- (Tables)

12 Months Ended

Dec. 31, 2019

Investments [Abstract]

Summary of Investment Securities [Table Text Block]

	December 31, 2019
(In millions)	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Held-to-maturity
Municipal securities	$	592	$	5	$	—	$	597
Available-for-sale
U.S. Treasury securities	25		—		—		25
U.S. Government agencies and corporations:
Agency securities	1,301		5		4		1,302
Agency guaranteed mortgage-backed securities	9,518		83		42		9,559
Small Business Administration loan-backed securities	1,535		1		41		1,495
Municipal securities	1,282		37		—		1,319
Other debt securities	25		—		—		25
Total available-for-sale	13,686		126		87		13,725
Total investment securities	$	14,278	$	131	$	87	$	14,322

	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	15,040		23		326		14,737
Total investment securities	$	15,814	$	27	$	337	$	15,504

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	$	101	$	102	$	122	$	122
Due after one year through five years	215		216		718		726
Due after five years through ten years	156		159		2,434		2,450
Due after ten years	120		120		10,412		10,427
Total	$	592	$	597	$	13,686	$	13,725

Gain (Loss) on Securities [Table Text Block]

	2019				2018				2017
(In millions)	Gross gains		Gross losses		Gross gains		Gross losses		Gross gains		Gross losses
Other noninterest-bearing investments	$	20	$	17	$	17	$	16	$	22	$	8
Net gains			$	3			$	1			$	14

Schedule of Unrealized Loss on Investments [Table Text Block]

	December 31, 2019
	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	$	—	$	73	$	—	$	45	$	—	$	118
Available-for-sale
U.S. Government agencies and corporations:
Agency securities	2		222		2		359		4		581
Agency guaranteed mortgage-backed securities	4		1,173		38		3,215		42		4,388
Small Business Administration loan-backed securities	1		172		40		1,215		41		1,387
Municipal securities	—		50		—		5		—		55
Other	—		—		—		—		—		—
Total available-for-sale	7		1,617		80		4,794		87		6,411
Total	$	7	$	1,690	$	80	$	4,839	$	87	$	6,529

	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

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

(In millions)	2019						2018						2017
	Taxable		Nontaxable		Total		Taxable		Nontaxable		Total		Taxable		Nontaxable		Total
Investment securities:
Held-to-maturity	$	9	$	13	$	22	$	10	$	14	$	24	$	10	$	13	$	23
Available-for-sale	308		25		333		295		26		321		277		24		301
Trading	1		6		7		1		4		5		—		2		2
Total	$	318	$	44	$	362	$	306	$	44	$	350	$	287	$	39	$	326