CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012
Cash flows from operating activities:
Net income	$ 60,263	$ 70,549
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,841	14,621
Fixed assets impairment	1,961
Investment premium amortization, net	2,557	1,628
Allowance for bad debt	(199)
Change in fair value of contingent consideration	3,913
Non-cash interest income (expense) and other	(151)	(1,623)
Tax benefit related to stock options	1,551	2,200
Share-based compensation expense	20,226	16,033
Excess tax benefits from share-based compensation	(1,750)	(2,212)
Loss on disposal of assets	70	57
Change in net deferred tax liability	(515)	(4,152)
Changes in assets and liabilities:
Receivables	3,957	(2,021)
Inventories	(20,578)	5,220
Other current and non-current assets	1,499	(4,525)
Accounts payable	(92)	2,668
Income taxes, net	(1,650)	1,708
Other current and non-current liabilities	1,548	9,052
Net cash provided by operating activities	86,451	109,203
Cash flows from investing activities:
Purchases of available-for-sale investments	(132,351)	(128,080)
Sales and maturities of available-for-sale investments	108,019	134,216
Acquisition of a business	(13,000)
Purchases of property, plant and equipment, net	(6,916)	(7,308)
Net cash used in investing activities	(44,248)	(1,172)
Cash flows from financing activities:
Payment of contingent consideration	(4,220)	(1,518)
Proceeds from stock option exercises	6,635	5,222
Proceeds from stock issued under employee stock purchase plan	2,536	1,896
Excess tax benefits from share-based compensation	1,750	2,212
Repurchase and retirement of common shares	(47,089)	(10,372)
Net cash used in financing activities	(40,388)	(2,560)
Effect of exchange rate changes on cash and cash equivalents	(294)	(94)
Net increase in cash and cash equivalents	1,521	105,377
Net cash and cash equivalents at beginning of period	101,322	42,661
Net cash and cash equivalents at end of period	102,843	148,038
Supplemental disclosure of consolidated cash flow information:
Cash paid for income taxes	21,237	31,589
Cash paid for interest	4	3
Supplemental disclosure of consolidated non-cash investing and financing activities:
Transfers of equipment from inventory	1,754	2,406
Purchases of property, plant and equipment through accounts payable and accrued liabilities	670	1,206
Acquisition of DuraHeart II:
Contingent consideration included in contingent liabilities, non-current portion	$ 18,800