Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES
Net income	$ 83,072	$ 87,362	$ 72,324
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	43,176	40,389	32,196
Interest accretion of convertible notes discount	10,662	9,854	9,109
Financing costs amortization	1,392	1,306	1,530
Employee share-based compensation expense	9,420	9,989	7,461
Impairment of intangible assets	0	0	3,070
Unrealized foreign currency transaction (gain) loss	(1,606)	(3,388)	96
Deferred income tax benefit	(248)	(1,607)	(4,518)
Reversal of contingent consideration liability	0	0	(4,620)
Other non-cash operating activities	(170)	4,514	6,165
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	43,079	(69,287)	3,422
Inventory	(8,150)	(12,679)	(15,777)
Unbilled contract revenues and other assets	(51,467)	(10,875)	(7,465)
Accounts payable and other liabilities	11,660	(5,259)	2,936
Deferred income taxes	(3,690)	(793)	663
Customer advances and billings in excess of contract revenue	(18,413)	10,137	(18,951)
Net Cash Provided By Operating Activities	118,717	59,663	87,641
INVESTING ACTIVITIES
Capital expenditures	(62,135)	(72,585)	(43,685)
Proceeds from sale of assets	1,593	569	2,073
Acquisition of businesses, net of cash acquired	(11,943)	(2,965)	(182,450)
Other investing activities	0	0	(285)
Net Cash Used In Investing Activities	(72,485)	(74,981)	(224,347)
FINANCING ACTIVITIES
Proceeds from long-term debt	0	0	21,375
Borrowings on revolving credit facilities	88,819	214,623	73,012
Repayments on revolving credit facilities	(87,162)	(211,403)	(77,770)
Payments on long-term debt	(68,437)	(3,750)	(4,438)
Payments for debt issuance costs	(1,321)	0	(1,445)
Payment of contingent consideration	(741)	0	(1,300)
Proceeds from exercise of stock options	763	5,335	3,519
Excess tax benefit from exercise of stock options	1,859	6,673	8,972
Common stock repurchases	(3,367)	(2,002)	(4,484)
Dividend distribution to noncontrolling interest	(1,206)	(1,369)	0
Net Cash (Used In) Provided By Financing Activities	(70,793)	8,107	17,441
Effect of exchange rate changes on cash	(9,128)	3,058	3,902
Net decrease in cash and cash equivalents	(33,689)	(4,153)	(115,363)
Cash and cash equivalents at beginning of period	137,345	141,498	256,861
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 103,656	$ 137,345	$ 141,498