Fair Value - Summary of the Company's Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair value
Debt securities	$ 407,010
Contingent consideration	32,400	$ 65,200
Recurring Basis
Fair value
Cash equivalents	8,064	54,590
Contingent consideration	32,400	65,200
Common stock warrants		1,205
Assets, Total	447,474	470,649
Recurring Basis \| Level 1
Fair value
Cash equivalents	8,064	54,590
Assets, Total	81,859	114,697
Recurring Basis \| Level 2
Fair value
Assets, Total	331,262	289,055
Recurring Basis \| Level 3
Fair value
Contingent consideration	32,400	65,200
Common stock warrants		1,205
Assets, Total	34,353	66,897
U.S. government and agency debt securities \| Recurring Basis
Fair value
Debt securities	117,376	98,513
U.S. government and agency debt securities \| Recurring Basis \| Level 1
Fair value
Debt securities	73,795	60,107
U.S. government and agency debt securities \| Recurring Basis \| Level 2
Fair value
Debt securities	43,581	38,406
Corporate debt securities \| Recurring Basis
Fair value
Debt securities	195,855	173,637
Corporate debt securities \| Recurring Basis \| Level 2
Fair value
Debt securities	193,902	173,145
Corporate debt securities \| Recurring Basis \| Level 3
Fair value
Debt securities	1,953	492
International government agency debt securities \| Recurring Basis
Fair value
Debt securities	93,779	77,504
International government agency debt securities \| Recurring Basis \| Level 2
Fair value
Debt securities	$ 93,779	$ 77,504

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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Amount of asset recognized arising from contingent consideration in a business combination, expected to be realized beyond one year or the normal operating cycle, if longer.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

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