Stockholders' Equity (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 29, 2016	Mar. 31, 2016	Mar. 31, 2015	May. 06, 2015
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired		2,083,000	334,000
Treasury Stock, Value, Acquired, Cost Method		$ 296,515	$ 60,026
Subsequent Event [Member]
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired	245,000
Treasury Stock, Value, Acquired, Cost Method	$ 34,136
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 1,000,000
Common Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Total remaining amount for repurchases under program	$ 425,213