Fair Value - Changes in Fair Value of Level 3 Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Preferred shares derivative liability, Beginning Balance			$ 69,810	$ 62,790
Preferred share derivative liability, Conversion			0	0
Preferred share derivative liability, Gain and remeasurement included in earnings	$ (8,391)	$ 2,490	(1,341)	2,940
Preferred shares derivative liability, Ending Balance	$ 68,469	65,730	$ 68,469	65,730
Fair Value, Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Continently Convertible Liability, Calculation [Roll Forward]
Contingently convertible Series E units liability, Beginning Balance				69,957
Contingently convertible Series E units liability, Conversions				(58,494)
Contingently convertible Series E units liability, Gain and remeasurement included in earnings				(11,463)
Contingently convertible Series E units liability, Ending Balance		$ 0		$ 0