Mortgage Banking Activity - Residential Mortgage Loans (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Balance at beginning of period	$ 590
Balance at end of period	650	$ 590
Mortgage loans
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Balance at beginning of period	44	250
Originations and purchases	120	1,275
Sales, net of gains	(103)	(1,481)
Mortgage loans transferred from (to) held for investment	0	0
Balance at end of period	$ 61	$ 44