Income Taxes - Additional Information (Details) (USD $)	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013 Group Eight [Member]	Jul. 31, 2013 Senior Notes Sold In 2013 [Member]	Mar. 31, 2013 UNITED KINGDOM Valuation Allowance [Member]
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 34,000,000	$ 27,000,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%
Income Tax Reconciliation, Repatriation of Foreign Earnings	1,000,000	2,000,000
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	4,000,000
Income Tax Expense Reduction					2,000,000
Senior notes issued				750,000,000
Deferred Tax Assets, Valuation Allowance			$ 700,000,000