Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Total	Restricted Stock Units	Common Stock	Restricted Stock Units Restricted Stock Units	Additional Paid-in Capital	Exchangeable Shares of Subsidiary	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the change in accounting principle related to revenue recognition							$ (7,645,000)
Retained earnings, beginning of the period, as adjusted							29,950,000
Beginning Balance at Dec. 31, 2017			$ 438,000	$ 80,512,000	$ 800,806,000	$ 1,958,000	37,595,000	$ (22,222,000)	$ (690,785,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued			9,000		33,886,000
Restricted stock units recognized, net of forfeitures				8,463,000
Restricted stock units delivered				(34,104,000)
Exchangeable shares of subsidiary delivered						0
Dividends							(1,687,000)
Net income (loss)	$ 6,368,000						6,368,000
Currency translation adjustment, net of tax								(834,000)
Repurchased		$ (6,700,000)							(34,753,000)
Ending Balance at Mar. 31, 2018	178,005,000		447,000	54,871,000	834,692,000	1,958,000	34,631,000	(23,056,000)	(725,538,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the change in accounting principle related to revenue recognition							0
Retained earnings, beginning of the period, as adjusted							63,427,000
Beginning Balance at Dec. 31, 2018	62,363,000		450,000	71,596,000	846,721,000	1,958,000	63,427,000	(35,705,000)	(886,084,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued			12,000		34,203,000
Restricted stock units recognized, net of forfeitures				10,018,000
Restricted stock units delivered				(34,400,000)
Exchangeable shares of subsidiary delivered						0
Dividends							(1,346,000)
Net income (loss)	(15,386,000)						(15,386,000)
Currency translation adjustment, net of tax								1,054,000
Repurchased		$ (12,700,000)	(436,885)						(24,401,000)
Ending Balance at Mar. 31, 2019	$ 32,117,000		$ 462,000	$ 47,214,000	$ 880,924,000	$ 1,958,000	$ 46,695,000	$ (34,651,000)	$ (910,485,000)