Equity Incentive Plans - Schedule of Non-cash Share-Based Compensation Expenses Related to Company's Equity-Based Awards (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 10,206	$ 7,570	$ 18,726	$ 12,131	$ 27,116
Cost of Revenues
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	263	131	428	274	467
Research, Development and Clinical Trials
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	1,286	811	2,192	1,673	3,587
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	1,893	1,735	3,329	2,390	3,784
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 6,764	$ 4,893	$ 12,777	$ 7,794	$ 19,278