Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 40,531	$ 35,127
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	8,102	7,217
Deferred income taxes	(2,610)	4,324
Stock-based compensation	3,267	2,532
Unrealized gains on foreign currency transactions	(1,355)	(481)
Other	422	(16)
Provisions for inventory, warranty & bad debt	5,284	3,705
Changes in assets and liabilities that provided (used) cash:
Accounts receivable	(4,373)	(8,250)
Inventories	(3,856)	(6,984)
Prepaid expenses and other current assets	(4,731)	(2,212)
Accounts payable	516	(1,936)
Accrued expenses and other liabilities	3,934	(2,658)
Income and other taxes payable	(175)	(40,243)
Tax benefit from exercise of employee stock options	(1,565)	(1,464)
Net cash provided by (used in) operating activities	43,391	(11,339)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(11,456)	(17,746)
Proceeds from sales of property, plant and equipment	119	89
Acquisition of businesses	0	(5,555)
Other	32	375
Net cash used in investing activities	(11,305)	(22,837)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from line-of-credit facilities	10,889	8,897
Payments on line-of-credit facilities	(11,861)	(1,415)
Principal payments on long-term borrowings	(333)	(1,640)
Exercise of employee stock options and issuances under employee stock purchase plan	611	720
Tax benefit from exercise of employee stock options	1,565	1,464
Net cash provided by financing activities	871	8,026
EFFECT OF CHANGES IN EXCHANGE RATES ON CASH AND CASH EQUIVALENTS	(1,124)	(2,188)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	31,833	(28,338)
CASH AND CASH EQUIVALENTS — Beginning of period	448,776	384,053
CASH AND CASH EQUIVALENTS — End of period	480,609	355,715
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	102	88
Cash paid for income taxes	20,893	47,813
Non-cash transactions:
Demonstration units transferred from inventory to other assets	610	625
Inventory transferred to machinery and equipment	717	0
Additions to property, plant and equipment included in accounts payable	$ 1,541	$ 1,115