Variable Interest Entities - Carrying Amounts related to Unconsolidated VIEs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entities
Fair value of liabilities assumed	$ 0	$ 0	$ 573
Unconsolidated Assets
Securities available for sale	14,344	13,724
Loans Held for Investment	77,599	76,804
Other Assets	5,377	4,630
Unconsolidated Liabilities
Other Liabilities	2,023	1,897
Interest bearing deposits in banks	2,749	3,930
Unconsolidated VIEs
Unconsolidated Assets
Securities available for sale	25	25
Loans Held for Investment	289	213
Other Assets	2,376	2,007
Total Assets	2,695	2,245
Unconsolidated Liabilities
Other Liabilities	485	488
Total Liabilities	485	488
Maximum Exposure to Loss	2,716	2,263
Interest bearing deposits in banks	5
Unconsolidated VIEs | LIHC investments
Variable Interest Entities
Fair value of liabilities assumed	177	226	$ 130
Unconsolidated Assets
Securities available for sale	25	25
Loans Held for Investment	220	163
Other Assets	1,166	1,101
Total Assets	1,411	1,289
Unconsolidated Liabilities
Other Liabilities	424	433
Total Liabilities	424	433
Maximum Exposure to Loss	1,411	1,289
Unconsolidated VIEs | Leasing investments
Unconsolidated Assets
Securities available for sale	0	0
Loans Held for Investment	20	21
Other Assets	1,200	886
Total Assets	1,225	907
Unconsolidated Liabilities
Other Liabilities	61	55
Total Liabilities	61	55
Maximum Exposure to Loss	1,245	923
Interest bearing deposits in banks	5
Unconsolidated VIEs | Other investments
Unconsolidated Assets
Securities available for sale	0	0
Loans Held for Investment	49	29
Other Assets	10	20
Total Assets	59	49
Unconsolidated Liabilities
Other Liabilities	0	0
Total Liabilities	0	0
Maximum Exposure to Loss	$ 60	$ 51