Fair Value of the Servicing Rights (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fixed Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	$ 757	$ 759	$ 823
Fair value at end of period	660	757	759
Adjustable Rate Residential Mortgage Loans
Servicing Assets at Fair Value
Fair value at beginning of period	27	29	33
Fair value at end of period	25	27	29
Fixed Rate Automobile Loans
Servicing Assets at Fair Value
Fair value at beginning of period	$ 1	1	2
Fair value at end of period		$ 1	$ 1