Stock Incentive Plans - Information Related to Awards Outstanding and Exercisable (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards outstanding (in shares)	2,875,508
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 1 month 18 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 11.17
Stock awards exercisable (in shares)	1,055,172
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 7 months 18 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 21.40
$0.73 - $0.80
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 0.73
Range of Exercise/Grant Prices, Maximum	$ 0.80
Stock awards outstanding (in shares)	77,500
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 8 months 27 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 0.80
Stock awards exercisable (in shares)	6,250
Weighted average remaining contractual life, stock awards exercisable (in years)	8 years 8 months 23 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 0.80
$1.20 - $1.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 1.20
Range of Exercise/Grant Prices, Maximum	$ 1.74
Stock awards outstanding (in shares)	712,129
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 11 months 19 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 1.45
Stock awards exercisable (in shares)	25,000
Weighted average remaining contractual life, stock awards exercisable (in years)	8 years 8 months 12 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 1.20
$2.04 - $2.04
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 2.04
Range of Exercise/Grant Prices, Maximum	$ 2.04
Stock awards outstanding (in shares)	15,000
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 5 months 12 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 2.04
Stock awards exercisable (in shares)	3,750
Weighted average remaining contractual life, stock awards exercisable (in years)	8 years 5 months 12 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 2.04
$4.61 - $4.61
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 4.61
Range of Exercise/Grant Prices, Maximum	$ 4.61
Stock awards outstanding (in shares)	623,060
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 1 month 28 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 4.61
Stock awards exercisable (in shares)	37,472
Weighted average remaining contractual life, stock awards exercisable (in years)	8 years 1 month 28 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 4.61
$4.96 - $6.97
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 4.96
Range of Exercise/Grant Prices, Maximum	$ 6.97
Stock awards outstanding (in shares)	275,000
Weighted average remaining contractual life, stock awards outstanding (in years)	8 years 2 months 19 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 5.33
Stock awards exercisable (in shares)	31,250
Weighted average remaining contractual life, stock awards exercisable (in years)	8 years 2 months 1 day
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 5.76
$9.75 - $9.75
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 9.75
Range of Exercise/Grant Prices, Maximum	$ 9.75
Stock awards outstanding (in shares)	200,000
Weighted average remaining contractual life, stock awards outstanding (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 9.75
Stock awards exercisable (in shares)	100,000
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 9.75
$15.00 - $15.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 15.00
Range of Exercise/Grant Prices, Maximum	$ 15.00
Stock awards outstanding (in shares)	200,000
Weighted average remaining contractual life, stock awards outstanding (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 15.00
Stock awards exercisable (in shares)	200,000
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 15.00
$23.00 - $23.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 23.00
Range of Exercise/Grant Prices, Maximum	$ 23.00
Stock awards outstanding (in shares)	200,000
Weighted average remaining contractual life, stock awards outstanding (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 23.00
Stock awards exercisable (in shares)	200,000
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 23.00
$28.68 - $28.68
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 28.68
Range of Exercise/Grant Prices, Maximum	$ 28.68
Stock awards outstanding (in shares)	372,819
Weighted average remaining contractual life, stock awards outstanding (in years)	7 years 1 month 28 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 28.68
Stock awards exercisable (in shares)	251,450
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 1 month 28 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 28.68
$32.00 - $32.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise/Grant Prices, Minimum	$ 32.00
Range of Exercise/Grant Prices, Maximum	$ 32.00
Stock awards outstanding (in shares)	200,000
Weighted average remaining contractual life, stock awards outstanding (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards outstanding (in dollars per share)	$ 32.00
Stock awards exercisable (in shares)	200,000
Weighted average remaining contractual life, stock awards exercisable (in years)	7 years 8 months 5 days
Weighted average exercise/grant price per share, stock awards exercisable (in dollars per share)	$ 32.00