Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jul. 30, 2014
Equity [Abstract]
Dividends declared per common share	$ 0.06	$ 0.05	$ 0.05	$ 0.11	$ 0.10
Stock Repurchase Program, Authorized Amount						$ 1,400,000,000
Repurchases of common stock				$ 126,000,000	$ 113,000,000
Shares repurchased during period				5,822,021
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 185,000,000			$ 185,000,000