Subsequent Event (Details) (USD $)	12 Months Ended			2 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 09, 2015	Jan. 06, 2015
Subsequent Event [Line Items]
Purchase of treasury shares	$ 0	$ 3,884,000	$ 3,257,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock repurchase program, remaining authorized repurchase amount				4,800,000
Subsequent Event [Member] | December 2014 Share Repurchase Agreement [Member]
Subsequent Event [Line Items]
Purchase of treasury shares, shares				307,715	179,168
Purchase of treasury shares				$ 3,200,000	$ 1,800,000