Unaudited Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance at Dec. 31, 2018	$ 1,439,768	$ 718	$ 1,097,758	$ 1,029,518	$ (71,397)	$ (616,829)
Increase (Decrease) in Stockholders' Equity
Net loss	(14,648)			(14,648)
Currency translation adjustments (excluding intercompany advances)	2,553				2,553
Currency translation adjustments on intercompany advances	(87)				(87)
Stock-based compensation expense:
Restricted stock	4,372	7	4,365
Stock options	53		53
Stock repurchases	(757)					(757)
Surrender of stock to settle taxes on restricted stock awards	(3,610)					(3,610)
Ending Balance at Mar. 31, 2019	1,427,644	725	1,102,176	1,014,870	(68,931)	(621,196)
Beginning Balance at Dec. 31, 2019	1,223,967	726	1,114,521	797,710	(67,746)	(621,244)
Increase (Decrease) in Stockholders' Equity
Net loss	(405,041)			(405,041)
Currency translation adjustments (excluding intercompany advances)	(6,085)				(6,085)
Currency translation adjustments on intercompany advances	(8,706)				(8,706)
Stock-based compensation expense:
Restricted stock	1,162	6	1,156
Surrender of stock to settle taxes on restricted stock awards	(2,665)					(2,665)
Ending Balance at Mar. 31, 2020	$ 802,632	$ 732	$ 1,115,677	$ 392,669	$ (82,537)	$ (623,909)