Applicable Income Taxes Included in the Consolidated Statements of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Provision Of Income Taxes [Abstract]
U.S. Federal income taxes	$ 662	$ 424	$ 494
State and local income taxes	55	34	23
Foreign income taxes	13	8	2
Total current tax (benefit) expense	730	466	519
U.S. Federal income taxes	(78)	71	232
State and local income taxes	6	9	23
Foreign income taxes	1	(1)	(2)
Total deferred tax expense (benefit)	(71)	79	253
Applicable income tax expense	$ 659	$ 545	$ 772