Fair Value Measurement and Fair Value of Financial Instruments (Details 4) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Loans:
Impaired loans	$ 549		$ 549		$ 503
Loss Impaired loans	1	$ 2	(13)	$ (33)
Impairment of Premises and Equipment	1		1
Other assets:
Loss on OREO	(1)	(2)	(2)	(5)
Loss on Private equity investments			(5)
Impairment of Intangible Assets, Finite-lived	(3)		(3)
Loss, Total	(4)	0	(24)	(38)
Fair Value Measurements, Nonrecurring
Loans:
Impaired loans	18	89	18	89
Property, Plant, and Equipment, Fair Value Disclosure	2		2
Other assets:
OREO	6	13	6	13
Private Equity Investments	7		7
Total	36	102	36	102
Finite-lived Intangible Assets, Fair Value Disclosure	3		3
Fair Value Measurements, Nonrecurring | Level 3
Loans:
Impaired loans	18	89	18	89
Property, Plant, and Equipment, Fair Value Disclosure	2		2
Other assets:
OREO	6	13	6	13
Private Equity Investments	7		7
Total	36	$ 102	36	$ 102
Finite-lived Intangible Assets, Fair Value Disclosure	$ 3		$ 3