Commitments, Contingencies and Guarantees (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Commitments to extend credit
Commitment, Contingencies and Guarantees disclosures
Commitments	$ 35,864
Issued standby and commercial letters of credit
Commitment, Contingencies and Guarantees disclosures
Commitments	$ 5,796
Maximum term	1 year
Carrying value	$ 4
Other commitments
Commitment, Contingencies and Guarantees disclosures
Commitments	115
Oil and Gas [Member] | Commitments to extend credit
Commitment, Contingencies and Guarantees disclosures
Commitments	$ 3,296	$ 6,832