Treasury Stock (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jul. 28, 2015
Class of Stock [Line Items]
Shares repurchased (in shares)	648,708	349,533
Cost of shares repurchased	$ 34,297	$ 14,275
Treasury stock reissued (shares)		15,000
Shares available for repurchase (in shares)	526,069
Subsequent Event [Member]
Class of Stock [Line Items]
Stock repurchase program, additional number of shares authorized to be repurchased (in shares)			403,003
Stock repurchase program, number of shares authorized to be repurchased (in shares)			700,000