Stock Option and Compensation Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 item	Sep. 30, 2012
Stock Option and Compensation Plans
Number of option plans			2
Share-based compensation expense	$ 1,147,000	$ 150,000	$ 1,607,000	$ 283,000
2007 Plan
Stock Option and Compensation Plans
Increase in number of shares authorized under the Plan			1,878,343
Number of shares of common stock available for issuance under the Plan	739,317		739,317
Awards outstanding (in shares)	2,620,000		2,620,000
2013 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan	739,000		739,000
Annual increase in shares reserved for issuance under the Plan			2,542,372
Annual increase in shares reserved for issuance under the Plan (as a percent)			4.00%
2013 Plan | Maximum
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan	3,359,641		3,359,641
Stock option
Stock Option and Compensation Plans
Share-based compensation expense	1,100,000	200,000	1,600,000	300,000
Unrecognized share-based compensation costs	11,600,000		11,600,000
Expected weighted average period to recognize share-based compensation costs			3 years 4 months 24 days
Additional disclosure of vested and non-vested options
Outstanding vested options (in shares)	1,091,000		1,091,000
Intrinsic value of outstanding vested options	30,800,000		30,800,000
Closing price of the Company's stock (in dollars per share)	$ 29.71		$ 29.71
Weighted average exercise price of vested stock options (in dollars per share)	$ 1.36		$ 1.36
Outstanding unvested options (in shares)	1,529,000		1,529,000
Intrinsic value of outstanding unvested options	$ 30,500,000		$ 30,500,000
Weighted average exercise price of unvested stock options (in dollars per share)	$ 9.76		$ 9.76