Significant Accounting Principles and Policies - Impact of Restatement on Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2021	Mar. 29, 2020
Operating activities
Net income	$ 12,273	$ 26,150
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of property and equipment	2,268	2,583
Amortization of intangible assets	12,215	8,047
Amortization of debt issuance cost	777	6,063
Stock-based compensation	2,270	0
Net undistributed (loss) income from unconsolidated ventures	(2,411)	(663)
Deferred income taxes, net	2,818	(9,896)
Change in fair value of warrant liability	(1,200)	(33,599)
Other non-cash activities, net	(140)	270
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	22,685	20,869
Accounts payable	25,037	(2,417)
Accrued expenses	7,335	(292)
Customer advances and billings in excess of costs	(32,276)	18,223
Salaries, benefits and payroll taxes	13,951	(21,307)
Inventories, net		1,342
Prepaid expenses and other current assets		(2,921)
Other current and noncurrent liabilities	(10,632)	(4,545)
Investments	1,374	750
Other noncurrent assets	7,999	4,729
Accrued taxes	(392)	(2,473)
Net cash provided by operating activities	55,396	10,913
Investing activities
Expenditures for property and equipment	(2,434)	(404)
Proceeds from sales of property	222	0
Acquisition of noncontrolling interest	(14,300)	0
Other investing activities, net	(372)	0
Net cash used in investing activities	(16,884)	(404)
Financing activities
Net contributions from noncontrolling interests	490	150
Borrowings on long-term debt	20,000	60,000
Repayments on long-term debt	(20,000)	(196,544)
Payment of debt issuance costs	0	(964)
Recapitalization from merger with Gores III	0	605,708
Payment of underwriting and transaction costs	0	(27,268)
Distribution to selling stockholders	0	(419,548)
Stock-based compensation tax withholding obligation	(5,659)	0
Net cash (used in) provided by financing activities	(5,169)	21,534
Effect of exchange rate changes on cash and cash equivalents	(1,101)	(288)
Net increase in cash and cash equivalents	32,242	31,755
Cash and cash equivalents at beginning of period	85,908	68,035
Cash and cash equivalents at end of period	118,150	99,790
Supplemental cash flow information
Cash paid for interest	11,977	10,900
Cash paid for taxes	$ 471	1,523
As filed
Operating activities
Net income		(4,777)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of property and equipment		2,583
Amortization of intangible assets		8,047
Amortization of debt issuance cost		6,063
Net undistributed (loss) income from unconsolidated ventures		(663)
Deferred income taxes, net		(9,081)
Change in fair value of warrant liability		0
Other non-cash activities, net		270
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net		20,869
Accounts payable		(2,417)
Accrued expenses		(3,779)
Customer advances and billings in excess of costs		18,223
Salaries, benefits and payroll taxes		(21,307)
Inventories, net		1,342
Prepaid expenses and other current assets		(2,921)
Other current and noncurrent liabilities		(4,545)
Investments		750
Other noncurrent assets		4,729
Accrued taxes		(2,473)
Net cash provided by operating activities		10,913
Investing activities
Expenditures for property and equipment		(404)
Net cash used in investing activities		(404)
Financing activities
Net contributions from noncontrolling interests		150
Borrowings on long-term debt		60,000
Repayments on long-term debt		(196,544)
Payment of debt issuance costs		(964)
Recapitalization from merger with Gores III		605,708
Payment of underwriting and transaction costs		(27,268)
Distribution to selling stockholders		(419,548)
Net cash (used in) provided by financing activities		21,534
Effect of exchange rate changes on cash and cash equivalents		(288)
Net increase in cash and cash equivalents		31,755
Cash and cash equivalents at beginning of period		68,035
Cash and cash equivalents at end of period		99,790
Supplemental cash flow information
Cash paid for interest		10,900
Cash paid for taxes		1,523
Restatement adjustments
Operating activities
Net income		30,927
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of property and equipment		0
Amortization of intangible assets		0
Amortization of debt issuance cost		0
Net undistributed (loss) income from unconsolidated ventures		0
Deferred income taxes, net		(815)
Change in fair value of warrant liability		(33,599)
Other non-cash activities, net		0
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net		0
Accounts payable		0
Accrued expenses		3,487
Customer advances and billings in excess of costs		0
Salaries, benefits and payroll taxes		0
Inventories, net		0
Prepaid expenses and other current assets		0
Other current and noncurrent liabilities		0
Investments		0
Other noncurrent assets		0
Accrued taxes		0
Net cash provided by operating activities		0
Investing activities
Expenditures for property and equipment		0
Net cash used in investing activities		0
Financing activities
Net contributions from noncontrolling interests		0
Borrowings on long-term debt		0
Repayments on long-term debt		0
Payment of debt issuance costs		0
Recapitalization from merger with Gores III		0
Payment of underwriting and transaction costs		0
Distribution to selling stockholders		0
Net cash (used in) provided by financing activities		0
Effect of exchange rate changes on cash and cash equivalents		0
Net increase in cash and cash equivalents		0
Cash and cash equivalents at beginning of period		0
Cash and cash equivalents at end of period		0
Supplemental cash flow information
Cash paid for interest		0
Cash paid for taxes		$ 0