CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 38,802	$ 8,731	$ 4,954
Other comprehensive income (loss), before income tax:
Unrealized foreign currency translation gain (loss)	75	(34)	(89)
Other comprehensive income (loss), net of tax	75	(34)	(89)
Comprehensive income	38,877	8,697	4,865
Less: Comprehensive income attributable to noncontrolling interest in subsidiary	1,289	764	536
Comprehensive income attributable to common shareholders	$ 37,588	$ 7,933	$ 4,329