Derivative and Hedging Activities - Notional Amount and Fair Value of Derivative Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Assets
Net gain on loan sales and securitizations	$ 6	$ 18	$ 19	$ 38
Derivatives designated as hedging instruments: | Interest rate swaps | Other Assets | Fair Value Hedging
Assets
Notional Amount	2,993		2,993		$ 0
Fair Value	0		0		0
Derivatives designated as hedging instruments: | Interest rate swaps | Other Assets | Cash Flow Hedging
Assets
Notional Amount	2,000		2,000		0
Fair Value	0		0		0
Derivatives designated as hedging instruments: | Interest rate swaps | Other Liabilities | Fair Value Hedging
Assets
Fair Value	0		0		0
Derivatives designated as hedging instruments: | Interest rate swaps | Other Liabilities | Cash Flow Hedging
Assets
Fair Value	0		0		0
Derivatives not designated as hedging instruments: | Interest rate swaps | Other Assets
Assets
Notional Amount	3,229		3,229		3,323
Fair Value	17		17		15
Derivatives not designated as hedging instruments: | Interest rate swaps | Other Liabilities
Assets
Fair Value	22		22		30
Derivatives not designated as hedging instruments: | Rate lock commitments | Other Assets
Assets
Notional Amount	439		439		563
Fair Value	4		4		3
Derivatives not designated as hedging instruments: | Rate lock commitments | Other Liabilities
Assets
Fair Value	3		3		3
Derivatives not designated as hedging instruments: | Mortgage-backed securities forwards
Assets
Net gain on loan sales and securitizations	0	$ 0	(9)	$ 23
Derivatives not designated as hedging instruments: | Mortgage-backed securities forwards | Other Assets
Assets
Notional Amount	269		269		344
Fair Value	0		0		7
Derivatives not designated as hedging instruments: | Mortgage-backed securities forwards | Other Liabilities
Assets
Fair Value	$ 5		$ 5		$ 2