Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax assets-
Accounts receivable and allowance for doubtful accounts	$ 1,627	$ 1,889
Stock compensation	3,036	3,080
Accrued liabilities and expenses	23,000	19,174
State net operating loss carryforwards	5,053	6,781
Goodwill	875
Other	759	830
Total deferred income tax assets	34,350	31,754
Deferred income tax liabilities-
Property and equipment	(4,398)	(5,572)
Long-term contracts	(637)	(728)
Goodwill		(6,037)
Intangible assets	(737)	(156)
Other	(513)	(357)
Total deferred income tax liabilities	(6,285)	(12,850)
Less-Valuation allowance	(3,184)	(4,438)
Net deferred income tax assets	24,881	14,466
Deferred income tax assets-
Deferred income tax assets	27,170	16,276
Deferred income tax liabilities-
Deferred tax liabilities	$ 2,289	$ 1,810