Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets (liabilities):
Net operating loss carryforwards	$ 70,247	$ 47,053
Accrued expenses	1,088	926
Stock-based compensation	2,238	451
Amortization of debt restructure cost	2,718
Amortization of intangible assets	(6,908)	(3,072)
Depreciation of property and equipment	(28)	(152)
Valuation allowance	(71,202)	(46,477)
Other	153	86
Net deferred tax assets (liabilities)	$ (1,694)	$ (1,185)