Stock-based Compensation and Awards Summary of stock option activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		12 Months Ended	0 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Stock Options	Dec. 31, 2011 Stock Options	Mar. 27, 2012 Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing stock price		$ 26.79
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Available for Grant, Outstanding, Beginning balance	1,101,111
Number of Options, Outstanding, Beginning balance	3,808,222
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 3.57
Weighted average remaining contractual term, Outstanding, Beginning balance		7 years 0 months 7 days	6 years 8 months 5 days
Aggregate intrinsic value, Outstanding, Beginning balance	$ 28,682
Shares Available for Grant, Shares removed from the plan	(167,166)
Shares Available for Grant, Options granted	(496,370)			(33,333)
Number of Options, Options granted	496,370			33,333
Weighted Average Exercise Price, Options granted	$ 22.27
Number of Options, Options exercised	(350,750)
Weighted Average Exercise Price, Options exercised	$ 1.36
Shares Available for Grant, Options canceled	26,989
Number of Options, Options canceled	(26,989)
Weighted Average Exercise Price, Options canceled	$ 4.26
Shares Available for Grant, Options expired	4,961
Number of Options, Options expired	(4,961)
Weighted Average Exercise Price, Options expired	$ 2.58
Shares Available for Grant, Early exercised options repurchased and added back to the pool	1,315
Weighted Average Exercise Price, Early exercised options repurchased and added back to the pool
Shares Available for Grant, Outstanding, Ending balance	470,840
Number of Options, Outstanding, Ending balance	3,921,892
Weighted Average Exercise Price, Outstanding, Ending balance	$ 6.13			$ 16.00
Weighted average remaining contractual term, Outstanding, Ending balance		7 years 0 months 7 days	6 years 8 months 5 days
Aggregate intrinsic value, Outstanding, Ending balance	$ 81,029			$ 200