CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 8,839,000	$ 6,730,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,976,000	2,314,000
Deferred income taxes, net	1,784,000	2,556,000
Loss on sale/disposal of equipment	26,000	3,000
(Recovery of) provision for doubtful accounts	(98,000)	92,000
Stock-based compensation	1,992,000	732,000
Accretion and fair value adjustments of contingent consideration	779,000	(139,000)
Changes in operating assets and liabilities, net of effects from business acquisitions:
Accounts receivable	(5,061,000)	5,148,000
Costs and estimated earnings in excess of billings on uncompleted contracts	(8,200,000)	(7,956,000)
Other receivables	(1,071,000)	(1,918,000)
Prepaid expenses and other current assets	(167,000)	(335,000)
Other assets	44,000	56,000
Accounts payable	5,408,000	1,760,000
Accrued liabilities	(3,340,000)	5,246,000
Billings in excess of costs and estimated earnings on uncompleted contracts	(1,812,000)	2,469,000
Deferred lease obligations	(64,000)	(9,000)
Net cash provided by operating activities	2,035,000	16,749,000
Cash flows from investing activities:
Purchase of equipment and leasehold improvements	(1,826,000)	(1,386,000)
Cash paid for acquisitions, net of cash acquired	(14,603,000)	(8,857,000)
Net cash used in investing activities	(16,429,000)	(10,243,000)
Cash flows from financing activities:
Payments on contingent consideration	(1,659,000)	(1,285,000)
Payments on notes payable	(3,270,000)	(3,083,000)
Principal payments on capital lease obligations	(323,000)	(411,000)
Proceeds from stock option exercise	1,751,000	164,000
Proceeds from sales of common stock under employee stock purchase plan	830,000	209,000
Net cash used in financing activities	(2,671,000)	(4,406,000)
Net (decrease) increase in cash and cash equivalents	(17,065,000)	2,100,000
Cash and cash equivalents at beginning of period	22,668,000	16,487,000
Cash and cash equivalents at end of period	5,603,000	18,587,000
Cash paid during the period for:
Interest	88,000	137,000
Income taxes	2,142,000	2,046,000
Supplemental disclosures of noncash investing and financing activities:
Issuance of notes payable related to business acquisitions		4,569,000
Issuance of common stock related to business acquisitions	3,099,000	2,228,000
Contingent consideration related to business acquisitions	5,400,000
Other payable for working capital adjustment	1,881,000
Other receivable for working capital adjustment		604,000
Equipment acquired under capital leases	$ 263,000	$ 186,000