Davey Tree Expert 10-K 16 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 09, 2018	Jul. 01, 2017
Document and Entity Information [Abstract]
Entity registrant name	DAVEY TREE EXPERT CO
Entity central index key	277,638
Current fiscal year end date	--12-31
Entity filer category	Accelerated Filer
Document type	10-K
Document period end date	Dec. 31, 2017
Document fiscal year focus	2,017
Document fiscal period focus	FY
Amendment flag	false
Entity common stock, shares outstanding		24,227,668
Entity well-known seasoned issuer	No
Entity voluntary filers	No
Entity current reporting status	Yes
Entity public float			$ 390,025,072

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash	$ 13,121	$ 9,006
Accounts receivable, net	168,671	146,134
Operating supplies	10,069	7,277
Prepaid expenses	15,893	14,493
Other current assets	1,371	1,863
Total current assets	209,125	178,773
Property and equipment:
Land and land improvements	18,215	16,263
Buildings and leasehold improvements	40,285	37,676
Equipment	557,536	534,711
Property and equipment	616,036	588,650
Less accumulated depreciation	422,853	409,214
Property and equipment, net	193,183	179,436
Other assets	29,156	31,354
Identified intangible assets and goodwill, net	41,671	34,376
Total assets	473,135	423,939
Current liabilities:
Short-term debt	16,315	16,701
Current portion of capital leases	651	170
Accounts payable	45,093	41,283
Accrued expenses	42,816	37,659
Self-insurance accruals	23,782	23,092
Total current liabilities	128,657	118,905
Long-term debt	105,469	72,194
Senior unsecured notes	11,882	17,923
Capital leases	1,859	2,173
Self-insurance accruals	43,912	39,746
Other liabilities	19,966	20,819
Total liabilities	311,745	271,760
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP): 6,467 and 7,057 shares at redemption value as of December 31, 2017 and 2016	123,520	124,201
Common shareholders' equity:
Common shares, $1.00 par value, per share; 48,000 shares authorized; 36,447 and 35,857 shares issued and outstanding before treasury shares and which excludes 6,467 and 7,057 shares subject to redemption as of December 31, 2017 and 2016	36,447	35,857
Additional paid-in capital	58,554	41,626
Common shares subscribed	7,529	8,209
Retained earnings	143,835	133,951
Accumulated other comprehensive loss	(8,393)	(12,162)
Stockholders' equity before treasury stock	237,972	207,481
Less: Cost of Common shares held in treasury; 18,693 shares in 2017 and 17,991 in 2016	198,327	176,530
Common shares subscription receivable	1,775	2,973
Common shareholders' equity	37,870	27,978
Total liabilities and shareholders' equity	$ 473,135	$ 423,939

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical)	12 Months Ended
	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016$ / sharesshares
Stock split, conversion ratio	2
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1
Common stock, shares authorized	48,000,000	48,000,000
Redeemable stock, outstanding	6,467,027	7,056,904
Common stock, shares issued	36,446,890	35,856,856
Common stock, shares outstanding	36,447,000	35,857,000
Treasury stock, shares	18,692,901	17,990,620

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues	$ 915,958	$ 845,678	$ 821,904
Costs and expenses:
Operating	587,333	541,486	528,899
Selling	167,934	152,106	144,234
General and administrative	64,589	61,789	59,798
Depreciation	50,702	47,284	44,677
Amortization of intangible assets	2,384	2,306	2,214
Gain on sale of assets, net	(3,989)	(4,664)	(2,026)
Costs and expenses	868,953	800,307	777,796
Income from operations	47,005	45,371	44,108
Other income (expense):
Interest expense	(4,886)	(4,393)	(3,355)
Interest income	292	255	249
Other	(4,417)	(3,989)	(5,744)
Income before income taxes	37,994	37,244	35,258
Income taxes	15,874	14,960	13,460
Net income	$ 22,120	$ 22,284	$ 21,798
Share data:
Earnings per share--basic	$ 0.87	$ 0.85	$ 0.81
Earnings per share--diluted	$ 0.83	$ 0.82	$ 0.78
Weighted-average shares outstanding:
Basic	25,557,468	26,212,040	26,930,898
Diluted	26,697,062	27,247,354	27,954,580
Dividends declared per share	$ 0.100	$ 0.100	$ 0.100

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2017
Income Statement [Abstract]
Stock split, conversion ratio	2

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 22,120	$ 22,284	$ 21,798
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments gains/(losses)	2,195	744	(5,093)
Defined benefit pension plans:
Net (loss)/gain arising during the year	(1,286)	(1,219)	326
Amortization of defined benefit pension items:
Net actuarial loss	2,822	1,912	2,863
Prior service cost	38	(205)	33
Amortization of defined benefit pension items:	2,860	1,707	2,896
Defined benefit pension plan adjustments	(1,574)	(488)	(3,222)
Total other comprehensive income (loss), net of tax	3,769	1,232	(1,871)
Comprehensive income	$ 25,889	$ 23,516	$ 19,927

