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	$ 126,673	$ 114,920	$ 103,637
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	23,693	22,814	18,931
Amortization	10,568	5,852	2,054
Stock-based compensation	18,327	14,154	11,111
Asset impairments and write-offs of intangible assets	0	0	1,434
Other	27	9	3
Income taxes payable (receivable), net	13,066	(3,979)	6,908
Deferred income taxes	(6,743)	2,350	(5,175)
Decrease (increase), net of acquisitions, in:
Receivables	12,982	(22,077)	(5,389)
Inventories	1,486	(24,309)	(42,337)
Other assets	3,781	(2,949)	(11,072)
Increase (decrease), net of acquisitions, in:
Accounts payable	18,553	397	1,324
Accrued payroll liabilities	5,429	(12,685)	15,832
Accrued warranty reserves	660	176	3,077
Deferred revenue	13,285	(4,703)	(8,544)
Accrued restructuring, reorganization, relocation and severance	(2,628)	397	(2,860)
Other liabilities	(1,211)	(5,413)	13,784
Net cash provided by operating activities	237,948	84,954	102,718
Cash flows from investing activities:
(Increase) decrease in restricted cash	(7,894)	25,083	(5,059)
Acquisition of property, plant and equipment	(62,414)	(22,111)	(13,775)
Payments for acquisitions, net of cash acquired	(2,694)	(93,368)	(14,050)
Purchase of investments in marketable securities	(227,119)	(173,908)	(146,571)
Redemption of investments in marketable securities	180,332	134,478	159,520
Other	(2,710)	(10,874)	(992)
Net cash used in investing activities	(122,499)	(140,700)	(20,927)
Cash flows from financing activities:
Dividends paid on common stock	(16,191)	(6,095)	0
Redemption of 2.875% convertible note	(73)	0	0
Withholding taxes paid on issuance of vested restricted stock units	(9,658)	(5,913)	(3,789)
Proceeds from exercise of stock options and employee stock purchases	16,545	13,131	24,382
Excess tax benefit for share based payment arrangements	6,010	2,873	1,425
Repurchases of common stock	0	(891)	(50,000)
Other financing activities	0	(1,869)	(1,367)
Net cash (used in) provided by financing activities	(3,367)	1,236	(29,349)
Effect of exchange rate changes	5,786	451	(9,698)
Increase (decrease) in cash and cash equivalents	117,868	(54,059)	42,744
Cash and cash equivalents:
Beginning of period	266,302	320,361	277,617
End of period	384,170	266,302	320,361
Supplemental Cash Flow Information:
Cash paid for income taxes, net	10,917	23,802	9,391
Cash paid for interest	1,322	3,559	3,539
Increase in fixed assets related to transfers with inventories	11,091	21,239	9,034
Increase in goodwill from acquisition-related liabilities	0	0	3,456
Dividends declared but not paid	5,011	3,046	0
Conversion of 2.875% convertible notes	88,937	0	0
Accrued purchases of plant and equipment	$ 1,014	$ 1,120	$ 1,099