Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable
Billed accounts receivable				$ 115,068	$ 134,040
Unbilled - scheduled billings				28,826	22,258
Costs and estimated earnings in excess of billings				27,737	19,994
Accounts receivable, gross				171,631	176,292
Less allowance for doubtful accounts	$ (2,842)	$ (2,335)	$ (1,752)	(2,130)	(2,842)
Accounts receivable, net				$ 169,501	$ 173,450
Activity in the allowance for doubtful accounts
Balance at beginning of period	2,842	2,335	1,752
Additions Charge to cost and expense	311	730	1,813
Deductions Write-offs	(905)	(24)	(1,312)
Effect of foreign exchange rate changes	(118)	(199)	82
Balance at end of period	$ 2,130	$ 2,842	$ 2,335
Accounts Receivable Greater Than 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk percentage	9.00%	5.00%