Statements of Consolidated Shar

Statements of Consolidated Shareholders' Equity - USD ($) $ in Thousands	Total	Common shares	Additional paid-in capital	Common shares subscribed, unissued	Retained earnings	Accumulated other comprehensive income (loss), net of tax	Common shares held in treasury	Common shares subscription receivable
Common shares, at beginning of year at Dec. 31, 2014		34,697,000
Balance at beginning of year, value at Dec. 31, 2014		$ 34,697	$ 9,520	$ 9,381	$ 114,504		$ (138,155)	$ 5,600
Increase (decrease) in stockholders' equity [Roll Forward]
Reclassifications of temporary to permanent equity, shares		444,000
Reclassifications of temporary to permanent equity, value		$ 444
Share subscriptions, beginning balance, shares at Dec. 31, 2014				(952,000)				(952,000)
Balance at beginning of year, shares at Dec. 31, 2014							16,584,000
Balance at the beginning of the year at Dec. 31, 2014	$ (11,523)					$ (11,523)
Increase (decrease) in stockholders' equity [Roll Forward]
Shares purchased, value							$ (25,395)
Shares sold to employees, value			6,066				2,198
Options exercised, value			(152)				(1,225)
Subscription shares, issued, value			83				$ 698
Stock-based compensation			2,357
Change in common shares related to 401KSOP and ESOP related shares					(10,332)
Adjustments to additional paid in capital, other			6,466		0
Common shares, issued, value				$ (676)				$ (1,434)
Common shares, issued, shares				(68,000)				(68,000)
Cancellations, value				$ (114)				$ (60)
Cancellations, shares				(12,000)				(12,000)
Net income	21,798				21,798
Dividends					(2,663)
Currency translation adjustments						(5,093)
Defined benefit pension plans	(3,222)					3,222
Shares purchased, shares							1,648,000
Shares sold							(576,000)
Options exercised, shares							(143,000)
Subscription shares, issued, shares							(86,000)
Balance at ending of year, value at Dec. 31, 2015	$ 14,450	$ 35,141	24,340	$ 8,591	123,307		$ (159,429)	$ 4,106
Share subscriptions, ending balance, shares at Dec. 31, 2015				(872,000)				(872,000)
Balance at ending of year, shares at Dec. 31, 2015	17,714,000						17,427,000
Balance at the end of the year at Dec. 31, 2015	$ (13,394)					(13,394)
Common shares, at end of year at Dec. 31, 2015	35,140,708	35,141,000
Increase (decrease) in stockholders' equity [Roll Forward]
Reclassifications of temporary to permanent equity, shares		716,000
Reclassifications of temporary to permanent equity, value		$ 716
Shares purchased, value							$ (25,290)
Shares sold to employees, value			4,182				5,298
Options exercised, value			(992)				(2,442)
Subscription shares, issued, value			21				$ 449
Stock-based compensation			2,860
Change in common shares related to 401KSOP and ESOP related shares					(9,043)
Adjustments to additional paid in capital, other			11,215		0
Common shares, issued, value				$ (325)				$ (1,104)
Common shares, issued, shares				(32,000)				(32,000)
Cancellations, value				$ (57)				$ (29)
Cancellations, shares				(6,000)				(6,000)
Net income	$ 22,284				22,284
Dividends					(2,597)
Currency translation adjustments						744
Defined benefit pension plans	$ (488)					488
Shares purchased, shares	1,492,082						1,492,000
Shares sold	(617,784)						(617,000)
Options exercised, shares							(262,000)
Subscription shares, issued, shares							(49,000)
Balance at ending of year, value at Dec. 31, 2016	$ 27,978	$ 35,857	41,626	$ 8,209	133,951		$ (176,530)	$ 2,973
Share subscriptions, ending balance, shares at Dec. 31, 2016				(834,000)				(834,000)
Balance at ending of year, shares at Dec. 31, 2016	17,866,000						17,991,000
Balance at the end of the year at Dec. 31, 2016	$ (12,162)					(12,162)
Common shares, at end of year at Dec. 31, 2016	35,856,856	35,857,000
Increase (decrease) in stockholders' equity [Roll Forward]
Reclassifications of temporary to permanent equity, shares		590,000
Reclassifications of temporary to permanent equity, value		$ 590
Shares purchased, value							$ (30,566)
Shares sold to employees, value			5,690				5,206
Options exercised, value			76				(2,634)
Subscription shares, issued, value			(35)				$ 929
Stock-based compensation			1,220
Change in common shares related to 401KSOP and ESOP related shares					(9,885)
Adjustments to additional paid in capital, other			9,977		162
Common shares, subscribed, value	$ (12,563)
Common shares, subscribed, shares	(1,275,428)
Common shares, issued, value				$ (567)				$ (1,123)
Common shares, issued, shares				(59,000)				(59,000)
Cancellations, value				$ (113)				$ (75)
Cancellations, shares				(11,000)				(11,000)
Net income	$ 22,120				22,120
Dividends					(2,513)
Currency translation adjustments						2,196
Defined benefit pension plans	$ (1,574)					1,573
Shares purchased, shares	1,697,727						1,698,000
Shares sold	(662,806)						(663,000)
Options exercised, shares	(138,107)						(242,000)
Subscription shares, issued, shares							(91,000)
Balance at ending of year, value at Dec. 31, 2017	$ 37,870	$ 36,447	$ 58,554	$ 7,529	$ 143,835		$ (198,327)	$ 1,775
Share subscriptions, ending balance, shares at Dec. 31, 2017				(764,000)				(764,000)
Balance at ending of year, shares at Dec. 31, 2017	17,754,000						18,693,000
Balance at the end of the year at Dec. 31, 2017	$ (8,393)					$ (8,393)
Common shares, at end of year at Dec. 31, 2017	36,446,890	36,447,000

Statement of Consolidated Share

Statement of Consolidated Shareholders' Equity (Parenthetical)	12 Months Ended
	Dec. 31, 2017$ / shares	Dec. 31, 2016$ / shares	Dec. 31, 2015$ / shares
Dividends declared per share	$ 0.100	$ 0.100	$ 0.100
Stock split, conversion ratio	2

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 22,120	$ 22,284	$ 21,798
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	50,702	47,284	44,677
Amortization	2,384	2,306	2,214
Gain on sale of assets	(3,989)	(4,664)	(2,026)
Deferred income taxes	3,753	60	(2,975)
Other	2,581	1,286	2,399
Changes in operating assets and liabilities:
Accounts receivable	(20,784)	(26,133)	(8,403)
Accounts payable and accrued expenses	6,164	2,454	1,722
Self-insurance accruals	4,856	2,499	1,446
Other assets, net	(11,011)	7,994	1,837
Adjustments to reconcile net income to net cash provided by operating activities	34,656	33,086	40,891
Net cash provided by operating activities	56,776	55,370	62,689
Capital expenditures:
Equipment	(53,128)	(54,147)	(52,466)
Land and buildings	(3,972)	(2,499)	(3,581)
Proceeds from sales of property and equipment	5,034	5,635	2,650
Purchases of businesses	(7,452)	(3,797)	(2,649)
Net cash used in investing activities	(59,518)	(54,808)	(56,046)
Financing activities
Revolving credit facility borrowings/(payments), net	33,000	12,500	10,000
Borrowings/(payments) of notes payable	(2,144)	656	6,720
Payments of long-term debt and capital leases	(6,548)	(5,142)	(6,624)
Purchase of common shares for treasury	(30,404)	(25,290)	(25,395)
Sale of common shares from treasury	13,820	11,019	9,328
Cash received on common-share subscriptions	1,199	1,133	1,494
Dividends	(2,513)	(2,597)	(2,663)
Net cash provided by (used in) financing activities	6,410	(7,721)	(7,140)
Effect of exchange rate changes on cash	447	135	(1,888)
(Decrease) Increase in cash	4,115	(7,024)	(2,385)
Cash, beginning of year	9,006	16,030	18,415
Cash, end of year	$ 13,121	$ 9,006	$ 16,030

