Income Taxes - Schedule of Deferred Tax Assets and liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Operating loss and interest deduction carry forwards	$ 21,984	$ 24,580
Other	277	504
Total deferred tax assets	22,261	25,084
Valuation allowance	(3,444)	(11,101)
Total net deferred tax assets	18,817	13,983
Property and equipment	(12,359)	(4,336)
Net unbilled revenue	(1,633)	(6,113)
Partnership investments		(2,099)
Other	(300)	(1,320)
Total deferred tax liabilities	(14,292)	(13,868)
Net deferred tax asset (liability)	$ 4,525	$ 115