Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Cash flows provided by (used in) operating activities:
Net income	$ 23,694	$ 9,310
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,863	12,820
Loss on disposal of property, plant and equipment	271	143
Lease expense	859
Bad debt expense		47
Stock-based compensation expense	2,066	1,491
Deferred income taxes	1,029	178
Changes in operating assets and liabilities:
Accounts receivable	(20,452)	(16,615)
Inventories	(15,353)	(8,166)
Prepaid expenses, income tax receivable and other assets	1,336	(4,689)
Accounts payable	14,400	2,299
Accrued expenses and other current liabilities	(6,465)	(6,575)
Net lease liabilities	(624)
Other liabilities	19	(658)
Net cash provided by (used in) operating activities	13,643	(10,415)
Cash flows used in investing activities:
Purchases of property, plant and equipment	(22,080)	(11,477)
Proceeds from disposal of property, plant and equipment	1	2
Change in restricted cash	28	111
Net cash used in investing activities	(22,051)	(11,364)
Cash flows provided by financing activities:
Repurchase of Class A Common Stock		(16,640)
Proceeds from exercise of stock options	2,768	19,304
Cash paid on note payable	(72)	(63)
Net proceeds from sale of investment shares	200	186
Net cash provided by financing activities	2,896	2,787
Change in cash and cash equivalents	(5,512)	(18,992)
Cash and cash equivalents at beginning of year	108,399	65,637
Cash and cash equivalents at end of period	102,887	46,645
Supplemental disclosure of cash flow information:
Income taxes paid	207	459
Cash paid for amounts included in measurement of lease liabilities	901
Right-of-use assets obtained in exchange for lease obligations	27,037
Decrease in accounts receivable for ASU 2014-09 adoption		(1,310)
Increase in accounts payable for purchase of property, plant and equipment	$ 118	$ 2,741