Summarized StoneRiver Financial Information (Detail) (StoneRiver Group, L.P., USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
StoneRiver Group, L.P.
Schedule of Equity Method Investments [Line Items]
Total revenue	$ 732	$ 806	$ 826
Operating income	24	47	42
Income from continuing operations	243	18	16
Net income	243	16	23
Current assets	74	175
Noncurrent assets	629	576
Current liabilities	97	195
Noncurrent liabilities	527	421
Noncontrolling interest		$ 17