1,291
Other debt securities	25		—		4		21
Total available-for-sale debt securities	15,040		23		326		14,737
Money market mutual funds and other	—		—		—		—
Total available-for-sale	15,040		23		326		14,737
Total investment securities	$	15,814	$	27	$	337	$	15,504

	December 31, 2017
(In millions)	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Held-to-maturity
Municipal securities	$	770	$	5	$	13	$	762
Available-for-sale
U.S. Treasury securities	25		—		—		25
U.S. Government agencies and corporations:
Agency securities	1,830		1		13		1,818
Agency guaranteed mortgage-backed securities	9,798		9		141		9,666
Small Business Administration loan-backed securities	2,227		10		15		2,222
Municipal securities	1,336		9		11		1,334
Other debt securities	25		—		1		24
Total available-for-sale debt securities	15,241		29		181		15,089
Money market mutual funds and other	72		—		—		72
Total available-for-sale	15,313		29		181		15,161
Total investment securities	$	16,083	$	34	$	194	$	15,923

Investments Classified by Contractual Maturity Date [Table Text Block]

	Held-to-maturity				Available-for-sale
(In millions)	Amortized cost		Estimated fair value		Amortized cost		Estimated fair value
Due in one year or less	$	242	$	242	$	1,955	$	1,916
Due after one year through five years	344		341		5,806		5,690
Due after five years through ten years	135		133		4,608		4,520
Due after ten years	53		51		2,671		2,611
Total	$	774	$	767	$	15,040	$	14,737

Gain (Loss) on Securities [Table Text Block]

	2018			2017			2016
(In millions)	Gross gains	Gross losses		Gross gains	Gross losses		Gross gains	Gross losses
Investment securities:
Other noninterest-bearing investments	17	16		22	8		21	14
Net gains		$	1		$	14		$	7

Schedule of Unrealized Loss on Investments [Table Text Block]

	December 31, 2018
	Less than 12 months				12 months or more				Total
(In millions)	Gross unrealized losses		Estimated fair value		Gross unrealized losses		Estimated fair value		Gross unrealized losses		Estimated fair value
Held-to-maturity
Municipal securities	$	1	$	86	$	10	$	438	$	11	$	524
Available-for-sale
U.S. Government agencies and corporations:
Agency securities	2		245		17		913		19		1,158
Agency guaranteed mortgage-backed securities	16		1,081		224		6,661		240		7,742
Small Business Administration loan-backed securities	19		1,180		28		711		47		1,891
Municipal securities	2		266		14		641		16		907
Other	—		—		4		11		4		11
Total available-for-sale	39		2,772		287		8,937		326		11,709
Total	$	40	$	2,858	$	297	$	9,375	$	337	$	12,233

	December 31, 2017
	Less than 12 months				12 months or more				Total
(In millions)	Gross unrealized losses		Estimated fair value		Gross unrealized losses		Estimated fair value		Gross unrealized losses		Estimated fair value
Held-to-maturity
Municipal securities	$	3	$	263	$	10	$	292	$	13	$	555
Available-for-sale
U.S. Government agencies and corporations:
Agency securities	6		808		7		808		13		1,616
Agency guaranteed mortgage-backed securities	29		3,609		112		4,721		141		8,330
Small Business Administration loan-backed securities	3		408		12		649		15		1,057
Municipal securities	6		554		5		230		11		784
Other	—		—		1		14		1		14
Total available-for-sale	44		5,379		137		6,422		181		11,801
Total	$	47	$	5,642	$	147	$	6,714	$	194	$	12,356

Tax and Nontaxable Interest Income by Investment Type [Table Text Block]

(In millions)	2018						2017						2016
	Taxable		Nontaxable		Total		Taxable		Nontaxable		Total		Taxable		Nontaxable		Total
Investment securities:
Held-to-maturity	$	10	$	14	$	24	$	10	$	13	$	23	$	10	$	13	$	23
Available-for-sale	295		26		321		277		24		301		166		12		178
Trading	5		—		5		2		—		2		3		—		3
Total	$	310	$	40	$	350	$	289	$	37	$	326	$	179	$	25	$	204