Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Cash Flows from Operating Activities:
Net income	$ 30,647	$ 29,187
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, amortization and accretion	6,378	5,005
Provision for doubtful accounts		75
Provision (benefit) for deferred income taxes	1,110	(1,186)
Provision for non-cash stock compensation	851	653
Changes in assets and liabilities:
Accounts receivable	(8,880)	(2,473)
Inventories	6,309	(818)
Prepaids and other current assets	(1,550)	144
Other assets	(1,075)	(191)
Accounts payable	(16,519)	(668)
Accrued compensation and other liabilities	2,480	8,417
Cash provided by operating activities	19,751	38,145
Cash Flows from Investing Activities:
Property, plant and equipment additions	(6,276)	(5,618)
Purchase of investments		(13,127)
Cash used in investing activities	(6,276)	(18,745)
Cash Flows from Financing Activities:
Other stock related activity	(563)	(856)
Purchase and cancellation of common stock	(9,208)	(11,321)
Cash used in financing activities	(9,771)	(12,177)
Effect of exchange rate changes on Cash and Cash Equivalents	(51)
Net Increase in Cash and Cash Equivalents	3,653	7,223
Cash and Cash Equivalents, Beginning of Period	71,691	149,121
Cash and Cash Equivalents, End of Period	75,344	156,344
Supplemental Cash Flow Information
Cash paid for interest expense	66	61
Cash paid for income taxes	$ 295	$ 1,046