Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Recorded Amount of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table sets forth the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 (in thousands):

Description	Total		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
March 31, 2019
Assets:
Cash and cash equivalents	$	221,738	$	214,346	$	7,392	$	—
Marketable securities:
U.S. government agency securities and treasuries		1,357,845		—		1,357,845		—
Certificates of deposit		5,960		—		5,960		—
Commercial paper		42,542		—		42,542		—
Corporate bonds		83,598		—		83,598		—
Equity securities		19,083		19,083		—		—
Total assets	$	1,730,766	$	233,429	$	1,497,337	$	—
Liabilities:
Contingent consideration	$	5,526	$	—	$	—	$	5,526
Total liabilities	$	5,526	$	—	$	—	$	5,526
December 31, 2018
Assets:
Cash and cash equivalents	$	402,579	$	348,638	$	53,941	$	—
Marketable securities:
U.S. government agency securities and treasuries		1,457,601		—		1,457,601		—
Certificates of deposit		9,080		—		9,080		—
Equity securities		22,167		22,167		—		—
Total assets	$	1,891,427	$	370,805	$	1,520,622	$	—
Liabilities:
Contingent consideration	$	5,230	$	—	$	—	$	5,230
Total liabilities	$	5,230	$	—	$	—	$	5,230

Roll-Forward of Fair Value of the Company's Contingent Consideration Obligations

The table below provides a roll-forward of fair value of the Company’s contingent consideration obligations, which include Level 3 inputs (in thousands):

	For the three months ended
	March 31, 2019
Beginning balance	$	5,230
Additions		—
Changes in fair value		296
Payments		—
Ending balance	$	5,526