Investment Securities - Schedule of Amortized Cost, Unrealized Gains/(Losses) and Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 10,092
Securities available for sale at fair value	8,718	$ 8,707
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,385	712
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(163)	(7)
Fair Value	1,222	705
Government agency issued MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,457	5,062
Gross Unrealized Gains	0	42
Gross Unrealized Losses	(767)	(49)
Securities available for sale at fair value	4,690	5,055
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	908	509
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(116)	(5)
Fair Value	792	504
Government agency issued CMO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,775	2,296
Gross Unrealized Gains	0	8
Gross Unrealized Losses	(360)	(47)
Securities available for sale at fair value	2,415	2,257
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	477	203
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(47)	(2)
Fair Value	430	201
Other U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,212	861
Gross Unrealized Gains	0	4
Gross Unrealized Losses	(156)	(15)
Securities available for sale at fair value	1,056	850
States and municipalities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	648	535
Gross Unrealized Gains	0	11
Gross Unrealized Losses	(91)	(1)
Securities available for sale at fair value	557	545
Securities available-for-sale, excluding interest only strip
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,092	8,754
Gross Unrealized Gains	0	65
Gross Unrealized Losses	(1,374)	(112)
Securities available for sale at fair value	8,718	8,707
Securities available-for-sale, excluding interest only strip \| Collateral Pledged
Debt Securities, Available-for-sale [Line Items]
Securities available for sale at fair value	$ 6,400	$ 6,500

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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Amount, before tax, of unrealized loss 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 excluding accrued interest, before allowance for credit loss, 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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Amount excluding accrued interest, 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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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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