Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Fair value of assets and liabilities measured on a recurring basis
Transfers or reclassifications of securities from Level 1 to Level 2	$ 0
Transfers or reclassifications of securities from Level 2 to Level 1	0
Fair Value, Measurements, Recurring
Fair value of assets and liabilities measured on a recurring basis
Total Assets	314,388,000	$ 311,302,000
Total Liabilities	223,809,000	222,559,000
Fair Value, Measurements, Recurring | Acquisition Related Contingent Consideration | Lumara Health
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	221,449,000	214,895,000
Fair Value, Measurements, Recurring | Acquisition Related Contingent Consideration | MuGard
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	2,360,000	7,664,000
Fair Value, Measurements, Recurring | Money market funds
Fair value of assets and liabilities measured on a recurring basis
Total Assets	19,029,000	73,676,000
Fair Value, Measurements, Recurring | Corporate debt securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	254,228,000	200,677,000
Fair Value, Measurements, Recurring | U.S. treasury and government agency securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	5,986,000
Fair Value, Measurements, Recurring | Commercial paper.
Fair value of assets and liabilities measured on a recurring basis
Total Assets	32,644,000	34,449,000
Fair Value, Measurements, Recurring | Municipal securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	2,501,000	2,500,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair value of assets and liabilities measured on a recurring basis
Total Assets	19,029,000	73,676,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Money market funds
Fair value of assets and liabilities measured on a recurring basis
Total Assets	19,029,000	73,676,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair value of assets and liabilities measured on a recurring basis
Total Assets	295,359,000	237,626,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Corporate debt securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	254,228,000	200,677,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | U.S. treasury and government agency securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	5,986,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Commercial paper.
Fair value of assets and liabilities measured on a recurring basis
Total Assets	32,644,000	34,449,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Municipal securities
Fair value of assets and liabilities measured on a recurring basis
Total Assets	2,501,000	2,500,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	223,809,000	222,559,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Acquisition Related Contingent Consideration | Lumara Health
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	221,449,000	214,895,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Acquisition Related Contingent Consideration | MuGard
Fair value of assets and liabilities measured on a recurring basis
Total Liabilities	$ 2,360,000	$ 7,664,000