MSR (Fair Value of the Servicing Rights) (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Fixed Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	$ 757	$ 731	$ 823
Fair value at end of period	597	757	731
Adjustable Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	27	25	33
Fair value at end of period	22	27	25
Fixed Rate Automobile Loans
Servicing Assets at Fair Value
Fair value at beginning of period	1	1	2
Fair value at end of period	$ 0	$ 1	$ 1