CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Ordinary share capital	Additional paid-in capital	Retained earnings (deficit)	Retained earnings (deficit) Cumulative effect of adoption of accounting guidance for expected credit losses at January 1, 2020
Beginning balance at Dec. 31, 2018		$ 3,638	$ 499,726	$ (26,077)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of Class A ordinary shares, net of forfeitures		61
Share-based compensation expense			2,835
Net income (loss)	$ 26,360			26,360
Ending balance at Sep. 30, 2019	506,543	3,699	502,561	283
Beginning balance at Jun. 30, 2019		3,679	501,916	(4,857)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of Class A ordinary shares, net of forfeitures		20
Share-based compensation expense			645
Net income (loss)	5,140			5,140
Ending balance at Sep. 30, 2019	506,543	3,699	502,561	283
Beginning balance at Dec. 31, 2019	477,183	3,699	503,547	(30,063)	$ (886)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of Class A ordinary shares, net of forfeitures		25
Repurchase of Class A ordinary shares		(187)	(12,484)
Share-based compensation expense			1,366
Net income (loss)	(38,150)			(38,150)
Ending balance at Sep. 30, 2020	$ 426,867	3,537	492,429	(69,099)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance at Jun. 30, 2020		3,627	497,559	(71,282)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of Class A ordinary shares, net of forfeitures		(19)
Repurchase of Class A ordinary shares		(71)	(4,828)
Share-based compensation expense			(302)
Net income (loss)	$ 2,183			2,183
Ending balance at Sep. 30, 2020	$ 426,867	$ 3,537	$ 492,429	$ (69,099)