Our Business

Our Business	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Our Business	Our Business We provide a wide range of arboricultural, horticultural, environmental and consulting services to residential, utility, commercial and government entities throughout the United States and Canada. We have two reportable operating segments organized by type or class of customer: Residential and Commercial, and Utility. Residential and Commercial --Residential and Commercial provides services to our residential and commercial customers including: the treatment, preservation, maintenance, removal and planting of trees, shrubs and other plant life; the practice of landscaping, grounds maintenance, tree surgery, tree feeding and tree spraying; the application of fertilizer, herbicides and insecticides; and, natural resource management and consulting, forestry research and development, and environmental planning. Utility --Utility is principally engaged in providing services to our utility customers--investor-owned, municipal utilities, and rural electric cooperatives--including: the practice of line-clearing and vegetation management around power lines, rights-of-way and chemical brush control; and, natural resource management and consulting, forestry research and development and environmental planning. We also maintain research, technical support and laboratory diagnostic facilities. When we refer to “we,” “us,” “our,” “Davey Tree,” and the “Company,” we mean The Davey Tree Expert Company, unless the context indicates otherwise.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation and Basis of Presentation --The consolidated financial statements include the accounts of Davey Tree and our wholly-owned subsidiaries and were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as codified in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC"). Intercompany accounts and transactions have been eliminated in consolidation. Per Common Share Information --We have given retroactive consideration to the two -for-one stock split of our common shares effective June 1, 2017 including all common share and per share data. Use of Estimates in Financial Statement Preparation --The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts. Estimates are used for, but not limited to, accounts receivable valuation, depreciable lives of fixed assets, self-insurance accruals, and revenue recognition. Actual results could differ from those estimates. Property and Equipment --Property and equipment are stated at cost. Repair and maintenance costs are expensed as incurred. Depreciation is computed for financial reporting purposes by the straight-line method for land improvements, building and leasehold improvements and by the declining-balance method for equipment, based on the estimated useful lives of the assets, as follows: Land improvements 5 to 20 years Buildings 5 to 30 years Equipment 3 to 10 years Leasehold improvements Shorter of lease term or estimated useful life; ranging from 5-to-20 years Intangible Assets --Intangible assets with finite lives, primarily customer lists, noncompete agreements and tradenames, are amortized by the straight-line method based on their estimated useful lives, ranging from one-to-ten years. Long-Lived Assets --We assess potential impairment to our long-lived assets, other than goodwill, when there is evidence that events or changes in circumstances have made recovery of the asset’s carrying value unlikely and the carrying amount of the asset exceeds the estimated future undiscounted cash flow. In the event the assessment indicates that the carrying amounts B. Summary of Significant Accounting Policies (continued) may not be recoverable, an impairment loss would be recognized to reduce the asset’s carrying amount to its estimated fair value based on the present value of the estimated future cash flows. Goodwill --Goodwill is recorded when the cost of acquired businesses exceeds the fair value of the identified net assets acquired. Goodwill is not amortized, but tested for impairment annually or when events or circumstances indicate that impairment may have occurred. Annually, we perform the impairment tests for goodwill during the fourth quarter. Impairment of goodwill is tested at the reporting-unit level, which for us are also our business segments. Impairment of goodwill is tested by comparing the reporting unit’s carrying value, including goodwill, to the fair value of the reporting unit. The fair values of the reporting units are estimated using discounted projected cash flows. If the carrying value of the reporting unit exceeds its fair value, goodwill is considered impaired and an impairment loss should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. We conducted our annual impairment tests and determined that no impairment loss was required to be recognized in 2017 or for any prior periods. There were no events or circumstances from the date of our assessment through December 31, 2017 that would impact this conclusion. Self-Insurance Accruals --We are generally self-insured for losses and liabilities related primarily to workers’ compensation, vehicle liability and general liability claims. We use commercial insurance as a risk-reduction strategy to minimize catastrophic losses. Ultimate losses are accrued based upon estimates of the aggregate liability for claims incurred using certain actuarial assumptions followed in the insurance industry and based on Company-specific experience. Our self-insurance accruals include claims for which the ultimate losses will develop over a period of years. Accordingly, our estimates of ultimate losses can change as claims mature. Our accruals also are affected by changes in the number of new claims incurred and claim severity. The methods for estimating the ultimate losses and the total cost of claims were determined by third-party consulting actuaries; the resulting accruals are reviewed by management, and any adjustments arising from changes in estimates are reflected in income. The workers' compensation accruals are discounted as the amount and timing of cash payments related to those accruals are reliably determinable given the nature of workers' compensation benefits and the level of historical claim volume to support the actuarial assumptions and judgments used to derive the expected loss payment pattern. The workers' compensation accruals are discounted using an interest rate that approximates the long-term investment yields over the expected payment pattern of unpaid losses. Our self-insurance accruals are based on estimates and, while we believe that the amounts accrued are adequate and not excessive, the ultimate claims may be in excess of or less than the amounts provided. Stock-Based Compensation -- Stock-based compensation cost for all share-based payment plans is measured at fair value on the date of grant and recognized over the employee service period on the straight-line recognition method for awards expected to vest. The fair value of all stock-based payment plans—stock option plans, stock-settled stock appreciation rights, and performance-based restricted stock units as well as our Employee Stock Purchase Plan—is determined by the number of awards granted and the price of our common stock. The fair value of each award is estimated on the date of grant using a binomial option-pricing model. The binomial model considers a range of assumptions related to volatility, risk-free interest rate and employee exercise behavior. Expected volatilities utilized in the binomial model are based on historical volatility of our share prices and other factors. Similarly, the dividend yield is based on historical experience and expected future changes. The binomial model also incorporates exercise assumptions based on an analysis of historical data. The expected life of the stock-based awards is derived from the output of the binomial model and represents the period of time that awards granted are expected to be outstanding. Defined Benefit Pension Plans --We record annual expenses relating to our defined benefit pension plans based on calculations that include various actuarial assumptions, including discount rates and expected long-term rates of return on plan assets. Actuarial assumptions are reviewed annually with modifications made to the assumptions, if necessary, based on current rates and trends. The effects of the actuarial gains or losses are amortized over future service periods. The funded status (that is, the projected benefit obligation less the fair value of plan assets) for each plan is reported in our balance sheet B. Summary of Significant Accounting Policies (continued) using a December 31 measurement date. Changes in the funded status of the plans are recognized in the year in which the changes occur and reported in comprehensive income (loss). Income Taxes --We compute taxes on income in accordance with the tax rules and regulations where the income is earned. The income tax rates imposed by these taxing authorities vary. Taxable income may differ from pretax income for financial reporting purposes. We compute and recognize deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax bases of our assets and liabilities. Changes in tax rates and laws are reflected in income in the period when such changes are enacted. We account for uncertain tax positions by recognizing the financial statement effects of a tax position only when, based upon the technical merits, it is more-likely-than-not that the position will be sustained upon examination. Earnings Per Share --Basic earnings per share is determined by dividing the income available to common shareholders by the weighted-average number of common shares outstanding. Diluted earnings per share is computed similarly to basic earnings per share except that the weighted-average number of shares is increased to include the effect of stock awards that were granted and outstanding during the period. Revenue Recognition --Revenues from residential and commercial services are recognized as the services are provided and amounts are determined to be collectible. Revenues from contractual arrangements, primarily with utility services customers, are recognized based on costs incurred to total estimated contract costs. During the performance of such contracts, estimated final contract prices and costs are periodically reviewed and revisions are made, as required, to the revenue recognized. On cost-plus-fee contracts, revenue is recognized to the extent of costs incurred plus a proportionate amount of fees earned, and on time-and-material contracts, revenue is recognized to the extent of billable rates times hours worked, plus material and other reimbursable costs incurred. Revisions arise in the normal course of providing services to utility services customers and generally relate to changes in contract specifications and cost allowability. Such revisions are recorded when realization is probable and can be reliably estimated. Concentration of Credit Risk --Credit risk represents the accounting loss that would be recognized if the counterparties failed to perform as contracted. The principal financial instruments subject to credit risk follow: Cash --To limit our exposure, we transact our business and maintain banking relationships with high credit-quality financial institutions. Accounts Receivable --Our residential and commercial customers are located geographically throughout the United States and Canada and, as to commercial customers, within differing industries; thus, minimizing credit risk. The credit exposure of utility services customers is directly affected by conditions within the utility industries as well as the financial condition of individual customers. One utility customer approximated 11% of revenues during 2017 , 12% in 2016 and 11% in 2015 . To reduce credit risk, we evaluate the credit of customers, but generally do not require advance payments or collateral. Exposure to losses on receivables is principally dependent on each customer’s financial condition. Foreign Currency Translation and Transactions --Assets and liabilities of our Canadian operations are translated into U.S. dollars using year-end exchange rates, and revenues and expenses are translated using exchange rates as determined throughout the year. Gains or losses resulting from translation are included in the consolidated balance sheet, classified in shareholders’ equity as a separate component of accumulated other comprehensive income (loss). Gains or losses resulting from Canadian-dollar transactions with the Canadian operations are translated to U.S. dollars at the rates of exchange prevailing at the dates of the transactions. The effect of the transactions gain or loss is classified in the statement of operations as a component of other nonoperating income (expense), net. Interest Rate Risk Management --We have entered into interest rate contracts, from time-to-time, with the objective of altering interest rate exposures related to variable rate debt. In the interest rate contracts, we have agreed with a financial B. Summary of Significant Accounting Policies (continued) institution to exchange, at specified intervals, the difference between fixed and floating interest amounts calculated on an agreed-upon notional principal amount. During the year ended December 31, 2017, we did not enter into any interest rate contracts. Comprehensive Income (Loss) --Comprehensive income (loss) includes net income and other comprehensive income or loss. Other comprehensive income (loss) refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income but are excluded from net income as these amounts are recorded directly as an adjustment to shareholders’ equity, net of tax.

