Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenues:
Product revenues	$ 92,625	$ 83,979
Operating expenses:
General and administrative	19,718	16,751
Net loss	(3,775)	$ (806)
Assets:
Accounts receivable, net	46,567			$ 31,161
Equity:
Accumulated deficit	(235,777)			$ (245,945)
Balance Without Adoption of ASC 606 | ASU 2014-09
Revenues:
Product revenues	94,040
Operating expenses:
General and administrative	20,742
Net loss	(3,384)
Assets:
Accounts receivable, net	32,778
Equity:
Accumulated deficit	(249,509)
Adjustments | ASU 2014-09
Revenues:
Product revenues	(1,415)
Operating expenses:
General and administrative	(1,024)
Net loss	(391)
Assets:
Accounts receivable, net	13,789		$ 14,200
Equity:
Accumulated deficit	$ 13,732		$ 14,100