Fair Value Measurements - Fair Value Hierarchy (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair value of assets and liabilities measured on a recurring basis
Total Assets	$ 311,302	$ 102,144
Total Liabilities	222,559	218,702
Acquisition Related Contingent Consideration | Lumara Health
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	214,895	206,600
Acquisition Related Contingent Consideration | MuGard
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	7,664	12,102
Money market funds
Fair value of assets and liabilities measured on a recurring basis
Total Assets	73,676	77,254
Corporate debt securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	200,677	24,890
Commercial paper.
Fair value of assets and liabilities measured on a recurring basis
Total Assets	34,449
Municipal securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	2,500
Fair Value, Inputs, Level 1
Fair value of assets and liabilities measured on a recurring basis
Total Assets	73,676	77,254
Fair Value, Inputs, Level 1 | Money market funds
Fair value of assets and liabilities measured on a recurring basis
Total Assets	73,676	77,254
Fair Value, Inputs, Level 2
Fair value of assets and liabilities measured on a recurring basis
Total Assets	237,626	24,890
Fair Value, Inputs, Level 2 | Corporate debt securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	200,677	24,890
Fair Value, Inputs, Level 2 | Commercial paper.
Fair value of assets and liabilities measured on a recurring basis
Total Assets	34,449
Fair Value, Inputs, Level 2 | Municipal securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	2,500
Fair Value, Inputs, Level 3
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	222,559	218,702
Fair Value, Inputs, Level 3 | Acquisition Related Contingent Consideration | Lumara Health
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	214,895	206,600
Fair Value, Inputs, Level 3 | Acquisition Related Contingent Consideration | MuGard
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	$ 7,664	$ 12,102