Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 40,518	$ 123,385	$ 26,762
Other comprehensive (loss) income:
Reclassification adjustment for gains on sales of assets included in net income	0	0	435
Foreign currency translation	(74)	(87)	603
Total other comprehensive (loss) income	(74)	(87)	1,038
Comprehensive income	$ 40,444	$ 123,298	$ 27,800