MSR (Activity Related to the MSR Portfolio) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Servicing Assets at Fair Value
Changes in fair value and settlement of free-standing derivatives purchased to economically hedge the MSR portfolio (Mortgage banking net revenue)	$ 24	$ 90	$ 95
Recovery of (provision for) MSR impairment (Mortgage banking net revenue)	$ 7	$ 4	$ (65)