Summary of Significant Accounting Policies - Revenue by Contract Type (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Revenue by External Customer [Line Items]
Revenue percent	100.00%	100.00%	100.00%
Time-and-material [Member]
Schedule of Revenue by External Customer [Line Items]
Revenue percent	86.20%	88.80%	90.30%
Progress Billing [Member]
Schedule of Revenue by External Customer [Line Items]
Revenue percent	11.20%	8.80%	7.90%
Percentage-of-completion [Member]
Schedule of Revenue by External Customer [Line Items]
Revenue percent	2.60%	2.40%	1.80%