Share-Based Compensation - Options Exercisable and Expected to Vest (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 3.48
Range of exercise prices, upper range limit	$ 46.97
Exercisable Options, Stock Options, Shares	3,360,673
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	4 years 8 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 17.57
Options Expected to Vest, Stock Options, Number	1,814,171
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	8 years 4 months 24 days
Options Expected to Vest, Weighted Average Exercise Price	$ 5.73
$3.48 to $6.16
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 3.48
Range of exercise prices, upper range limit	$ 6.16
Exercisable Options, Stock Options, Shares	287,915
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	8 years 1 month 6 days
Exercisable Options, Weighted Average Exercise Price	$ 5.75
Options Expected to Vest, Stock Options, Number	1,381,213
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	8 years 9 months 18 days
Options Expected to Vest, Weighted Average Exercise Price	$ 4.57
$6.17 to $9.64
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 6.17
Range of exercise prices, upper range limit	$ 9.64
Exercisable Options, Stock Options, Shares	509,312
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	5 years 8 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 8.60
Options Expected to Vest, Stock Options, Number	77,456
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	7 years 10 months 24 days
Options Expected to Vest, Weighted Average Exercise Price	$ 7.12
$9.65 to $19.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 9.65
Range of exercise prices, upper range limit	$ 19.20
Exercisable Options, Stock Options, Shares	1,325,913
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	5 years 7 months 6 days
Exercisable Options, Weighted Average Exercise Price	$ 10.10
Options Expected to Vest, Stock Options, Number	355,502
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	7 years
Options Expected to Vest, Weighted Average Exercise Price	$ 9.96
$19.21 to $23.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 19.21
Range of exercise prices, upper range limit	$ 23.95
Exercisable Options, Stock Options, Shares	9,500
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	4 years 2 months 15 days
Exercisable Options, Weighted Average Exercise Price	$ 20.20
Options Expected to Vest, Stock Options, Number	0
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 0.00
$23.96 to $28.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 23.96
Range of exercise prices, upper range limit	$ 28.70
Exercisable Options, Stock Options, Shares	521,320
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	3 years 2 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 24.49
Options Expected to Vest, Stock Options, Number	0
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 0.00
$28.71 to $39.38
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 28.71
Range of exercise prices, upper range limit	$ 39.38
Exercisable Options, Stock Options, Shares	475,438
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	1 year 9 months 18 days
Exercisable Options, Weighted Average Exercise Price	$ 36.01
Options Expected to Vest, Stock Options, Number	0
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 0.00
$39.39 to $41.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 39.39
Range of exercise prices, upper range limit	$ 41.75
Exercisable Options, Stock Options, Shares	228,775
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	1 year 6 months
Exercisable Options, Weighted Average Exercise Price	$ 41.24
Options Expected to Vest, Stock Options, Number	0
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 0.00
$41.76 to $46.97
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 41.76
Range of exercise prices, upper range limit	$ 46.97
Exercisable Options, Stock Options, Shares	2,500
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	2 years 4 months 24 days
Exercisable Options, Weighted Average Exercise Price	$ 45.76
Options Expected to Vest, Stock Options, Number	0
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 0.00