Recent Accounting Guidance

Recent Accounting Guidance	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Guidance	Recent Accounting Guidance Accounting Standards Adopted in 2017 Accounting Standards Update 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting --In March 2016, the FASB issued ASU 2016-09, “Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” with the objective to simplify several aspects of the accounting for share-based payment transactions, including: the income tax consequences; classification of awards as either equity or liabilities; classification of certain items on the statement of cash flows; and, accounting for forfeitures. ASU 2016-09 became effective for Davey Tree on January 1, 2017 and we elected to make an accounting policy change to recognize forfeitures as they occur. The adoption impact on the consolidated condensed balance sheet was a cumulative-effect adjustment of $162 , increasing opening retained earnings and decreasing additional paid-in capital. Accounting Standards Update 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment -- In January 2017, the FASB issued ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350),” which simplifies the subsequent measurement of goodwill by eliminating Step 2 of the goodwill impairment test, which required entities to fair value their assets and liabilities using procedures that would be followed in an assumed business combination to arrive at the impairment charge. Under ASU 2017-04, the goodwill impairment test is performed by comparing the fair value of the reporting unit with its carrying amount and an impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. The update is effective for annual or interim periods beginning after December 15, 2019, which for Davey Tree is January 1, 2020. The Company early adopted ASU 2017-04 during the fourth quarter 2017 and the adoption had no effect on the Company’s consolidated financial statements or related disclosures. Accounting Standards Update 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting --In May 2017, the FASB issued ASU 2017-09, “Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting,” which provides guidance on which changes in the terms or conditions of a share-based payment award require modification accounting under Topic 718. Modification accounting is required for changes in terms or conditions unless the fair value, vesting condition and classification of the modified award is the same as the original award. The update is effective for annual and interim periods beginning after December 15, 2017, which for Davey Tree would be January 1, 2018. The Company early adopted ASU 2017-09 during the fourth quarter 2017 and the adoption had no effect on the Company's consolidated financial statements or related disclosures. Accounting Standards Not Yet Adopted Accounting Standards Update 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the FASB Emerging Issues Task Force) --In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which provides guidance on how cash receipts and cash payments related to eight specific cash flow issues are presented and classified in the statement of cash flows, with the objective of reducing the existing diversity in practice. The update is effective for annual periods beginning after December 15, 2017, which for Davey Tree would be January 1, 2018. Early adoption is permitted. We do not expect the adoption of ASU 2016-15 to have a material impact on our consolidated financial statements. C. Recent Accounting Guidance (continued) Accounting Standards Update 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost --In March 2017, the FASB issued ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” which changes the presentation of net periodic benefit cost related to employer sponsored defined benefit plans and other postretirement benefits. Under ASU 2017-07, service costs will be included within the same income statement line item as other compensation costs arising from services rendered by pertinent employees during the period. The other components of net periodic benefit pension cost will be presented separately outside of income from operations. Additionally, only service costs may be capitalized in assets. ASU 2017-07 is effective for fiscal years beginning after December 15, 2017, which for Davey Tree is January 1, 2018. Management is currently assessing the impact of the new standard on the Company’s consolidated financial statements and does not expect the adoption to have a material effect on the Company's consolidated financial statements. Accounting Standards Update 2014-09, Revenue from Contracts with Customers (Topic 606 )--In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” which will replace all current U.S. GAAP guidance on revenue recognition and eliminate all industry-specific guidance. The new revenue recognition guidance provides a unified model to determine when and how revenue is recognized. The underlying principle is that an entity should recognize revenue to depict the transfer of promised goods and services to customers in an amount that reflects the consideration which the entity expects to receive in exchange for those goods and services. The guidance provides a five-step analysis of transactions to determine when and how revenue is recognized. Other major provisions include capitalization of certain contract costs, consideration of the time value of money in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The guidance also requires enhanced information to be presented in the financial statements regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. This guidance is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. An entity can elect to apply the guidance under one of the following two methods: (i) retrospectively to each prior reporting period presented, referred to as the full retrospective method, or (ii) retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings, referred to as the modified retrospective method. The Company adopted the new standard on January 1, 2018, using the modified retrospective method. Management has substantially completed the process of evaluating the effect of the adoption, which included reviewing representative samples of customer contracts for each revenue stream, analyzing those contracts under the new revenue standard, and comparing the conclusions to the current accounting policies and practices to identify potential changes, and determined that the adoption of ASU No. 2014-09 will not have a material impact on the Company’s financial statements. Based on management’s evaluation process, the majority of the Company’s revenue arrangements generally consist of a single performance obligation to transfer promised services over time. The Company is entitled to consideration for the services as they are performed, and the timing and amount of revenue recognized based on ASU No. 2014-09 is consistent with the Company’s revenue recognition policy under previous guidance. However, the Company will be required to expand its revenue disclosures as a result of adopting the new standard, which will primarily include disaggregation of revenue, changes in contract assets and liabilities, information about our performance obligations and significant judgments made in the application of the new standard. The Company has documented this evaluation and has implemented processes and controls for its revenue streams as warranted by the guidance. Accounting Standards Update 2016-02, Leases (Topic 842)-- In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” ASU 2016-02 establishes a comprehensive new lease accounting model. The new standard: (a) clarifies the definition of a lease; (b) requires a dual approach to lease classification similar to current lease classifications; and, (c) causes lessees to recognize leases on the balance sheet as a lease liability with a corresponding right-of-use asset for leases with a lease-term of more than twelve months. The new standard is effective for interim and annual periods beginning after December 15, 2018, which for Davey Tree would be January 1, 2019. Early adoption is permitted. The new standard requires a modified retrospective transition for capital or operating leases existing at or entered into after the beginning of the earliest comparative period presented in the financial statements, but it does not require transition accounting for leases that expire C. Recent Accounting Guidance (continued) prior to the date of initial application. The Company plans to adopt during the first quarter 2019. We are are in the process of identifying the population of leases affected and determining the information required to calculate the lease liability and right-of-use asset in addition to evaluating software to assist with future reporting.

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combinations	Business Combinations Our investments in businesses were: (a) $13,264 in 2017 , including liabilities assumed of $2,713 and debt issued of $3,099 ; (b) $4,888 in 2016 , including liabilities assumed of $216 and debt issued of $875 ; and (c) $4,149 in 2015 , including no liabilities assumed and debt issued of $1,500 . The net assets of the businesses acquired are accounted for under the acquisition method and were recorded at their fair values at the dates of acquisition. The excess of the purchase price over the estimated fair values of the net assets acquired was recorded as an increase in goodwill of approximately $5,131 in 2017 (all of which is deductible for tax purposes), $817 in 2016 (all of which is deductible for tax purposes) and $1,410 goodwill in 2015 (all of which is deductible for tax purposes). The results of operations of acquired businesses have been included in the consolidated statements of operations beginning as of the effective dates of acquisition. The effect of these acquisitions on our consolidated revenues and results of operations, either individually or in the aggregate, for the years ended December 31, 2017 , 2016 or 2015 was not significant.

