Additional Balance Sheet Detail (Tables)

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

Summary of Prepaid and other current assets

Prepaid and other current assets consisted of the following:

	As of December 31,
	2017		2016
	(in thousands)
Prepaid expenses	$	62,475	$	36,134
Collaborative accounts receivable	28,907		719
Other receivables and assets	74,253		34,400
Total	$	165,635	$	71,253

Summary of Accrued expenses and other current liabilities

Accrued expenses consisted of the following:

	As of December 31,
	2017		2016
	(in thousands)
Payroll and benefits	$	113,026	$	86,387
Research, development and commercial contract costs	98,411		62,756
Product revenue allowances	119,919		86,533
Royalty payable	73,044		52,845
Other	39,561		26,728
Total	$	443,961	$	315,249