MSR (Changes in the Servicing Assets) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Servicing Assets at Fair Value
Carrying amount before valuation allowance as of the beginning of the period			$ 1,204,000,000	$ 1,392,000,000
Servicing rights that result from the transfer of residential mortgage loans			55,000,000	48,000,000
Amortization	$ (35,000,000)	$ (37,000,000)	(96,000,000)	(111,000,000)
Carrying amount before valuation allowance	1,163,000,000	1,329,000,000	1,163,000,000	1,329,000,000
Valuation allowance for servicing rights:
Beginning balance			(419,000,000)	(534,000,000)
(Provision for) recovery of MSR impairment			(125,000,000)	(38,000,000)
Ending balance	(544,000,000)	(572,000,000)	(544,000,000)	(572,000,000)
Carrying amount as of the end of the period	$ 619,000,000	$ 757,000,000	$ 619,000,000	$ 757,000,000	$ 785,000,000