Accounts Receivable, Net and Su

Accounts Receivable, Net and Supplemental Balance Sheet Information	12 Months Ended
	Dec. 31, 2017
Accounts Receivable, Net and Supplemental Balance Sheet Information [Abstract]
Accounts Receivable, Net and Supplemental Balance Sheet Information	Accounts Receivable, Net and Supplemental Balance Sheet Information Accounts receivable, net, consisted of the following: December 31, 2017 2016 Accounts receivable $ 143,244 $ 128,202 Receivables under contractual arrangements 29,895 21,541 173,139 149,743 Less allowances for doubtful accounts 4,468 3,609 $ 168,671 $ 146,134 Receivables under contractual arrangements consist of work-in-process in accordance with the terms of contracts, primarily, with utility services customers. E. Accounts Receivable, Net and Supplemental Balance Sheet Information (continued) The following items comprise the amounts included in the balance sheets: December 31, Other current assets 2017 2016 Refundable income taxes $ 587 $ 548 Other 784 1,315 Total $ 1,371 $ 1,863 December 31, Other assets, noncurrent 2017 2016 Assets invested for self-insurance $ 19,422 $ 15,492 Investment--cost-method affiliate 1,218 1,168 Deferred income taxes 4,815 11,129 Other 3,701 3,565 Total $ 29,156 $ 31,354 December 31, Accrued expenses 2017 2016 Employee compensation $ 20,794 $ 18,438 Accrued compensated absences 9,267 9,215 Self-insured medical claims 3,193 2,961 Customer advances, deposits 1,672 2,997 Income taxes payable 3,443 953 Taxes, other than income 2,279 2,166 Other 2,168 929 Total $ 42,816 $ 37,659 December 31, Other liabilities, noncurrent 2017 2016 Pension and retirement plans $ 14,759 $ 15,982 Other 5,207 4,837 Total $ 19,966 $ 20,819

Supplemental Operating Informat

Supplemental Operating Information	12 Months Ended
	Dec. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Other Nonoperating Income and Expense	Supplemental Operating Information Other Nonoperating (Expense) Income, Net Other nonoperating (expense) income, net, included in the statements of operations follows: Year Ended December 31, 2017 2016 2015 Other nonoperating expense, net $ (4,417 ) $ (3,989 ) $ (5,744 ) Other nonoperating (expense) income, net, includes foreign currency (i) gains of $55 for 2017 , (ii) gains of $113 for 2016 , and (iii) losses of $854 for 2015 on the intercompany balances of our Canadian operations.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Supplemental cash flow information follows: Year Ended December 31, Supplemental cash flow information 2017 2016 2015 Interest paid $ 5,096 $ 4,329 $ 3,386 Income taxes paid, net 10,005 10,578 16,679 Noncash transactions: Debt issued for purchases of businesses $ 3,099 $ 875 $ 1,500 Detail of acquisitions: Assets acquired: Receivables $ 1,753 $ — $ — Operating supplies — 157 — Prepaid expense 128 55 — Equipment 1,904 2,485 1,264 Deposits and other 52 — 11 Intangibles 4,296 1,374 1,464 Goodwill 5,131 817 1,410 Liabilities assumed (2,713 ) (216 ) — Debt issued for purchases of businesses (3,099 ) (875 ) (1,500 ) Cash paid $ 7,452 $ 3,797 $ 2,649

Identified Intangible Assets an

Identified Intangible Assets and Goodwill, Net	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Identified Intangible Assets and Goodwill, Net [Text Block]	Identified Intangible Assets and Goodwill, Net The carrying amount of the identified intangibles and goodwill acquired in connection with our investments in businesses were as follows: Weighted-Average Amortization Period (Years) December 31, 2017 December 31, 2016 Carrying Amount Accumulated Amortization Carrying Amount Accumulated Amortization Amortized intangible assets: Customer lists/relationships 2.8 years $ 21,487 $ 16,846 $ 17,822 $ 15,171 Employment-related 2.2 years 7,333 6,624 7,032 6,386 Tradenames 2.9 years 5,978 5,134 5,634 4,860 Total 34,798 $ 28,604 30,488 $ 26,417 Less accumulated amortization 28,604 26,417 Identified intangibles, net 6,194 4,071 Unamortized intangible assets: Goodwill Not amortized 35,477 30,305 $ 41,671 $ 34,376 The changes in the carrying amounts of goodwill, by segment, for the year ended December 31, 2017 follow: Balance at January 1, 2017 Acquisitions Translation and Other Adjustments Balance at December 31, 2017 Utility $ 3,424 $ — $ — $ 3,424 Residential and Commercial 26,881 5,131 41 32,053 Total $ 30,305 $ 5,131 $ 41 $ 35,477 Estimated future aggregate amortization expense of intangible assets -- The estimated aggregate amortization expense of intangible assets, as of December 31, 2017 , in each of the next five years follows: Estimated Future Amortization Expense Year ending December 31, 2018 $ 1,581 2019 1,451 2020 1,265 2021 826 2022 596

Short and Long-Term Debt and Co

Short and Long-Term Debt and Commitments Related to Letters of Credit	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Short and Long-Term Debt and Commitments Related to Letters of Credit [Text Block]	Short and Long-Term Debt and Commitments Related to Letters of Credit Short-term debt consisted of the following: December 31, 2017 2016 Notes payable $ 149 $ — Current portion of long-term debt 16,166 16,701 $ 16,315 $ 16,701 At December 31, 2017 , we also had unused short-term lines of credit with several banks totaling $7,042 , generally at the banks' prime rate or LIBOR plus a margin adjustment of .75% to 1.50% . Long-term debt consisted of the following: December 31, 2017 2016 Revolving credit facility Swing-line borrowings $ — $ 10,000 LIBOR borrowings 100,000 57,000 100,000 67,000 Senior unsecured notes 18,000 24,000 Term loans 16,242 16,151 134,242 107,151 Less debt issuance costs 725 333 Less current portion 16,166 16,701 $ 117,351 $ 90,117 Revolving Credit Facility and 5.09% Senior Unsecured Notes -- In October 2017, the Company amended its revolving credit facility. The amended and restated credit agreement, which expires in October 2022, permits borrowings as defined up to $250,000 including a letter of credit sublimit of $100,000 and a swing-line commitment of $25,000 . Under certain circumstances, the amount available under the revolving credit facility may be increased to $325,000 . The revolving credit facility contains certain affirmative and negative covenants customary for this type of facility and includes financial covenant ratios with respect to a maximum leverage ratio (not to exceed 3.00 to 1.00 with exceptions in case of material acquisitions) and a minimum interest coverage ratio (not less than 3.00 to 1.00), in each case subject to certain further restrictions as described in the Credit Agreement. On July 22, 2010, we issued $30,000 of 5.09% Senior Unsecured Notes, Series A, due July 22, 2020 (the " 5.09% Senior Notes"). The 5.09% Senior Notes were issued pursuant to a Master Note Purchase Agreement (the “Purchase Agreement”), between the Company and the purchasers of the 5.09% Senior Notes. The net proceeds of the 5.09% Senior Notes were used to pay down borrowings under our revolving credit facility. The 5.09% Senior Notes are equal in right of payment with our revolving credit facility and all other senior unsecured obligations of the Company. Interest is payable semiannually and five equal, annual principal payments commenced on July 22, 2016 (the sixth anniversary of issuance). The Purchase Agreement contains customary events of default and covenants related to limitations on indebtedness and transactions with affiliates and the maintenance of certain financial ratios. As of December 31, 2017 , we had unused commitments under the revolving credit facility approximating $146,912 , and $103,088 committed, which consisted of borrowings of $100,000 and issued letters of credit of $3,088 . Borrowings outstanding bear interest, at the Company's option, of either (a) the base rate or (b) LIBOR plus a margin adjustment ranging from .875% to 1.50% --with the margin adjustments in both instances based on the Company's leverage ratio at the time of borrowing. The base rate is the greater of (i) the agent bank’s prime rate, (ii) LIBOR plus 1.5% , or (iii) the federal funds rate I. Short and Long-Term Debt and Commitments Related to Letters of Credit (continued) plus .5% . A commitment fee ranging from .10% to .225% is also required based on the average daily unborrowed commitment. Term Loans, Weighted-Average Interest Rate --The weighted-average interest on the term loans approximated 3.75% at December 31, 2017 and 3.56% at December 31, 2016 . Aggregate Maturities of Long-Term Debt --Aggregate maturities of long-term debt for the five years subsequent to December 31, 2017 were as follows: 2018 -- $16,166 ; 2019 -- $6,890 ; 2020 -- $6,894 ; 2021 -- $4,292 ; and, 2022 -- $100,000 . Accounts Receivable Securitization Facility --In May 2017, Davey Tree amended its Accounts Receivable Securitization Facility (the “AR securitization facility”), to extend the scheduled termination date for an additional one -year period, to May 8, 2018 and increase the limit of the facility from $ 60,000 to $100,000 . Under the AR securitization facility, Davey Tree transfers by selling or contributing current and future trade receivables to a wholly-owned, bankruptcy-remote financing subsidiary which pledges a perfected first priority security interest in the trade receivables--equal to the issued letters of credit ("LCs") as of December 31, 2017 --to the bank in exchange for the bank issuing LCs. Fees payable to the bank include: (a) an LC issuance fee, payable on each settlement date, in the amount of .90% per annum on the aggregate amount of all LCs outstanding plus outstanding reimbursement obligations (e.g., arising from drawn LCs), if any, and (b) an unused LC fee, payable monthly, equal to (i) .35% per annum for each day on which the sum of the total LCs outstanding plus any outstanding reimbursement obligations is greater than or equal to 50% of the facility limit and (ii) .45% per annum for each day on which the sum of the total LCs outstanding plus any outstanding reimbursement obligations is less than 50% of the facility limit. If an LC is drawn and the bank is not immediately reimbursed in full for the drawn amount, any outstanding reimbursement obligation will accrue interest at a per annum rate equal to a reserve-adjusted LIBOR or, in certain circumstances, a base rate equal to the higher of (i) the bank’s prime rate and (ii) the federal funds rate plus .50% and, following any default, 2.00% plus the greater of (a) adjusted LIBOR and (b) a base rate equal to the higher of (i) the bank’s prime rate and (ii) the federal funds rate plus .50% . The agreements underlying the AR securitization facility contains various customary representations and warranties, covenants, and default provisions which provide for the termination and acceleration of the commitments under the AR securitization facility in circumstances including, but not limited to, failure to make payments when due, breach of a representation, warranty or covenant, certain insolvency events or failure to maintain the security interest in the trade receivables, and defaults under other material indebtedness. As of December 31, 2017 , we had issued LCs of $58,150 under the terms of the AR securitization facility. Total Commitments Related to Issued Letters of Credit --As of December 31, 2017 , total commitments related to issued letters of credit were $63,242 , of which $3,088 were issued under the revolving credit facility, $58,150 were issued under the AR securitization facility, and $2,004 were issued under short-term lines of credit. As of December 31, 2016 , total commitments related to issued letters of credit were $64,225 , of which $4,071 were issued under the revolving credit facility, $58,150 were issued under the AR securitization facility and $2,004 were issued under short-term lines of credit.

