Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Dec. 01, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Increase in share repurchase authorized amount	$ 300,000
Purchase of common stock (in shares)		266,000	738,593	2,811,002
Purchase and accruals of common stock		$ 29,100	$ 55,000
Purchase of common stock		29,074	$ 57,272	$ 210,822
Remaining authorized repurchase amount		$ 551,000
Common stock, shares authorized (in shares)		150,000,000	150,000,000
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)		5,000,000	5,000,000
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, shares issued (in shares)		0	0