Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	$ 380	$ 313	$ 380	$ 313
Total Losses	(29)	(17)	(109)	(56)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	9	0	9
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	380	304	380	304
Commercial loans held for sale | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	7		7
Total Losses	0		0
Commercial loans held for sale | Commercial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0		0
Commercial loans held for sale | Commercial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0		0
Commercial loans held for sale | Commercial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	7		7
Commercial loans and leases | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	171	180	171	180
Total Losses	(21)	(15)	(97)	(47)
Commercial loans and leases | Commercial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Commercial loans and leases | Commercial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Commercial loans and leases | Commercial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	171	180	171	180
Consumer and residential mortgage loans | Consumer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	193	115	193	115
Total Losses	(6)	0	(8)	0
Consumer and residential mortgage loans | Consumer | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Consumer and residential mortgage loans | Consumer | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Consumer and residential mortgage loans | Consumer | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	193	115	193	115
OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	5	2	5	2
Total Losses	(1)	0	(1)	1
OREO | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
OREO | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
OREO | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	5	2	5	2
Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	4	2	4	2
Total Losses	0	(1)	(1)	(1)
Bank premises and equipment | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Bank premises and equipment | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Bank premises and equipment | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	4	2	4	2
Operating lease equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value		5		5
Total Losses		0		(2)
Operating lease equipment | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value		0		0
Operating lease equipment | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value		0		0
Operating lease equipment | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value		5		5
Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	9	0	9
Total Losses	(1)	(1)	(2)	(7)
Private equity investments | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0	0	0
Private equity investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	9	0	9
Private equity investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	$ 0	$ 0	$ 0	$ 0