CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Cash Flows [Abstract]
Net income	$ 313,404	$ 398,628	$ 351,680
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	69,795	64,734	61,261
Stock-based compensation expense	20,813	26,019	26,134
Deferred income taxes	(10,228)	4,981	(7,054)
Loss on disposal of property, plant and equipment	232	587	812
Excess income tax benefits from exercise of stock options	(1,223)	(2,584)	(3,020)
Changes in operating assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	19,728	21,500	(17,413)
Inventories	45,340	20,147	(64,089)
Accounts payable	(18,932)	(76,650)	55,378
Accrued income taxes	(11,759)	21,740	23,763
Accrued liabilities and customer deposits	(11,338)	(14,837)	68,729
Other assets and liabilities	33,475	(16,005)	(23,796)
Net cash provided by operating activities	449,307	448,260	472,385
Investing Activities
Purchase of property, plant and equipment	(50,216)	(49,428)	(47,662)
Proceeds from disposal of property, plant and equipment	363	1,784	421
Acquisitions of business, net of cash acquired	(183,113)	(129,550)	(300,437)
Deposit in escrow	(542,099)	(202,942)	0
Net cash used for investing activities	(775,065)	(380,136)	(347,678)
Financing Activities
Proceeds from debt	1,875,000	787,400	563,400
Payments of debt	(1,102,748)	(612,680)	(493,819)
Stock re-purchase	(212,176)	(387,787)	(26,757)
Proceeds from exercise of stock options and other benefit plans	1,983	3,097	3,337
Excess income tax benefits from exercise of stock options	1,223	2,584	3,020
Payment of income tax withholding on share-based compensation	(6,658)	(14,565)	0
Earn-out settlement	0	0	(4,429)
Cash dividends ($0.28, $0.20, and $0.13 per share for the years ended December 31, 2015, 2014 and 2013	(32,430)	(26,963)	(19,246)
Net cash provided by (used for) financing activities	524,194	(248,914)	25,506
Effect of changes in currency exchange rates	(26,143)	(18,868)	(10,124)
Increase (decrease) in cash	172,293	(199,658)	140,089
Cash, beginning of year	226,191	425,849	285,760
Cash, end of year	$ 398,484	$ 226,191	$ 425,849