Stock Options and Restricted Stock Stoct Options Outsanding and Exercisable By Exercise Price Range (Details) (USD $)	6 Months Ended
	Jun. 30, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	9,241,992
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	6 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 11.33
Options Exercisable and Vested, Number of Shares	5,780,981
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 8.09
$1.00 - $1.40 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	971,103
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	2 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 1.16
Options Exercisable and Vested, Number of Shares	971,103
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 1.16
Exercise Price, Lower Limit (usd per share)	$ 1.00
Exercise Price, Upper Limit (usd per share)	$ 1.40
$2.98 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	216,240
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	4 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 2.98
Options Exercisable and Vested, Number of Shares	216,240
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 2.98
Exercise Price (usd per share)	$ 2.98
$ 5.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	1,362,500
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	4 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 5.00
Options Exercisable and Vested, Number of Shares	1,362,500
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 5.00
Exercise Price (usd per share)	$ 5.00
$7.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	1,737,000
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	7 years
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 7.50
Options Exercisable and Vested, Number of Shares	1,284,822
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 7.50
Exercise Price (usd per share)	$ 7.50
$11.29 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	255,000
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	7 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 11.29
Options Exercisable and Vested, Number of Shares	166,041
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 11.29
Exercise Price (usd per share)	$ 11.29
$13.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	955,000
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	7 years 6 months
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 13.00
Options Exercisable and Vested, Number of Shares	562,597
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 13.00
Exercise Price (usd per share)	$ 13.00
$14.82 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	1,905,316
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	8 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 14.82
Options Exercisable and Vested, Number of Shares	840,814
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 14.82
Exercise Price (usd per share)	$ 14.82
$15.50 - $21.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	1,153,333
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	8 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 19.03
Options Exercisable and Vested, Number of Shares	355,614
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 17.87
Exercise Price, Lower Limit (usd per share)	$ 15.50
Exercise Price, Upper Limit (usd per share)	$ 21.00
$25.50 - $26.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	686,500
Options Outstanding Weighted Average Remaining Contractual Life (in Years)	9 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (usd per share)	$ 25.74
Options Exercisable and Vested, Number of Shares	21,250
Options Exercisable and Vested, Weighted-Average Exercise Price (usd per share)	$ 25.50
Exercise Price, Lower Limit (usd per share)	$ 25.50
Exercise Price, Upper Limit (usd per share)	$ 26.50