Treasury Stock (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 10, 2016
Equity [Abstract]
Shares available for repurchase (in shares)	300,000
Shares repurchased (in shares)	1,817,000	384,000	153,000
Cost of shares repurchased	$ 89,395	$ 16,168	$ 3,607
Treasury stock reissued (in shares)		15,000	30,000
Subsequent event
Class of stock [Line Items]
Stock repurchase program, additional number of shares authorized				100,000
Stock repurchase program, number of shares authorized to be repurchased				400,000