Convertible Preference Shares (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Preferred Units [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares				90,220,000
Series 4 Convertible Preferred Stock [Domain]
Preferred Units [Line Items]
Proceeds from issuance of convertible preference shares				$ 95,000	$ 0
Convertible Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Preferred Units [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares		95,000		95,000		0
Preferred Stock, Value, Issued				$ 90,220
Accretion on convertible preferred shares	$ 1,948		$ 0	4,365	$ 0
Preferred Stock, Liquidation Preference, Value	$ 99,365			$ 99,365		$ 0
Preferred Stock, Conversion Basis, Common Stock Class A Closing Trade Price		125.00%