Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	$ 7,599
Marketable securities amortized cost	8,392	$ 9,933
Marketable securities gross unrealized gain	18	14
Marketable securities gross unrealized loss	797	873
Debt securities, available-for-sale	7,599	9,060
Equity investments with readily determinable fair values, at fair value	14	14
Total securities	7,613	9,074
Interest receivable	30	31
Agency - commercial
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	5,133	5,242
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	11	7
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(428)	(460)
Debt securities, available-for-sale	4,716	4,789
Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	3,243	4,675
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	7	7
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(367)	(411)
Debt securities, available-for-sale	2,883	4,271
Mortgage Backed Securities And Other Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	8,376	9,917
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	18	14
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(795)	(871)
Debt securities, available-for-sale	7,599	9,060
Equity Securities
Debt Securities, Available-for-Sale [Abstract]
Equity securities, FV-NI, cost	16	16
Equity securities, FV-NI, unrealized loss	2	2
Equity investments with readily determinable fair values, at fair value	14	14
GSE certificates \| Agency - commercial
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	1,388	1,457
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(143)	(160)
Debt securities, available-for-sale	1,246	1,297
GSE CMOs \| Agency - commercial
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	3,562	3,600
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	4	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(284)	(300)
Debt securities, available-for-sale	3,282	3,301
Private Label CMOs \| Agency - commercial
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	183	185
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	6	6
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(1)	0
Debt securities, available-for-sale	188	191
U. S. Treasury obligations \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	0	1,491
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(4)
Debt securities, available-for-sale	0	1,487
GSE debentures \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	1,899	1,749
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(310)	(351)
Debt securities, available-for-sale	1,589	1,398
Asset-backed securities \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	345	375
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(10)	(14)
Debt securities, available-for-sale	335	361
Municipal bonds \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	18	30
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale	18	30
Corporate bonds \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	864	913
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	2	2
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(33)	(30)
Debt securities, available-for-sale	833	885
Foreign notes \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	20	20
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(1)	0
Debt securities, available-for-sale	19	20
Capital trust notes \| Debt Securities
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, amortized cost, total	97	97
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	5	5
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(13)	(12)
Debt securities, available-for-sale	89	90
Mutual funds and common stock \| Equity Securities
Debt Securities, Available-for-Sale [Abstract]
Equity securities, FV-NI, cost	16	16
Equity securities, FV-NI, unrealized loss	2	2
Equity investments with readily determinable fair values, at fair value	$ 14	$ 14

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Marketable Securities Gross Unrealized Gain

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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