Stock Repurchases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Aug. 19, 2015
Stock Repurchases [Abstract]
Stock Repurchase Program, Authorized Repurchase Amount				$ 100,000,000
Stock Repurchased During Period, Shares	1,479,454	2,924,306	2,146,488
Payments for Repurchase of Common Stock	$ 59,784,000	$ 81,653,000	$ 31,854,000
Stock Repurchased During Period, Value	65,300,000	$ 82,500,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 23,200,000