Summary of Significant Accounting Principles - Prior Period Adjustment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss	$ (1,808)	$ (1,208)
Contract revenues	138,757	129,623
Costs of contract revenues	125,772	114,912
Selling, general and administrative expenses	14,979	15,538
Income tax expense	$ (1,019)	$ (750)