CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2022	Dec. 26, 2021	Dec. 27, 2020
Operating activities:
Net income (loss)	$ (33.2)	$ (1.6)	$ 79.4
Income (loss) from discontinued operations	0.9	(2.1)	(0.9)
Income (loss) from continuing operations	(34.1)	0.5	80.3
Adjustments to reconcile income (loss) from continuing operations to net cash provided by (used in) operating activities from continuing operations:
Depreciation and amortization	30.5	25.7	24.6
Deferred income taxes	(3.1)	(0.4)	(78.2)
Amortization of lease right-of-use assets	10.4	9.0	9.4
Stock-based compensation	26.3	25.8	21.0
Loss on extinguishment of debt	13.0	0.0	0.0
Amortization of deferred financing costs	0.8	1.0	1.0
Recovery of doubtful accounts	0.0	(0.2)	0.0
Litigation settlement charges	5.5	0.0	0.0
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	(4.9)	2.6	(3.7)
Unbilled receivables	(22.4)	(15.7)	3.6
Inventoried costs	(23.8)	(5.3)	(5.3)
Prepaid expenses	(1.9)	2.4	(2.1)
Other assets	(18.7)	(6.9)	(8.7)
Operating lease liabilities	(10.5)	(9.3)	(10.2)
Accounts payable	4.5	(5.3)	(2.4)
Accrued expenses	5.6	(7.4)	1.0
Accrued compensation	0.8	(1.3)	8.5
Accrued interest	0.1	(0.1)	(0.1)
Billings in excess of costs and earnings on uncompleted contracts	2.7	24.1	(5.0)
Income tax receivable and payable	0.1	1.4	(1.1)
Other liabilities	(6.5)	(5.3)	12.1
Net cash provided by (used in) operating activities from continuing operations	(25.6)	35.3	44.7
Investing activities:
Cash paid for acquisitions, net of cash acquired	(132.2)	(12.3)	(51.5)
Proceeds from sale of assets	0.2	2.2	0.1
Proceeds from insurance	0.0	4.5	0.0
Capital expenditures	(45.4)	(46.5)	(35.9)
Net cash used in investing activities from continuing operations	(177.4)	(52.1)	(87.3)
Financing activities:
Proceeds from the issuance of long-term debt	200.0	0.0	5.1
Proceeds from the issuance of common stock	0.0	0.0	240.4
Borrowing under credit facility	100.0	0.0	0.0
Redemption of Senior Secured Notes	(309.8)	0.0	0.0
Repayment under credit facility, term loan and other debt	(42.5)	(5.1)	(0.6)
Payments of employee taxes withheld from share-based awards	(12.5)	(9.1)	(1.4)
Debt issuance costs	(3.3)	0.0	0.0
Payments under finance leases	(1.4)	(1.0)	(0.6)
Proceeds from shares issued under equity plans	6.2	5.9	4.8
Net cash provided (used in) by financing activities from continuing operations	(63.3)	(9.3)	247.7
Net cash flows provided by (used in) continuing operations	(266.3)	(26.1)	205.1
Net operating cash flows of discontinued operations	(0.1)	(4.5)	1.9
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1.7)	(1.5)	1.9
Net increase (decrease) in cash, cash equivalents and restricted cash	(268.1)	(32.1)	208.9
Cash, cash equivalents and restricted cash at beginning of year	349.4	381.5	172.6
Cash, cash equivalents and restricted cash at end of year	81.3	349.4	381.5
Supplemental disclosure of cash flow information:
Cash paid during the year for interest	13.7	19.9	19.9
Net cash paid during the year for income taxes	4.4	2.0	2.5
Non-cash financing and investing activities:
Financing lease obligation incurred	9.1	5.8	0.9
Capital expenditures included in accounts payable and accrued expenses	2.7	3.0	2.9
Common stock issuance for purchase of noncontrolling interests	2.7	0.0	0.0
Common stock issuance for acquisition	$ 5.0	$ 0.0	$ 5.0