Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for doubtful accounts	$ (2,989)	$ (3,208)
Total	238,102	234,648
Contract changes, negotiated settlements and claims for unanticipated contract costs	900	4,561
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	144,616	141,481
U.S. Government [Member] | Billed Revenues [Member] | Contract Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	20,289	21,909
U.S. Government [Member] | Unbilled Revenues [Member] | Contract Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	4,248	1,581
Commercial and Other Government [Member] | Billed Revenues [Member] | Contract Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	68,066	51,166
Commercial and Other Government [Member] | Unbilled Revenues [Member] | Contract Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	$ 3,872	$ 21,719