Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets:
Self insurance reserves	$ 7,464	$ 8,369
Contract loss reserves	240	72
Stock-based awards	3,986	4,420
Bonus	2,497	2,578
Other	960	886
Total deferred income tax assets	15,147	16,325
Deferred income tax liabilities:
Property and equipment - tax over book depreciation	(25,859)	(25,350)
Intangible assets - tax over book amortization	(3,670)	(3,799)
Total deferred income tax liabilities	(29,529)	(29,149)
Net deferred income taxes	$ (14,382)	$ (12,824)