Stockholders' Equity (Details) (USD $)	1 Months Ended		3 Months Ended	54 Months Ended
	Sep. 30, 2012	Oct. 31, 2008	Mar. 31, 2013	Mar. 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			218,144	2,828,412
Aggregate cost of shares of common stock repurchased			1,600,000	14,200,000
Available authorized repurchase amount			$ 5,800,000