Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012
Cash flows from operating activities:
Net income	$ 56,794	$ 55,960
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,451	10,473
Amortization	5,248	1,836
Stock-based compensation	8,712	6,676
Other	16	46
Income taxes payable, net	8,188	168
Deferred income taxes	(4,389)	(365)
Decrease (increase), net of acquisitions, in:
Receivables	8,517	(26,315)
Inventories	(5,171)	(24,418)
Other assets	1,348	(5,884)
Increase (decrease), net of acquisitions, in:
Accounts payable	6,356	9,900
Accrued payroll liabilities	(4,759)	(18,060)
Accrued warranty reserves	258	(255)
Deferred revenue	8,188	(381)
Accrued restructuring, reorganization, relocation and severance	(1,601)	(2,212)
Other liabilities	(7,628)	1,953
Net cash provided by operating activities	91,528	9,122
Cash flows from investing activities:
(Increase) decrease in restricted cash	(6,561)	30,199
Acquisition of property, plant and equipment	(42,566)	(11,633)
Payments for acquisitions, net of cash acquired	0	(30,171)
Purchase of investments in marketable securities	(73,397)	(66,434)
Redemption of investments in marketable securities	69,915	75,950
Other	(1,304)	(624)
Net cash used in investing activities	(53,913)	(2,713)
Cash flows from financing activities:
Conversion of 2.875% convertible notes	(73)	0
Dividends paid on common stock	(6,164)	0
Withholding taxes paid on issuance of vested restricted stock units	(439)	(1,465)
Proceeds from exercise of stock options and employee stock purchases	6,816	5,013
Excess tax benefit for share based payment arrangements	1,069	653
Repurchases of common stock	0	(890)
Net cash provided by financing activities	1,209	3,311
Effect of exchange rate changes	(1,056)	(5,836)
Increase in cash and cash equivalents	37,768	3,884
Cash and cash equivalents:
Beginning of period	266,302	320,361
End of period	304,070	324,245
Supplemental Cash Flow Information:
Cash paid for income taxes, net	6,204	20,088
Cash paid for interest	1,439	1,834
Increase in fixed assets related to transfers with inventories	5,873	11,629
Dividends declared but not paid	4,996	3,046
Conversion of 2.875% convertible notes	$ 88,937	$ 0
Convertible Subordinated Debt [Member]
Supplemental Cash Flow Information:
Convertible notes, stated interest rate	2.875%