Derivative Financial Instruments - Notional Amount, Estimated Fair Value and Maturity of Derivative Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Derivatives designated as hedging instruments
Liabilities
Fair value		$ 0
Assets
Fair value	$ 2	0
Derivatives designated as hedging instruments | Assets
Assets
Notional amount		85
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on commercial loans
Assets
Fair value	2
Derivatives designated as hedging instruments | Interest rate swaps on commercial loans | Assets
Assets
Notional amount		2,000
Fair value		2
Derivatives designated as hedging instruments | Interest rate swaps on custodial deposits
Liabilities
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on custodial deposits | Liabilities
Liabilities
Notional amount		800
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on AFS securities
Liabilities
Fair value		0
Assets
Fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps on AFS securities | Assets
Assets
Notional amount		85
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on AFS securities | Liabilities
Liabilities
Notional amount		350
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on subordinated debt
Assets
Fair value	0
Derivatives designated as hedging instruments | Interest rate swaps on HFI residential first mortgages
Liabilities
Fair value		0
Derivatives designated as hedging instruments | Interest rate swaps on HFI residential first mortgages | Liabilities
Liabilities
Notional amount		100
Fair value		0
Derivatives designated as hedging instruments | Fair Value Hedging | Assets
Assets
Notional amount	250
Fair value	0
Derivatives designated as hedging instruments | Fair Value Hedging | Liabilities
Liabilities
Notional amount		450
Fair value		0
Derivatives designated as hedging instruments | Fair Value Hedging | Interest rate swaps on AFS securities | Assets
Assets
Notional amount	100
Fair value	0
Derivatives designated as hedging instruments | Fair Value Hedging | Interest rate swaps on subordinated debt | Assets
Assets
Notional amount	150
Fair value	0
Derivatives not designated as hedging instruments
Liabilities
Fair value	67	20
Assets
Fair value	305	87
Derivatives not designated as hedging instruments | Assets
Assets
Notional amount	21,060	14,364
Fair value	330	141
Derivatives not designated as hedging instruments | Liabilities
Liabilities
Notional amount	8,512	5,886
Fair value	94	20
Derivatives not designated as hedging instruments | Futures | Assets
Assets
Notional amount	1,053	1,117
Fair value	2	0
Derivatives not designated as hedging instruments | Mortgage-backed securities forwards
Liabilities
Fair value	45	14
Assets
Fair value	200	10
Derivatives not designated as hedging instruments | Mortgage-backed securities forwards | Assets
Assets
Notional amount	11,684	4,008
Fair value	200	11
Derivatives not designated as hedging instruments | Mortgage-backed securities forwards | Liabilities
Liabilities
Notional amount	4,629	4,023
Fair value	45	14
Derivatives not designated as hedging instruments | Rate lock commitments | Assets
Assets
Notional amount	3,259	5,169
Fair value	23	54
Derivatives not designated as hedging instruments | Rate lock commitments | Liabilities
Liabilities
Notional amount	2,112	370
Fair value	27	1
Derivatives not designated as hedging instruments | Interest rate swaps and swaptions
Assets
Fair value	105
Derivatives not designated as hedging instruments | Interest rate swaps and swaptions | Assets
Assets
Notional amount	5,064	4,070
Fair value	105	76
Derivatives not designated as hedging instruments | Interest rate swaps and swaptions | Liabilities
Liabilities
Notional amount		1,493
Fair value		5
Derivatives not designated as hedging instruments | Interest rate swaps
Liabilities
Fair value	22	$ 6
Derivatives not designated as hedging instruments | Interest rate swaps | Liabilities
Liabilities
Notional amount	1,771
Fair value	$ 22