Basis of Financial Statement Preparation (Policies)	6 Months Ended
Basis of Financial Statement Preparation (Policies)	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of financial statement preparation, policy [Policy Text Block]	The condensed consolidated financial statements present the financial position, results of operations and cash flows of The Davey Tree Expert Company and its subsidiaries. When we refer to “we,” “us,” “our,” “Davey,” or “Davey Tree”, we mean The Davey Tree Expert Company and its subsidiaries, unless otherwise expressly stated or the context indicates otherwise. We have prepared the accompanying unaudited condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), as codified in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”), and with the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial information. The consolidated financial statements include all adjustments which, in the opinion of management, are necessary for a fair presentation of the results for the interim periods presented. All such adjustments are of a normal, recurring nature. All significant intercompany accounts and transactions have been eliminated. Certain information and disclosures required by U.S. GAAP for complete financial statements have been omitted in accordance with the rules and regulations of the SEC. We suggest that these condensed consolidated financial statements be read in conjunction with the financial statements included in our annual report on Form 10-K for the year ended December 31, 2017 (the “2017 Annual Report”).
Use of estimates, policy [Policy Text Block]	Use of Estimates in Financial Statement Preparation--The preparation of financial statements in accordance with U.S. GAAP requires the use of estimates and assumptions that affect reported amounts. Our consolidated financial statements include amounts that are based on management’s best estimates and judgments. Estimates are used for, but not limited to, accounts receivable valuation, depreciable lives of fixed assets, self-insurance accruals, income taxes and revenue recognition. Actual results could differ from those estimates.
Income tax, policy [Policy Text Block]	Our income tax provision for interim periods is determined using an estimate of our annual effective tax rate adjusted for discrete items, if any, that are taken into account in the relevant period. Each quarter we update our estimate of the annual effective tax rate and, if our estimated annual tax rate changes, we make a cumulative adjustment.
Earnings per share, policy [Policy Text Block]	We calculate our basic earnings per share by dividing net income or net loss by the weighted average number of common shares outstanding during the period. Diluted earnings per share are calculated in a similar manner, but include the effect of dilutive securities. To the extent these securities are antidilutive, they are excluded from the calculation of earnings per share.
Segment reporting, policy [Policy Text Block]	Measurement of Segment Profit and Loss and Segment Assets--We evaluate performance and allocate resources based primarily on operating income and also actively manage business unit operating assets. Segment information, including reconciling adjustments, is presented consistent with the basis described in our 2017 Annual Report.

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.