Cash and Cash Equivalents and Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 7,466	$ 47,287	$ 54,488	$ 82,217
Payment for contingent consideration	2,400	$ 3,000
Avantec Heathcare Limited
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payment for contingent consideration			$ 3,000
Contingent consideration liability	$ 2,400