The Davey 401KSOP and Employee Stock Ownership Plan (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2019	Dec. 31, 2018
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Employee Stock Ownership Plan (ESOP), Initial Shares in ESOP	120,000
Employee Stock Ownership Plan (ESOP), Shares Adjusted for Stock Split	23,040,000
Employee Stock Ownership Plan (ESOP), Initial Value in ESOP	$ 2,700
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	3.00%
Defined Contribution Plan, Eligible Age	21 years
Defined Contribution Plan, Service Requirement for Eligibility	1 year
Number of put option periods	2
Duration of put option periods	60 days
Employee Stock Ownership Plan (ESOP), Fair Value of Shares Subject to Repurchase Obligation	$ 3,992	$ 6,288
Company shares held in 401KSOP shares, fair value	115,766	112,761
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP); 5,299 and 5,642 shares at redemption value as of September 28, 2019 and December 31, 2018	$ 119,758	$ 119,049
Defined Contribution Plan, Tier 1 [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	100.00%
Defined Contribution Plan, Tier 2 [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	50.00%
Maximum [Member] | Defined Contribution Plan, Tier 1 [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	1.00%
Maximum [Member] | Defined Contribution Plan, Tier 2 [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%