CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 25, 2022	Dec. 26, 2021
Operating activities:
Net income (loss)	$ 2.4	$ (33.2)	$ (1.6)
Income (loss) from discontinued operations	0.2	0.9	(2.1)
Income (loss) from continuing operations	2.2	(34.1)	0.5
Adjustments to reconcile income (loss) from continuing operations to net cash provided by (used in) operating activities from continuing operations:
Depreciation and amortization	33.2	30.5	25.7
Deferred income taxes	2.5	(3.1)	(0.4)
Amortization of lease right-of-use assets	11.5	10.4	9.0
Stock-based compensation	25.3	26.3	25.8
Loss on extinguishment of debt	0.0	13.0	0.0
Amortization of deferred financing costs	0.7	0.8	1.0
Provision (recovery) of doubtful accounts	1.0	0.0	(0.2)
Litigation settlement charges	0.0	5.5	0.0
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	(13.1)	(4.9)	2.6
Unbilled receivables	14.4	(22.4)	(15.7)
Inventoried costs	(29.6)	(23.8)	(5.3)
Prepaid expenses	(3.9)	(1.9)	2.4
Other assets	(12.3)	(18.7)	(6.9)
Operating lease liabilities	(11.4)	(10.5)	(9.3)
Accounts payable	4.4	4.5	(5.3)
Accrued expenses	1.4	5.6	(7.4)
Accrued compensation	12.4	0.8	(1.3)
Accrued interest	0.2	0.1	(0.1)
Billings in excess of costs and earnings on uncompleted contracts	28.4	2.7	24.1
Income tax receivable and payable	(0.5)	0.1	1.4
Other liabilities	(1.6)	(6.5)	(5.3)
Net cash provided by (used in) operating activities from continuing operations	65.2	(25.6)	35.3
Investing activities:
Cash paid for acquisitions, net of cash acquired	0.3	(132.2)	(12.3)
Proceeds from sale of assets	8.3	0.2	2.2
Proceeds from insurance	0.0	0.0	4.5
Capital expenditures	(52.4)	(45.4)	(46.5)
Net cash used in investing activities from continuing operations	(43.8)	(177.4)	(52.1)
Financing activities:
Proceeds from the issuance of long-term debt	0.0	200.0	0.0
Borrowing under credit facility	69.0	100.0	0.0
Redemption of Senior Secured Notes	0.0	(309.8)	0.0
Repayment under credit facility, term loan and other debt	(101.0)	(42.5)	(5.1)
Payments of employee taxes withheld from share-based awards	(3.7)	(12.5)	(9.1)
Debt issuance costs	0.0	(3.3)	0.0
Payments under finance leases	(1.5)	(1.4)	(1.0)
Proceeds from shares issued under equity plans	6.5	6.2	5.9
Net cash used in financing activities from continuing operations	(30.7)	(63.3)	(9.3)
Net cash used in continuing operations	(9.3)	(266.3)	(26.1)
Net operating cash flows of discontinued operations	0.0	(0.1)	(4.5)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.8	(1.7)	(1.5)
Net decrease in cash, cash equivalents and restricted cash	(8.5)	(268.1)	(32.1)
Cash, cash equivalents and restricted cash at beginning of year	81.3	349.4	381.5
Cash, cash equivalents and restricted cash at end of year	72.8	81.3	349.4
Supplemental disclosure of cash flow information:
Cash paid during the year for interest	19.6	13.7	19.9
Net cash paid during the year for income taxes	6.5	4.4	2.0
Non-cash financing and investing activities:
Financing lease obligation incurred	6.9	9.1	5.8
Capital expenditures included in accounts payable and accrued expenses	0.6	2.7	3.0
Common stock issuance for purchase of noncontrolling interests	10.7	2.7	0.0
Common stock issuance for acquisition	$ 14.8	$ 5.0	$ 0.0