Self-Insurance Accruals

Self-Insurance Accruals	12 Months Ended
	Dec. 31, 2017
Self-Insurance Accruals [Abstract]
Self-Insurance Accruals [Text Block]	Self-Insurance Accruals Components of our self-insurance accruals for workers’ compensation, vehicle liability and general liability follow: December 31, 2017 2016 Workers' compensation $ 40,764 $ 38,811 Present value discount 2,346 2,236 38,418 36,575 Vehicle liability 5,536 4,763 General liability 23,740 21,500 Total 67,694 62,838 Less current portion 23,782 23,092 Noncurrent portion $ 43,912 $ 39,746 The changes in our self-insurance accruals and the discount rate used for the workers’ compensation accrual are summarized in the table below. December 31, 2017 2016 Balance, beginning of year $ 62,838 $ 60,339 Provision for claims 34,884 33,404 Payment of claims 30,028 30,905 Balance, end of year $ 67,694 $ 62,838 Workers' compensation discount rate 2.00 % 2.20 %

Lease Obligations

Lease Obligations	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Lease Obligations [Text Block]	Lease Obligations Assets acquired under capital leases and included in property and equipment consisted of the following: December 31, 2017 2016 Equipment $ 3,481 $ 2,528 Less accumulated amortization 805 160 $ 2,676 $ 2,368 We also lease facilities under noncancelable operating leases, which are used for district office and warehouse operations. These leases extend for varying periods of time up to five years and, in some cases, contain renewal options. Minimum rental commitments under all capital and noncancelable operating leases, as of December 31, 2017 , were as follows: Lease Obligations Minimum lease obligations Capital Operating Year ending December 31, 2018 $ 694 $ 7,243 2019 694 5,326 2020 682 3,945 2021 558 2,354 2022 — 1,794 2023 and after — 6,973 Total minimum lease payments 2,628 $ 27,635 Amounts representing interest 118 Present value of net minimum lease payments 2,510 Less current portion 651 Long-term capital lease obligations, December 31, 2017 $ 1,859 Total rent expense under all operating leases was $7,998 in 2017 , $7,536 in 2016 and $7,398 in 2015 .

