Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016
Cash flows provided by operating activities:
Net income	$ 68,519	$ 65,183
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	38,372	37,305
Impairment of assets	1,505	37
Loss on disposal of property, plant and equipment	571	553
Bad debt expense (recovery)	170	(170)
Stock-based compensation expense	4,593	8,122
Excess tax benefit from stock-based compensation arrangements	0	(12,387)
Deferred income taxes	(3,581)	5,464
Changes in operating assets and liabilities:
Accounts receivable	(6,658)	(7,037)
Inventories	(9,330)	(2,897)
Prepaid expenses, income tax receivable and other assets	2,852	11,841
Accounts payable	5,371	(4,571)
Accrued expenses and other current liabilities	6,244	13,365
Other liabilities	(390)	(6,446)
Net cash provided by operating activities	108,238	108,362
Cash flows used in investing activities:
Purchases of property, plant and equipment	(23,415)	(37,108)
Proceeds from disposal of property, plant and equipment	16	4
Change in restricted cash	(4)	62
Net cash used in investing activities	(23,403)	(37,042)
Cash flows used in financing activities:
Repurchase of Class A Common Stock	(121,535)	(138,055)
Proceeds from exercise of stock options	15,159	37,452
Payment of taxes related to exercise of stock options	0	(510)
Cash paid on note payable	(60)	(58)
Excess tax benefit from stock-based compensation arrangements	0	12,387
Net proceeds from sale of investment shares	611	537
Net cash used in financing activities	(105,825)	(88,247)
Change in cash and cash equivalents	(20,990)	(16,927)
Cash and cash equivalents at beginning of year	91,035	94,193
Cash and cash equivalents at end of period	70,045	77,266
Supplemental disclosure of cash flow information:
Income taxes paid	22,408	21,939
Income taxes refunded	2	12,002
(Decrease) Increase in accounts payable for purchase of property, plant and equipment	(3,763)	1,235
Decrease in accounts payable for repurchase of Class A Common Stock	$ 0	$ (3,000)