MSR (Fair Value of the Servicing Rights) (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Servicing Assets at Fair Value
Fair value at beginning of period	$ 744
Fair value at end of period	849	$ 744
Fixed Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	722	598	$ 757
Fair value at end of period	830	722	598
Adjustable Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	22	23	27
Fair value at end of period	19	22	23
Fixed Rate Automobile Loans
Servicing Assets at Fair Value
Fair value at beginning of period	0	0	1
Fair value at end of period	$ 0	$ 0	$ 0