Additional Balance Sheet Detail

12 Months Ended

Dec. 31, 2018

Prepaid and other current assets consisted of the following:



	As of December 31,
	2018		2017
	(in thousands)
Prepaid expenses	$	74,045	$	62,475
Collaborative accounts receivable	5,182		28,907
Other receivables and assets	61,592		75,742
Total	$	140,819	$	167,124

Accrued expenses consisted of the following:



	As of December 31,
	2018		2017
	(in thousands)
Payroll and benefits	$	124,753	$	113,026
Research, development and commercial contract costs	115,300		98,411
Product revenue allowances	195,598		119,919
Royalty payable	101,108		73,044
Other	67,736		39,561
Total	$	604,495	$	443,961