MSR (Fair Value of the Servicing Rights) (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fixed Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	$ 757	$ 823
Fair value at end of period	722	757
Adjustable Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	27	33
Fair value at end of period	22	27
Fixed Rate Automobile Loans
Servicing Assets at Fair Value
Fair value at beginning of period	1	2
Fair value at end of period	$ 0	$ 1