Equity Transactions (Details) - USD ($)			1 Months Ended		3 Months Ended			9 Months Ended
	Apr. 28, 2020	Feb. 21, 2020	Aug. 31, 2020	Feb. 29, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Maximum aggregate offering price of securities under shelf registration				$ 250,000
Ordinary shares, nominal value (in usd per share)				$ 0.01	$ 0.01			$ 0.01		$ 0.01
Preferred shares, nominal value (in usd per share)				$ 0.01	$ 0.01			$ 0.01		$ 0.01
Maximum aggregate offering price of ADSs under shelf registration				$ 50,000
Stock transaction issuance costs				$ 428,000
Prepaid expenses and other current assets					$ 47,054,000			$ 47,054,000		$ 4,264,000
February 2020 private placement					(69,000)	$ (94,000)	$ 60,733,000
Proceeds from the February 2020 private placement								60,570,000	$ 0
Maximum threshold percentage for trigger of convertible preferred stock		9.99%
Additional paid-in capital
Class of Stock [Line Items]
Amortization costs								214,000
Prepaid expenses and other current assets					214,000			$ 214,000
February 2020 private placement					$ (69,000)	$ (94,000)	60,641,000
Issuance costs		$ 4,430,000
Treasury Stock, Retired, Cost Method, Amount			$ 49,944,000
Ordinary shares
Class of Stock [Line Items]
February 2020 private placement							$ 87,000
February 2020 private placement (in shares)							8,680,000
Treasury Stock, Retired, Cost Method, Amount			54,000
Treasury Stock, Shares, Retired					5,407,000
Treasury shares
Class of Stock [Line Items]
Treasury Stock, Retired, Cost Method, Amount			$ (49,998,000)
Treasury Stock, Shares, Retired					5,407,000
Securities Purchase Agreement
Class of Stock [Line Items]
February 2020 private placement		65,000,000
Proceeds from the February 2020 private placement		$ 60,570,000
American Depositary Receipts | Securities Purchase Agreement
Class of Stock [Line Items]
February 2020 private placement (in shares)		8,680,000
Series A Preferred Stock | Securities Purchase Agreement
Class of Stock [Line Items]
February 2020 private placement (in shares)		488
Shares issued, price per share (in dollars per share)		$ 7.09
American Depositary Shares | Public Offering
Class of Stock [Line Items]
Shares sold in offering	11,630,000
Offering price per share (in dollars per share)	$ 10.75
Gross proceeds from stock offering	$ 125,000,000
Aggregate net proceeds from stock offering	$ 116,924,000