Commitments (Summary of Significant Commitments) (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Commitments to extend credit
Long-term Purchase Commitment
Commitments	$ 67,342	$ 66,884
Letters of credit
Long-term Purchase Commitment
Commitments	2,737	3,055
Forward contracts related to held for sale residential mortgage loans
Long-term Purchase Commitment
Commitments	1,713	1,330
Noncancelable operating lease obligations
Long-term Purchase Commitment
Commitments	599	635
Purchase obligations
Long-term Purchase Commitment
Commitments	65	60
Capital commitments for private equity investments
Long-term Purchase Commitment
Commitments	52	60
Capital expenditures
Long-term Purchase Commitment
Commitments	28	30
Capital lease obligations
Long-term Purchase Commitment
Commitments	$ 22	$ 27