Variable Interest Entities - Assets and Liabilities of Consolidated VIEs (Details) $ in Millions	Dec. 31, 2017 USD ($) investment	Dec. 31, 2016 USD ($)
Consolidated Assets
Interest Bearing Deposits in Banks	$ 1,335	$ 3,844
Loans Held for Investment, net	79,538	76,912
Other assets	8,800	8,496
Total Assets	0	0
Consolidated Liabilities
Other liabilities	2,143	2,520
Consolidated VIEs
Consolidated Assets
Interest Bearing Deposits in Banks	1	0
Loans Held for Investment, net	583	641
Other assets	226	286
Total Assets	810	927
Consolidated Liabilities
Other liabilities	24	54
Total Liabilities	24	54
Consolidated VIEs | LIHC investments
Consolidated Assets
Interest Bearing Deposits in Banks	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Other assets	68	112
Total Assets	68	112
Consolidated Liabilities
Other liabilities	0	0
Total Liabilities	$ 0	0
Number of LIHC investment fund | investment	2
Consolidated VIEs | Leasing investments
Consolidated Assets
Interest Bearing Deposits in Banks	$ 1	0
Loans and Leases Receivable, Net of Deferred Income	583	641
Other assets	158	174
Total Assets	742	815
Consolidated Liabilities
Other liabilities	24	54
Total Liabilities	$ 24	$ 54