Income Taxes (Applicable Income Taxes Included in the Consolidated Statements of Income) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation Of Provision Of Income Taxes
U.S. Federal income taxes	$ 598	$ 662	$ 424
State and local income taxes	55	55	34
Foreign income taxes	0	13	8
Total current tax expense (benefit)	653	730	466
U.S. Federal income taxes	(133)	(78)	71
State and local income taxes	(14)	6	9
Foreign income taxes	(1)	1	(1)
Total deferred tax expense (benefit)	(148)	(71)	79
Applicable income tax expense	$ 505	$ 659	$ 545