Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 32,086	$ 20,581	$ 36,314
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,871	17,786	14,525
Stock-based compensation expense	13,742	12,720	12,529
Provision (benefit) for deferred income taxes	(16,020)	(6,528)	3,363
Restructuring charges	36,599	1,284	1,390
Net (gain) loss on disposal of assets	1,197	286	1,629
Changes in operating assets and liabilities:
Accounts receivable	(31,863)	49,577	(12,135)
Inventories	(12,006)	(375)	(3,465)
Other current assets	10,345	5,294	1,689
Accounts payable	(3,259)	(2,710)	(10,813)
Other current liabilities and accrued expenses	(352)	(961)	3,124
Income taxes	(14,024)	13,823	(8,087)
Non-current assets	0	0	(1,968)
Net cash provided by operating activities	35,316	110,777	38,095
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(19,034)	(29,580)	(31,598)
Proceeds from sale of marketable securities	33,093	28,399	15,761
Payments to Acquire Businesses, Net of Cash Acquired	(75,374)	(15,313)	0
Proceeds from the sale of assets	0	2,200	0
Purchase of property and equipment	(9,611)	(10,233)	(18,887)
Net cash used in investing activities	(70,926)	(24,527)	(34,724)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Lines of Credit	1,103	0	0
Payments of Debt Issuance Costs	0	(562)	0
Purchase and retirement of treasury stock	0	(57,117)	(17,895)
Proceeds from exercise of stock options	26,337	3,723	1,981
Excess tax from stock-based compensation deduction	(1,046)	(811)	(1,011)
Proceeds from (Payments for) Other Financing Activities	(81)	(97)	(167)
Net cash provided by (used in) financing activities	26,313	(54,864)	(17,092)
EFFECT OF CURRENCY TRANSLATION ON CASH	858	(2,461)	446
INCREASE IN CASH AND CASH EQUIVALENTS	(8,439)	28,925	(13,275)
CASH AND CASH EQUIVALENTS, beginning of period	146,564	117,639	130,914
CASH AND CASH EQUIVALENTS, end of period	138,125	146,564	117,639
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	70	17	74
Cash paid for income taxes	14,888	3,630	23,254
Cash received for refunds of income taxes	2,945	7,434	7,430
Cash held in banks outside the United States	$ 29,068	$ 36,185	$ 67,426