Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 20,581	$ 36,314	$ 71,192
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,786	14,525	10,736
Stock-based compensation expense	12,720	12,529	8,501
Provision (benefit) for deferred income taxes	(6,528)	3,363	5,284
Restructuring charges	7,473	7,348	0
Net gain on disposal of gas flow control business			(12,531)
Net (gain) loss on disposal of assets	286	1,629	0
Changes in operating assets and liabilities:
Accounts receivable	49,577	(12,135)	(62,136)
Inventories	(375)	(3,465)	(41,299)
Other current assets	5,294	1,689	(6,318)
Accounts payable	(2,710)	(10,813)	26,521
Other current liabilities and accrued expenses	(7,150)	(2,834)	27,163
Income taxes	13,823	(8,087)	(9,188)
Non-current assets	0	(1,968)	469
Increase Decrease In Non Current Liabilities	0	0	(50)
Net cash provided by operating activities	110,777	38,095	18,344
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(29,580)	(31,598)	(109,516)
Proceeds from sale of marketable securities	28,399	15,761	144,055
Proceeds from sale of business	0	0	43,260
Payments to Acquire Businesses, Net of Cash Acquired	(15,313)	0	(75,577)
Proceeds from the sale of assets	2,200	0	0
Purchase of property and equipment	(10,233)	(18,887)	(18,932)
Net cash used in investing activities	(24,527)	(34,724)	(16,710)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments on capital lease obligations	(95)	(167)	(209)
Payments of Debt Issuance Costs	(562)	0
Purchase and retirement of treasury stock	(57,118)	(17,895)	0
Proceeds from exercise of stock options	3,722	1,981	1,397
Excess tax from stock-based compensation deduction	(811)	(1,011)	188
Net cash provided by (used in) financing activities	(54,864)	(17,092)	1,376
EFFECT OF CURRENCY TRANSLATION ON CASH	(2,461)	446	(5,202)
INCREASE IN CASH AND CASH EQUIVALENTS	28,925	(13,275)	(2,192)
CASH AND CASH EQUIVALENTS, beginning of period	117,639	130,914	133,106
CASH AND CASH EQUIVALENTS, end of period	146,564	117,639	130,914
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	17	74	55
Cash paid for income taxes	3,630	23,254	25,182
Cash received for refunds of income taxes	7,434	7,430	1,687
Cash held in banks outside the United States	36,185	67,426	22,032
Stock Issued During Period, Value, Acquisitions	$ 0	$ 0	$ 14,690