Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		1 Months Ended
	Mar. 31, 2015 item	Mar. 31, 2014	May 31, 2014	Dec. 31, 2014
Stockholders' equity
Cost of shares acquired by the entity	$ 0.1	$ 0.1
Authorized shares of common stock	100,000,000
Voting rights per common share	1
Common stock, outstanding shares	16,725,000			16,748,000
Shares acquired by the entity	1,000	3,000
2014 Stock Purchase Program
Stockholders' equity
Period over which repurchases allowed under the plan			12 months
Common stock purchased under the stock purchase plan (in shares)	58,100
Cost of shares of common stock acquired	3.3
2014 Stock Purchase Program | Maximum
Stockholders' equity
Authorized amount of repurchase under the stock purchase plan			25
2013 Stock Purchase Program
Stockholders' equity
Authorized amount of repurchase under the stock purchase plan			10
Preceding period in which repurchases were allowed under the plan			12 months
Common stock purchased under the stock purchase plan (in shares)		0