Acquisitions - Narrative (Details) - USD ($)			3 Months Ended	12 Months Ended
	Jan. 02, 2019	Sep. 05, 2017	Apr. 01, 2018	Dec. 29, 2019	Dec. 30, 2018
Business Acquisition [Line Items]
Additions to Goodwill				$ 20,500,000
NextGen Global Resources LLC
Business Acquisition [Line Items]
Ownership percentage acquired (percent)	100.00%
Purchase price of acquisition	$ 51,000,000.0
Purchase price paid at closing	54,300,000
Intangible assets acquired	$ 21,500,000
Pro forma information, revenue of acquiree since acquisition date, actual				78,300,000
Pro forma information, earnings or loss of acquiree since acquisition date, actual				4,500,000
Business combination, revenue reported by acquired entity for prior period					$ 67,800,000
Business combination, net earnings reported by acquired entity for prior period					3,000,000.0
Global Technology Associates, LLC
Business Acquisition [Line Items]
Ownership percentage acquired (percent)	100.00%
Purchase price of acquisition	$ 34,000,000.0
Purchase price paid at closing	35,700,000
Intangible assets acquired	17,300,000
Pro forma information, revenue of acquiree since acquisition date, actual				62,800,000
Pro forma information, earnings or loss of acquiree since acquisition date, actual				4,500,000
Business combination, revenue reported by acquired entity for prior period					42,500,000
Business combination, net earnings reported by acquired entity for prior period					3,300,000
Teachers On Call, Inc.
Business Acquisition [Line Items]
Ownership percentage acquired (percent)		100.00%
Purchase price of acquisition		$ 41,000,000.0
Purchase price paid at closing		39,000,000.0
Intangible assets acquired		18,300,000
Additions to Goodwill			$ 200,000
Goodwill expected to be deductible				18,800,000
Indemnification asset recognized as of the acquisition date		$ 2,800,000
Indemnification asset				$ 0	$ 100,000
Customer Relationships | NextGen Global Resources LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 12,900,000
Acquired finite-lived intangible assets, weighted average useful life (years)	10 years
Customer Relationships | Global Technology Associates, LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 12,100,000
Acquired finite-lived intangible assets, weighted average useful life (years)	10 years
Trade Names | NextGen Global Resources LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 8,100,000
Acquired finite-lived intangible assets, weighted average useful life (years)	15 years
Trade Names | Global Technology Associates, LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 4,000,000.0
Acquired finite-lived intangible assets, weighted average useful life (years)	15 years
Noncompete Agreements | NextGen Global Resources LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 500,000
Acquired finite-lived intangible assets, weighted average useful life (years)	5 years
Noncompete Agreements | Global Technology Associates, LLC
Business Acquisition [Line Items]
Intangible assets acquired	$ 1,200,000
Acquired finite-lived intangible assets, weighted average useful life (years)	5 years