Fair Value (Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis Using Level 3 Inputs) (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Private equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of assets, Beginning balance	$ 83	$ 79	$ 80	$ 107
Unrealized securities gains (losses), net	68	(4)	69	(24)
Other noninterest income (expense)	0	0		0
Purchases	2	2	6	3
Cost of investments sold	(4)	0	(6)	(9)
Redemptions and paydowns		0		0
Transfers out	(77)	0	(77)	0
Fair value of assets, Ending balance	72	77	72	77
Ag loan svcg and int-only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of assets, Beginning balance	15	17	16	18
Unrealized securities gains (losses), net	0	0	0	0
Other noninterest income (expense)	0	0	(1)	(1)
Purchases	0	0	0	0
Cost of investments sold	0	0	0	0
Redemptions and paydowns		0	0	0
Transfers out	0	0	0	0
Fair value of assets, Ending balance	$ 15	$ 17	$ 15	$ 17