Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Restricted Cash and Cash Equivalents	$ 1,790,000,000	$ 991,000,000
Mortgages Held-for-sale, Fair Value Disclosure	12,330,000,000	15,035,000,000
Allowance on accrued interest receivable	107,000,000	0
Allowance for loan losses	6,773,000,000	4,234,000,000
Other Assets, Fair Value Disclosure	5,591,000,000	4,627,000,000
Debt instrument recorded at fair value	2,798,000,000	3,938,000,000
Senior preferred stock, at redemption value	$ 84,090,000,000	$ 79,322,000,000
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	4,000,000,000	4,000,000,000
Common Stock, Shares, Issued	725,863,886	725,863,886
Common Stock, Shares, Outstanding	650,059,292	650,059,033
Treasury Stock, Shares	75,804,594	75,804,853