Balance Sheet Components - Other Accured Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Components
Settlement accrued for reimbursement related claims	$ 10,062
Reserves for refunds to insurance carriers	6,794	$ 7,535
Accrued charges for outsourced testing	6,566	3,261
Testing and laboratory materials from suppliers	1,367	543
Marketing and corporate affairs	1,456	202
Legal, audit and consulting fees	206	180
Accrued shipping charges	198	467
Sales tax payable	504	459
Accrued specimen service fees	683	469
Accrued rent	856	195
Clinical trials and studies	483	388
Leasehold improvement projects in progress		1,659
Other accrued expenses	4,032	4,521
Total other accrued liabilities	33,207	$ 19,879
Accrued settlement liability	11,400
Accrued settlement liability, current	10,100
Accrued settlement liability, long-term	1,300
Additional reserves for refunds to insurance carriers	4,200
Revenue recognized	$ 4,900