Common Shares, Redeemable Commo

Common Shares, Redeemable Common Shares and Preferred Shares	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Common Shares, Redeemable Common Shares and Preferred Shares [Text Block]	Common Shares, Redeemable Common Shares and Preferred Shares We have given retroactive consideration to the two -for-one stock split of our common shares effective June 1, 2017 including all common share and per share data. Preferred Shares --We have authorized a class of 4,000,000 preferred shares, no par value, of which none were issued. Redeemable Common Shares - Our Davey 401KSOP and ESOP Plan includes a put option for shares of the Company’s common stock distributed from the plan. Due to the Company’s obligation under the put option, shares held in the Davey 401KSOP and ESOP Plan as well as distributed shares subject to the put option are reclassified from permanent equity to temporary equity. The number of redeemable common shares for each of the three years in the period ended December 31, 2017 was as follows: 2017-- 6,467,027 ; 2016-- 7,056,904 ; and 2015-- 7,773,052 . Common Shares --The number of common shares authorized is 48,000,000 , par value $1.00 . The number of common shares issued during each of the three years in the period ended December 31, 2017 was as follows: 2017-- 36,446,890 ; 2016-- 35,856,856 and 2015-- 35,140,708 . The number of shares in the treasury for each of the three years in the period ended December 31, 2017 was as follows: 2017 -- 18,692,901 ; 2016 -- 17,990,620 ; and 2015 -- 17,427,132 . L. Common Shares, Redeemable Common Shares and Preferred Shares (continued) Our common and redeemable common shares are not listed or traded on an established public trading market, and market prices are, therefore, not available. Semiannually, an independent stock valuation firm determines the fair market value of our common and redeemable common shares based upon our performance and financial condition. Since 1979, we have provided a ready market for all shareholders through our direct purchase of their common shares, although we are under no obligation to do so (other than repurchases pursuant to the put option under the Davey 401KSOP and ESOP Plan, as described in Note N). During 2017 , purchases of common shares, both redeemable and common, totaled 1,697,727 shares for $30,566 in cash; we also had direct sales to directors and employees of 39,564 shares for $700 , excluding those shares issued through either the exercise of options or the Employee Stock Purchase Plan. We also sold 80,178 shares to our 401(k) plan for $1,420 and issued 208,024 shares to participant accounts to satisfy our liability for the 2016 employer match in the amount of $3,661 . The liability accrued at December 31, 2017 for the 2017 employer match was $3,991 . There were also 335,040 shares purchased during 2017 under the Employee Stock Purchase Plan. Common and Redeemable Shares Outstanding -- The table below reconciles the activity of the common and redeemable shares outstanding: Common Shares Net of Treasury Shares Redeemable Shares Total Shares outstanding, December 31, 2015 17,713,576 7,773,052 25,486,628 Shares purchased (479,807 ) (1,012,275 ) (1,492,082 ) Shares sold 321,657 296,127 617,784 Stock subscription offering, employee cash purchases 48,730 — 48,730 Options exercised 262,080 — 262,080 Shares outstanding, December 31, 2016 17,866,236 7,056,904 24,923,140 Shares purchased (807,718 ) (890,009 ) (1,697,727 ) Shares sold 362,674 300,132 662,806 Stock subscription offering, employee cash purchases 90,645 — 90,645 Options exercised 241,995 — 241,995 Shares outstanding, December 31, 2017 17,753,832 6,467,027 24,220,859 On December 31, 2017 , we had 24,220,859 common shares outstanding, employee options exercisable to purchase 800,615 common shares, partially-paid subscription for 764,382 common shares and purchase rights outstanding for 309,389 common shares. Stock Subscription Offering --Beginning May 2012, the Company offered to eligible employees and nonemployee directors the right to subscribe to common shares of the Company at $9.85 per share in accordance with the provisions of The Davey Tree Expert Company 2004 Omnibus Stock Plan and the rules of the Compensation Committee of the Company's Board of Directors (collectively, the "plan"). The offering period ended on August 1, 2012 and resulted in the subscription of 1,275,428 common shares for $12,563 at $9.85 per share. Under the plan, a participant in the offering purchasing common shares for an aggregate purchase price of less than $5 had to pay with cash. All participants (excluding Company directors and officers) purchasing $5 or more of the common shares had an option to finance their purchase through a down-payment of at least 10% of the total purchase price and a seven -year promissory note for the balance due with interest at 2% . Payments on the promissory note can be made either by payroll deductions or annual lump-sum payments of both principal and interest. Common shares purchased under the plan have been pledged as security for the payment of the promissory note and the common shares will not be issued until the promissory note is paid-in-full. Dividends will be paid on all subscribed shares, subject to forfeiture to the extent that payment is not ultimately made for the shares. L. Common Shares, Redeemable Common Shares and Preferred Shares (continued) All participants in the offering purchasing in excess of $5 of common shares were granted a "right" to purchase one additional common share at a price of $9.85 per share for every three common shares purchased under the plan. As a result of the stock subscription, employees were granted rights to purchase 423,600 common shares. Each right may be exercised at the rate of one-seventh per year and will expire seven years after the date that the right was granted. Employees may not exercise a right should they cease to be employed by the Company.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is comprised of net income and other adjustments that relate to foreign currency translation adjustments and defined benefit pension plan adjustments. We do not provide income taxes on currency translation adjustments, as the earnings of our Canadian operations are considered to be indefinitely reinvested. The following summarizes the components of other comprehensive income (loss) accumulated in shareholders’ equity: Foreign Currency Translation Adjustments Defined Benefit Pension Plans Accumulated Other Comprehensive Income (Loss) Balance at January 1, 2015 $ (1,151 ) $ (10,372 ) $ (11,523 ) Unrealized gains (losses) (5,093 ) — (5,093 ) Amounts reclassified from accumulated other comprehensive income (loss) — 4,774 4,774 Tax effect — (1,878 ) (1,878 ) Unrecognized amounts from defined benefit pension plans — 538 538 Tax effect — (212 ) (212 ) Net of tax amount (5,093 ) 3,222 (1,871 ) Balance at December 31, 2015 $ (6,244 ) $ (7,150 ) $ (13,394 ) Unrealized gains (losses) 744 — 744 Amounts reclassified from accumulated other comprehensive income (loss) — 2,844 2,844 Tax effect — (1,137 ) (1,137 ) Unrecognized amounts from defined benefit pension plans — (2,032 ) (2,032 ) Tax effect — 813 813 Net of tax amount 744 488 1,232 Balance at December 31, 2016 $ (5,500 ) $ (6,662 ) $ (12,162 ) Unrealized gains (losses) 2,195 — 2,195 Amounts reclassified from accumulated other comprehensive income (loss) — 4,822 4,822 Tax effect — (1,962 ) (1,962 ) Unrecognized amounts from defined benefit pension plans — (2,169 ) (2,169 ) Tax effect — 883 883 Net of tax amount 2,195 1,574 3,769 Balance at December 31, 2017 $ (3,305 ) $ (5,088 ) $ (8,393 ) The amounts reclassified from accumulated other comprehensive income (loss) related to defined benefit pension plans for 2017 , 2016 and 2015 are included in net periodic pension expense and classified in the statement of operations as costs and expenses, general and administrative.

The Davey 401KSOP and Employee

The Davey 401KSOP and Employee Stock Ownership Plan	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
The Davey 401KSOP and Employee Stock Ownership Plan	The Davey 401KSOP and Employee Stock Ownership Plan On March 15, 1979, we consummated a plan, which transferred control of the Company to our employees. As a part of this plan, we initially sold 120,000 common shares (presently, 11,520,000 common shares adjusted for stock splits) to our Employee Stock Ownership Trust (“ESOT”) for $2,700 . The Employee Stock Ownership Plan (“ESOP”), in conjunction with the related ESOT, provided for the grant to certain employees of certain ownership rights in, but not possession of, the common shares held by the trustee of the ESOT. Annual allocations of shares have been made to individual accounts established for the benefit of the participants. Defined Contribution and Savings Plans-- Most employees are eligible to participate in The Davey 401KSOP and ESOP. Effective January 1, 1997, the plan commenced operations and retained the existing ESOP participant accounts and incorporated a deferred savings plan (a "401(k) plan") feature. Participants in the 401(k) plan are allowed to make before-tax contributions, within Internal Revenue Service established limits, through payroll deductions. Effective January 1, 2009, we match, in either cash or our common shares, 100% of the first one percent and 50% of the next three percent of each participant's before-tax contribution, limited to the first four percent of the employee's compensation deferred each year. All nonbargaining domestic employees who attained age 21 and completed one year of service are eligible to participate. In May 2004, we adopted the 401K Match Restoration Plan, a defined contribution plan that supplements the retirement benefits of certain employees that participate in the savings plan feature of The Davey 401KSOP and ESOP Plan, but are limited in contributions because of tax rules and regulations. The Davey 401KSOP and ESOP Plan includes a put option for shares of the Company’s common stock distributed from the plan. Shares are distributed from the Davey 401KSOP and ESOP Plan to former participants of the plan, their beneficiaries, donees or heirs (each, a “participant”). Since our common stock is not currently traded on an established securities market, if the owners of distributed shares desire to sell their shares, the Company is required to purchase the shares at fair value for two 60 -day periods after distribution of the shares from the Davey 401KSOP and ESOP. The fair value of distributed shares subject to the put option totaled $3,843 and $1,148 as of December 31, 2017 and December 31, 2016, respectively. The fair value of the shares held in the Davey 401KSOP and ESOP totaled $119,677 and $123,053 as of December 31, 2017 and December 31, 2016, respectively. Due to the Company’s obligation under the put option, the distributed shares subject to the put option and the shares held in the Davey 401KSOP and ESOP (collectively referred to as 401KSOP and ESOP related shares) are classified as temporary equity in the mezzanine section of the consolidated balance sheets and totaled $123,520 and $124,201 as of December 31, 2017 and December 31, 2016, respectively. Changes in the fair value of the Davey 401KSOP and ESOP Plan related shares are reflected in retained earnings while net share activity associated with the Davey 401KSOP and ESOP Plan related shares are first reflected in additional paid-in capital and then retained earnings if additional paid in-capital is insufficient. Total compensation for these plans, consisting primarily of the employer match, was $3,794 in 2017 , $3,661 in 2016 , and $3,373 in 2015 .

