MSR (Changes in the Servicing Rights) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Servicing Assets at Fair Value
Carrying amount before valuation allowance as of the beginning of the period	$ 1,204	$ 1,392
Servicing rights that result from the transfer of residential mortgage loans	83	63
Amortization	(131)	(140)	$ (121)
Other-than-temporary impairment	0	(111)
Carrying amount before valuation allowance	1,156	1,204	1,392
Valuation allowance for servicing rights:
Beginning balance	(419)	(534)
(Provision for) recovery of MSR impairment	7	4
Other-than-temporary impairment	0	111
Ending balance	(412)	(419)	$ (534)
Carrying amount as of the end of the period	$ 744	$ 785