Fair Value Measurement and Fair Value of Financial Instruments - Assets Measured on Nonrecurring Basis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Loans:
Impaired loans	$ 786	$ 833
Impaired loans, gain (loss)	(249)	(95)
Premises and equipment		(6)
Other assets:
Loans held for sale	0	0
Loans held for sale, gain (loss)	0	3
OREO	3	21
OREO, gain (loss)	(1)	(2)
Private equity investments, gain (loss)	(12)	(5)
Software	0
Software, gain (loss)	(5)
Intangible Assets, gain (loss)	(1)	(4)
Consolidated LIHC VIE	0
Consolidated LIHC VIE, gain (loss)	(35)
Total, gain (loss)	(303)	(115)
Level 2
Loans:
Impaired loans	0	0
Other assets:
OREO	0	0
Private equity investments	0	0
Intangible assets	0	0
Total	0	0
Level 1
Loans:
Impaired loans	0	0
Other assets:
OREO	0	0
Private equity investments	0	0
Intangible assets	0	0
Total	0	0
Fair Value Measurements, Nonrecurring
Loans:
Impaired loans	181	154
Other assets:
Loans held for sale	25	18
OREO	1	6
Private equity investments	10	7
Software	13
Intangible assets	0	2
Consolidated LIHC VIE	112
Total	342	187
Fair Value Measurements, Nonrecurring | Level 3
Loans:
Impaired loans	181	154
Other assets:
Loans held for sale	25	18
OREO	1	6
Private equity investments	10	7
Software	13
Intangible assets	0	2
Consolidated LIHC VIE	112
Total	$ 342	$ 187