Stock Repurchase (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount		$ 250,000
Stock Repurchased During Period, Shares	2,213,100
Treasury Stock Acquired, Average Cost Per Share	$ 32.37