Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2016	Jan. 21, 2015
Share repurchase program
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				20,000,000.0
UpfrontPaymentUnderAcceleratedStockRepurchaseProgram		$ 100,000
Stock Repurchased and Retired During Period, Shares	700,000	7,812,000	700,000
Stock Repurchased and Retired During Period, Value		$ 80,000
UnsettledForwardContractIndexedtoIssuersStockClassifiedwithinStock		$ 20,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	11,500,000		11,500,000