CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2021	Sep. 27, 2020
Cash flows from operating activities:
Net income (loss)	$ 41,424	$ (149,867)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	20,405	24,002
Goodwill and intangible asset impairment charge	0	175,189
Provision for credit losses	2,881	6,582
Stock-based compensation	10,149	6,762
Deferred income taxes	445	(25,955)
Non-cash lease expense	11,173	11,115
Other operating activities	(1,484)	1,944
Changes in operating assets and liabilities:
Accounts receivable	(53,626)	55,408
Income tax receivable	963	(4,928)
Operating lease right-of-use asset	7,150	0
Other assets	(7,003)	(2,646)
Accounts payable and other accrued expenses	3,212	(12,723)
Other accrued wages and benefits	24,278	(7,395)
Deferred employer payroll taxes	(57,066)	36,312
Workers’ compensation claims reserve	3,075	(824)
Operating lease liabilities	(10,017)	(11,410)
Other liabilities	4,598	(2,798)
Net cash provided by operating activities	557	98,768
Cash flows from investing activities:
Capital expenditures	(28,772)	(16,244)
Purchases of restricted available-for-sale investments	(29)	(2,310)
Sales of restricted available-for-sale investments	793	3,212
Purchases of restricted held-to-maturity investments	0	(32,495)
Maturities of restricted held-to-maturity investments	18,346	24,358
Net cash used in investing activities	(9,662)	(23,479)
Cash flows from financing activities:
Purchases and retirement of common stock	0	(52,346)
Net proceeds from employee stock purchase plans	754	734
Common stock repurchases for taxes upon vesting of restricted stock	(3,035)	(2,331)
Net change in revolving credit facility	0	(35,600)
Other	(270)	(1,436)
Net cash used in financing activities	(2,551)	(90,979)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(613)	(466)
Net change in cash, cash equivalents and restricted cash	(12,269)	(16,156)
Cash, cash equivalents and restricted cash, beginning of period	118,612	92,371
Cash, cash equivalents and restricted cash, end of period	106,343	76,215
Supplemental Disclosure of Cash Flow Information [Abstract]
Interest	1,174	2,672
Income taxes	5,522	(3,414)
Operating lease liabilities	12,402	13,147
Property and equipment purchased but not yet paid	2,394	1,614
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 10,739	$ 8,672