Significant Accounting Policies, Stock-Based Compensation Expense (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Allocation of stock-based compensation expense
Stock-based compensation expense	$ 8,118,000	$ 2,812,000	$ 22,894,000	$ 8,318,000
Stock Option [Member]
Allocation of stock-based compensation expense
Unrecognized estimated non-cash stock-based compensation expense	26,400,000		26,400,000
Weighted average period of amortization			1 year 3 months 18 days
RSUs [Member]
Allocation of stock-based compensation expense
Vesting period			4 years
Unrecognized estimated non-cash stock-based compensation expense	11,500,000		11,500,000
Weighted average period of amortization			1 year 6 months
RSUs [Member] | Employees [Member]
Allocation of stock-based compensation expense
Weighted-average grant date fair value (in dollars per share)			$ 45.80
RSUs [Member] | Board of Directors [Member]
Allocation of stock-based compensation expense
Weighted-average grant date fair value (in dollars per share)			$ 38.10
Research, Development and Patent Expenses [Member]
Allocation of stock-based compensation expense
Stock-based compensation expense	6,606,000	2,373,000	18,879,000	7,171,000
General and Administrative [Member]
Allocation of stock-based compensation expense
Stock-based compensation expense	$ 1,512,000	$ 439,000	$ 4,015,000	$ 1,147,000