Condensed Consolidated Statements of Cumulative Redeemable Preferred Shares, Shareholders' Equity and Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	Total	Previously Reported	Retroactive application of recapitalization	Ordinary Shares	Ordinary Shares Previously Reported	Ordinary Shares Retroactive application of recapitalization	Treasury Shares	Treasury Shares Previously Reported	Treasury Shares Retroactive application of recapitalization	Paid-In Capital	Paid-In Capital Previously Reported	Paid-In Capital Retroactive application of recapitalization	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Previously Reported	Accumulated Deficit	Accumulated Deficit Previously Reported
Beginning balance (in shares) at Dec. 31, 2016				50,481,822	60,249,330	(9,767,508)	0	5,373,884	(5,373,884)
Beginning balance at Dec. 31, 2016	$ 170,603	$ 170,603	$ 0	$ 5,386	$ 656	$ 4,730	$ 0	$ (23,108)	$ 23,108	$ 349,358	$ 377,196	$ (27,838)	$ (3,719)	$ (3,719)	$ (180,422)	$ (180,422)
Shareholders' Equity
Net income for the period	17,109														17,109
Benefit obligation loss, net of tax	(42)												(42)
Recapitalization transaction (in shares)				52,982,364
Recapitalization transaction	433,531			$ 5,653						427,878
Dividends on cumulative redeemable preferred shares	(7,922)									(7,922)
Issuance of ordinary shares in exchange for warrants (in shares)				6,593,321
Issuance of ordinary shares in exchange for warrants	0			$ 736						143					(879)
Share-based compensation (in shares)				51,569
Share-based compensation	960			$ 5						955
Ending balance (in shares) at Jun. 30, 2017				110,109,076			0
Ending balance at Jun. 30, 2017	$ 614,239			$ 11,780			$ 0			770,412			(3,761)		(164,192)
Beginning balance (in shares) at Dec. 31, 2016	28,510,994	28,510,994
Beginning balance at Dec. 31, 2016	$ 345,951	$ 345,951
Cumulative Redeemable Preferred Shares
Dividends on cumulative redeemable preferred shares	$ 7,922
Purchase of cumulative redeemable preferred shares (in shares)	(28,510,994)
Purchase of cumulative redeemable preferred shares	$ (239,492)
Settlement of accrued dividends of cumulative redeemable preferred shares	$ (114,381)
Ending balance (in shares) at Jun. 30, 2017	0
Ending balance at Jun. 30, 2017	$ 0
Beginning balance (in shares) at Dec. 31, 2017				110,297,697			7,367
Beginning balance at Dec. 31, 2017	599,549			$ 11,803			$ (80)			773,194			(3,826)		(181,542)
Shareholders' Equity
Net income for the period	38,638														38,638
Benefit obligation loss, net of tax	(63)												(63)
Shares issued in business combination (see Note 4) (in shares)				20,000,000
Shares issued in business combination (see Note 4)	215,400			$ 2,336						213,064
Share-based compensation (in shares)				181,296
Share-based compensation	3,890			$ 21						3,869
Ending balance (in shares) at Jun. 30, 2018				130,478,993			7,367
Ending balance at Jun. 30, 2018	$ 857,414			$ 14,160			$ (80)			$ 990,127			$ (3,889)		$ (142,904)
Beginning balance (in shares) at Dec. 31, 2017	0
Beginning balance at Dec. 31, 2017	$ 0
Cumulative Redeemable Preferred Shares
Settlement of accrued dividends of cumulative redeemable preferred shares	$ 0
Ending balance (in shares) at Jun. 30, 2018	0
Ending balance at Jun. 30, 2018	$ 0