Fair Value of Financial Assets and Liabilities - Rollforward of Liabilities Measured by Level 3 Inputs (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
	Jan. 26, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Rollforward of Liabilities Measured by Level 3 Inputs:
Reclassification to equity	$ (5,203)		$ (5,203)		$ 0
Issuance of common shares in settlement of contingent equity liability		$ 0		$ (32,020)
Warrant Liability
Rollforward of Liabilities Measured by Level 3 Inputs:
Beginning balance			4,021		780	$ 4,021	$ 780
Change in fair value						1,182	5,509
Reclassification to equity						(5,203)
Issuance of common shares in settlement of contingent equity liability							0
Ending balance						0	6,289
Derivative Liability
Rollforward of Liabilities Measured by Level 3 Inputs:
Beginning balance			0		512	0	512
Change in fair value						0	(512)
Reclassification to equity						0
Issuance of common shares in settlement of contingent equity liability							0
Ending balance						0	0
Contingent Equity Liability
Rollforward of Liabilities Measured by Level 3 Inputs:
Beginning balance			$ 0		$ 18,938	0	18,938
Change in fair value						0	13,082
Reclassification to equity						0
Issuance of common shares in settlement of contingent equity liability							(32,020)
Ending balance						$ 0	$ 0