Significant Accounting Policies, Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	May. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 13,605	$ 7,708	$ 26,910	$ 14,777
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Unrecognized estimated non-cash stock-based compensation expense	57,500		$ 57,500
Weighted average period of amortization			1 year 4 months 24 days
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Vesting period			4 years
Unrecognized estimated non-cash stock-based compensation expense	$ 21,300		$ 21,300
Weighted average period of amortization			1 year 7 months 6 days
RSUs [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Weighted-average grant date fair value (in dollars per share)			$ 68.73
2011 Equity Incentive Plan [Member]
Amendments to Equity Plans [Abstract]
Number of shares authorized (in shares)	11.0		11.0		5.5
2002 Nonemployee Directors Stock Option Plan [Member]
Amendments to Equity Plans [Abstract]
Number of shares authorized (in shares)	2.0		2.0		1.2
Research, Development and Patent Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 10,465	6,401	$ 20,951	12,274
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,140	$ 1,307	$ 5,959	$ 2,503