Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017
Cash flows from operating activities:
Net income	$ 29,888	$ 13,254
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	6,131	6,107
Amortization	3,318	3,159
Provision for allowance for doubtful accounts	412	106
Stock-based compensation	1,198	1,037
Amortization of deferred financing costs and debt discount	1,165	1,401
Debt extinguishment costs	3,079
Gains on transfers and disposals of assets	(2,609)	(57)
Change in operating assets and liabilities:
Accounts receivable	(16,826)	(16,647)
Inventories	(3,152)	(4,544)
Contract assets, net, prepaid expenses, other current and other assets	(2,092)	268
Accounts payable, accrued and other liabilities	19,362	12,933
Net cash provided by operating activities	39,874	17,017
Cash flows from investing activities:
Purchases of property, plant and equipment	(14,892)	(6,324)
Proceeds from transfers and disposals of assets	5,820	57
Net cash used in investing activities	(9,072)	(6,267)
Cash flows from financing activities:
Payments of long-term debt	(146)
Payments of financing costs	(1,687)
Taxes paid relating to shares withheld on employee equity awards	(637)	(181)
Proceeds from exercise of stock options	1,561	502
Proceeds from issuance of common stock under employee stock purchase plan	11	17
Other	(10)	(16)
Net cash (used in) provided by financing activities	(908)	322
Net increase in cash and cash equivalents	29,894	11,072
Cash and cash equivalents at beginning of period	34,029	39,210
Cash and cash equivalents at end of period	$ 63,923	$ 50,282