Share-Based Compensation - Options Exercisable and Expected to Vest (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 4.26
Range of exercise prices, upper range limit	$ 46.97
Exercisable Options, Stock Options, Shares	3,548,926
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	4 years 2 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 22.21
Options Expected to Vest, Stock Options, Number	2,017,616
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	8 years 7 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 7.79
$4.26 to $6.16
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 4.26
Range of exercise prices, upper range limit	$ 6.16
Exercisable Options, Stock Options, Shares	0
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 0.00
Options Expected to Vest, Stock Options, Number	900,302
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	9 years 5 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 5.76
$6.17 to $14.15
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	$ 14.15
Exercisable Options, Stock Options, Shares	1,578,296
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	6 years 0 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 9.76
Options Expected to Vest, Stock Options, Number	1,117,314
Options Expected to Vest, Weighted Average Remaining Contractual Life (Years)	8 years 0 months 12 days
Options Expected to Vest, Weighted Average Exercise Price	$ 9.43
$14.16 to $19.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower range limit	$ 14.16
Range of exercise prices, upper range limit	$ 19.20
Exercisable Options, Stock Options, Shares	0
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	0 years 0 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 0.00
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
$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	13,000
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	5 years 7 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 20.62
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	749,952
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	3 years 9 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 24.43
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	863,713
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	2 years 0 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 35.33
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	310,965
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	2 years 2 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 41.34
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	33,000
Exercisable Options, Weighted Average Remaining Contractual Life (Years)	0 years 7 months 12 days
Exercisable Options, Weighted Average Exercise Price	$ 44.34
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