Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	9 Months Ended
	May 31, 2012	Sep. 30, 2012 item	Sep. 30, 2011	Dec. 31, 2011
Stockholders' Equity
Common stock, authorized shares		100,000,000
Voting rights per common share		1
Common stock, outstanding shares		15,795,521		15,593,506
Authorized amount of repurchase under stock purchase plan	$ 10
Common Stock purchased under stock purchase plan		47,000
Aggregate cost of Common Stock purchased under stock purchase plan		1.2
Shares acquired by the entity		214,000	25,000
Cost of shares acquired by the entity		$ 5.1	$ 0.5