Summary of Significant Accounting Principles - Prior Period Adjustment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 4,739	$ (7,396)	$ 2,723	$ (9,498)
Contract revenues	164,017	137,061	433,941	304,607
Costs of contract revenues	139,849	128,783	378,116	281,848
Selling, general and administrative expenses	15,291	14,496	47,728	31,982
Income tax expense	3,224	$ (1,669)	1,972	$ (2,945)
Restatement Adjustment | Accounting Errors
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	400		400
Contract revenues	4,800		4,800
Costs of contract revenues	4,200		4,200
Selling, general and administrative expenses	100		100
Income tax expense	$ 100		$ 100