Stockholders' Equity (Details 4) (USD $)			6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Stock options
Number of Shares
Outstanding at the beginning of the period (in shares)	2,308,000	1,956,000	1,956,000
Granted (in shares)			731,000
Exercised (in shares)			(295,000)
Cancelled (in shares)			(84,000)
Outstanding at the end of the period (in shares)	2,308,000	1,956,000	2,308,000
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)			$ 5.86
Granted (in dollars per share)			$ 23.63
Exercised (in dollars per share)			$ 2.17
Cancelled (in dollars per share)			$ 15.52
Outstanding at the end of the period (in dollars per share)			$ 11.60