Share-Based Compensation (Narrative) (Details) (USD $)	6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2011	Sep. 30, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option grants outstanding weighted average remaining contractual life, years		6.77
Number of options, outstanding		9,548,737
Shares sold to employees under Employee Stock Purchase Plan		16,991	48,909
Shares available for issuance under Employee Stock Purchase Plan		413,069
Employee Stock Purchase Plan fair value under Period One Plan	$ 77,000
Risk free interest rate under Employee Stock Purchase Plan	0.19%
Volatility rate under Employee Stock Purchase Plan	37.80%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares under option		1,778,278
Number of options, outstanding		9,548,737	8,553,332
Total unrecognized compensation cost related to unvested share-based payments		28,900,000
Weighted average period of total unrecognized compensation cost related to unvested share based payments granted, years		2.81
TSR Based PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares assumed for share-based compensation expense		16,928
TSR Based PSUs [Member] | Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per TSR PSU		$ 24.38
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested share-based payments		3,700,000
Weighted average period of total unrecognized compensation cost related to unvested share based payments granted, years		2.27
PSUs weighted-average grant date fair values		17.84
Fair value per TSR PSU		$ 18.50
Risk free interest rate under Employee Stock Purchase Plan		1.19%
Volatility rate under Employee Stock Purchase Plan		69.75%
Expected option life under Employee Stock Purchase Plan, years		2.99
Shares assumed for share-based compensation expense		253,721
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life under Employee Stock Purchase Plan, years	0.5
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested share-based payments		$ 180,000
Weighted average period of total unrecognized compensation cost related to unvested share based payments granted, years		0.39
Fair value per TSR PSU		$ 17.30
Minimum Exercise Price Of Options Grant Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option grants exercise prices range		$ 0.99
Maximum Exercise Price Of Options Grant Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option grants exercise prices range		$ 25.90
Black Scholes Option Pricing Model [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares under option		1,778,278
Weighted average fair value of stock options granted		$ 11.37