Summary of Significant Accounting Principles - Prior Period Adjustment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net (loss) income	$ (1,633)	$ 2,249	$ (9,557)	$ 6,350
Contract revenues	165,985	159,767	309,090	296,610
Costs of contract revenues	151,008	140,305	285,031	262,452
Selling, general and administrative expenses	15,114	14,710	30,087	27,751
Income tax (benefit) expense	$ (140)	$ 1,660	$ 453	$ 3,149

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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