CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH PROVIDED BY OPERATING ACTIVITIES:
Net earnings	$ 200,261us-gaap_NetIncomeLoss	$ 177,015us-gaap_NetIncomeLoss	$ 222,398us-gaap_NetIncomeLoss
Income items not affecting cash:
Depreciation and amortization	57,245us-gaap_DepreciationAndAmortization	62,796us-gaap_DepreciationAndAmortization	59,715us-gaap_DepreciationAndAmortization
Deferred income taxes	(1,242)us-gaap_DeferredIncomeTaxExpenseBenefit	(2,709)us-gaap_DeferredIncomeTaxExpenseBenefit	(10,940)us-gaap_DeferredIncomeTaxExpenseBenefit
Stock-based compensation arrangements	30,788us-gaap_ShareBasedCompensation	27,823us-gaap_ShareBasedCompensation	26,250us-gaap_ShareBasedCompensation
Gain on sale of certain optics assets	(4,129)us-gaap_GainLossOnDispositionOfAssets1	0us-gaap_GainLossOnDispositionOfAssets1	0us-gaap_GainLossOnDispositionOfAssets1
Other non-cash items	(791)us-gaap_OtherNoncashIncomeExpense	4,564us-gaap_OtherNoncashIncomeExpense	(1,810)us-gaap_OtherNoncashIncomeExpense
Changes in operating assets and liabilities, net of acquisitions:
(Increase) decrease in accounts receivable,net	(76,705)	48,640	10,693
Decrease (increase) in inventories	11,363us-gaap_IncreaseDecreaseInInventories	35,181us-gaap_IncreaseDecreaseInInventories	(23,733)us-gaap_IncreaseDecreaseInInventories
Decrease (increase) in prepaid expenses and other current assets	5,754	5,434	(1,004)
(Increase) decrease in other assets	(24,261)	(1,520)	1,879
Increase) decrease in accounts payable	15,040	(8,617)	(1,672)
Increase (decrease) in deferred revenue	93	(659)	1,153
Increase (decrease) in accrued payroll and other liabilities	17,240	36,017	(25,415)
(Decrease) increase in accrued income taxes	(8,501)	(18,898)	20,141
Increase (decrease) in pension and other long-term liabilities	4,089	(10,102)	7,890
Cash provided by operating activities	226,244	354,965	285,545
CASH USED BY INVESTING ACTIVITIES:
Additions to property and equipment	(61,262)	(52,061)	(58,089)
Business acquisitions, net of cash acquired	0	(20,073)	(105,909)
Proceeds from sale of certain optics assets	12,000	0	0
Other investments	0	0	(3,002)
Cash used by investing activities	(49,262)	(72,134)	(167,000)
CASH (USED) PROVIDED BY FINANCING ACTIVITIES:
Net proceeds of long-term debt, including current portion	0us-gaap_ProceedsFromRepaymentsOfDebt	150,000us-gaap_ProceedsFromRepaymentsOfDebt	0us-gaap_ProceedsFromRepaymentsOfDebt
Repayment of long-term debt	(15,000)us-gaap_RepaymentsOfLongTermDebt	(11,250)us-gaap_RepaymentsOfLongTermDebt	0us-gaap_RepaymentsOfLongTermDebt
Repurchase of common stock	(139,238)	(162,078)	(214,195)
Dividends paid	(56,513)us-gaap_PaymentsOfDividendsCommonStock	(51,404)us-gaap_PaymentsOfDividendsCommonStock
Proceeds from shares issued pursuant to stock-based compensation plans	47,581	8,650	11,198
Excess tax benefit of stock options exercised	11,161	1,069	1,284
Other financing activities	(18)	(1,100)	(166)
Cash (used) provided by financing activities	(152,027)	(66,113)	(244,329)
Effect of exchange rate changes on cash	(36,057)	4,019	6,677
Net decrease (increase) in cash and cash equivalents	(11,102)	220,737	(119,107)
Cash and cash equivalents, beginning of year	542,476	321,739	440,846
Cash and cash equivalents, end of year	$ 531,374	$ 542,476	$ 321,739

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.