Stockholders' Equity (Details) (USD $)	1 Months Ended		12 Months Ended			63 Months Ended
	Sep. 30, 2012	Oct. 31, 2008	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
Stockholders' Equity
Increase in maximum amount approved under common stock repurchase program	$ 10,000,000
Maximum amount authorized under the common stock repurchase program		10,000,000
Shares of common stock repurchased			228,771			3,074,486
Aggregate cost of shares of common stock repurchased			2,151,000	1,633,000	3,910,000	16,500,000
Available authorized repurchase amount			$ 3,500,000