Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 31, 2017	Aug. 08, 2017	Dec. 31, 2015
Policies
Net (loss) income	$ (31,841)	$ (29,616)	$ (33,824)	$ (32,873)	$ (47,217)	$ (27,865)	$ (29,066)	$ (33,480)	$ (128,154)	$ (137,628)	$ (100,327)
Accumulated deficit	574,529				446,375				574,529	446,375
Cash and cash equivalents	46,407				12,620				46,407	12,620	15,256			$ 28,947
Marketable securities	107,461				106,247				107,461	106,247
Short-term Credit Line, outstanding balance	50,153				50,112				50,153	50,112
Long-term Term Loan, carrying amount	73,357				73,065				73,357	73,065
Total revenues	66,965	$ 65,280	$ 63,069	$ 62,340	52,050	$ 55,910	$ 52,283	$ 49,382	$ 257,654	209,625	$ 212,512
Agreement term									4 years
Restricted cash
Restricted cash, long term portion					342					342
2017 Term Loan
Policies
Long-term Term Loan, carrying amount	73,357				$ 73,065				$ 73,357	$ 73,065
Remaining borrowing capacity	$ 50,000								$ 50,000			$ 50,000	$ 25,000
Qiagen
Policies
Agreement term									10 years