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Our shareholders approved the 2014 Omnibus Stock Plan (the “2014 Stock Plan”) at our annual meeting of shareholders on May 20, 2014. The 2014 Stock Plan replaced the expired 2004 Omnibus Stock Plan (the “2004 plan”) previously approved by the shareholders in 2004. The 2014 Stock Plan is administered by the Compensation Committee of the Board of Directors and will remain in effect for ten years. All directors of the Company and employees of the Company and its subsidiaries are eligible to participate in the 2014 Stock Plan. The 2014 Stock Plan (similar to the 2004 plan) continues the maintenance of the Employee Stock Purchase Plan, as well as provisions for the grant of stock options and other stock-based incentives. The 2014 Stock Plan provides for the grant of five percent of the number of the Company’s common shares outstanding as of the first day of each fiscal year plus the number of common shares that were available for grant of awards, but not granted, in prior years. In no event, however, may the number of common shares available for the grant of awards in any fiscal year exceed ten percent of the common shares outstanding as of the first day of that fiscal year. Common shares subject to an award that is forfeited, terminated, or canceled without having been exercised are generally added back to the number of shares available for grant under the 2014 Stock Plan. O. Stock-Based Compensation (continued) Stock-based compensation expense under all share-based payment plans—our Employee Stock Purchase Plan, stock option plans, stock-settled stock appreciation rights, and performance-based restricted stock units—included in the results of operations follows: Year Ended December 31, 2017 2016 2015 Compensation expense, all share-based payment plans $ 4,049 $ 2,811 $ 2,327 Income tax benefit 1,315 823 694 Stock-based compensation consisted of the following: Employee Stock Purchase Plan --Under the Employee Stock Purchase Plan, all full-time employees with one year of service are eligible to purchase, through payroll deduction, common shares. Employee purchases under the Employee Stock Purchase Plan are at 85% of the fair market value of the common shares--a 15% discount. Purchases under the plan, at 85% of the fair market value of the common shares, have been as follows: Year Ended December 31, 2017 2016 2015 Number of employees participating 2,297 1,952 1,750 Shares purchased during the year 335,040 297,262 251,558 Weighted-average per share purchase price paid $ 15.27 $ 14.17 $ 13.11 Cumulative shares purchased since 1982 18,386,370 18,051,330 17,754,068 Compensation costs are recognized as payroll deductions are made. The 15% discount of total shares purchased under the plan resulted in compensation cost recognized of $888 in 2017 , $727 in 2016 and $569 in 2015 . Stock Options Plan --The stock options outstanding were awarded under a graded vesting schedule, measured at fair value, and have a term of ten years. Compensation costs for stock options are recognized over the requisite service period on the straight-line recognition method. Compensation cost recognized for stock options was $705 in 2017 , $596 in 2016 and $494 in 2015 . Stock-Settled Stock Appreciation Rights --During the year ended December 31, 2017 , the Compensation Committee of the Board of Directors awarded 152,000 Stock-Settled Stock Appreciation Rights (“SSARs”) to certain management employees which vest ratably over five years. A stock-settled stock appreciation right is an award that allows the recipient to receive common stock equal to the appreciation in the fair market value of our common stock between the date the award was granted and the conversion date of the shares vested. O. Stock-Based Compensation (continued) The following table summarizes the SSARs as of December 31, 2017 : Stock-Settled Stock Appreciation Rights Number of Rights Weighted- Average Award Date Value Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Unvested, January 1, 2017 743,662 $ 2.75 Granted 152,000 3.57 Forfeited (8,060 ) 3.09 Vested (439,422 ) 2.67 Unvested, December 31, 2017 448,180 $ 3.10 2.5 years $ 998 $ 8,202 Compensation costs for SSARs are determined using a fair-value method and amortized over the requisite service period. Compensation expense for SSARs totaled $1,035 in 2017 , $591 in 2016 and $489 in 2015 . Restricted Stock Units --During the year ended December 31, 2017 , the Compensation Committee of the Board of Directors awarded 68,086 performance-based restricted stock units ("PRSUs") to certain management employees and 12,264 restricted stock units ("RSUs") to nonemployee directors. The Compensation Committee made similar awards in prior periods. The awards vest over specified periods. The following table summarizes restricted stock units as of December 31, 2017 : Restricted Stock Units Number of Stock Units Weighted- Average Grant Date Value Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Unvested, January 1, 2017 304,958 $ 13.22 Granted 80,350 17.01 Forfeited — — Vested (94,642 ) 12.76 Unvested, December 31, 2017 290,666 $ 14.41 2.2 years $ 2,063 $ 5,319 Employee PRSUs 253,242 $ 14.20 2.5 years $ 1,773 $ 4,634 Nonemployee Director RSUs 37,424 $ 15.85 1.4 years $ 290 $ 685 Compensation cost for awards is determined using a fair-value method, amortized over the requisite service period. “Intrinsic value” is defined as the amount by which the fair market value of a common share of stock exceeds the exercise price of a performance-based restricted stock unit. Compensation expense on restricted stock awards totaled $1,421 in 2017 , $897 in 2016 and $775 in 2015 . The fair value of each award was estimated on the date of grant using a binomial option-pricing model. The binomial model considers a range of assumptions related to volatility, risk-free interest rate and employee exercise behavior. Expected volatilities utilized in the binomial model are based on historical volatility of our share prices and other factors. Similarly, the dividend yield is based on historical experience and expected future changes. The binomial model also incorporates exercise and forfeiture assumptions based on an analysis of historical data. The expected life of the stock-based awards is derived from the output of the binomial model and represents the period of time that awards granted are expected to be outstanding. O. Stock-Based Compensation (continued) The fair values of stock-based awards granted were estimated at the dates of grant with the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Volatility rate 10.3 % 10.6 % 10.9 % Risk-free interest rate 2.2 % 1.8 % 2.1 % Expected dividend yield .7 % .7 % .7 % Expected life of awards (years) 8.9 9.5 9.3 General Stock Option Information --The following table summarizes activity under the stock option plans for the year ended December 31, 2017 : Stock Options Number of Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Outstanding, January 1, 2017 1,599,296 $ 12.49 Granted 148,500 17.60 Exercised (138,107 ) 11.30 Forfeited (81,074 ) 13.34 Outstanding, December 31, 2017 1,528,615 $ 13.05 6.2 years $ 1,534 $ 8,025 Exercisable, December 31, 2017 800,615 $ 11.14 4.8 years $ 5,660 “Intrinsic value” is defined as the amount by which the market price of a common share of stock exceeds the exercise price of an option. Information regarding the stock options outstanding at December 31, 2017 is summarized below: Stock Options Exercise Price Number Outstanding Weighted-Average Remaining Contractual Life Weighted- Average Exercise Price Number Exercisable Weighted- Average Exercise Price Employee options: $ 8.00 144,948 1.8 years $ 8.00 144,948 $ 8.00 8.30 167,098 2.8 years 8.30 167,098 8.30 11.60 296,047 5.5 years 11.60 216,647 11.60 13.20 303,122 6.5 years 13.20 156,322 13.20 15.05 235,000 7.5 years 15.05 74,200 15.05 16.35 245,400 8.5 years 16.35 41,400 16.35 17.60 137,000 9.5 years 17.60 — 17.60 1,528,615 6.2 years $ 13.05 800,615 $ 11.14 O. Stock-Based Compensation (continued) We issue common shares from treasury upon the exercise of stock options, stock-settled stock appreciation rights, performance-based restricted stock units or purchases under the Employee Stock Purchase Plan. Tax Benefits of Stock-Based Compensation-- Our total income tax benefit from share-based awards--as recognized in our consolidated statement of operations--for the last three years was: $1,315 in 2017 , $823 in 2016 , and $694 in 2015 . Tax benefits for share-based awards are accrued as stock compensation expense and recognized in our consolidated statement of operations. Tax benefits on share-based awards are realized when: (a) stock-settled stock appreciation rights are exercised; (b) performance-based restricted stock units vest; and (c) stock options are exercised. When actual tax benefits realized exceed the tax benefits accrued for share-based awards, we realize an excess tax benefit. We had excess tax benefits of: $691 in 2017 , $1,113 in 2016 , and $352 in 2015 .

Defined Benefit Pension Plans

Defined Benefit Pension Plans	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Pension Plans	Defined Benefit Pension Plans We have defined benefit pension plans covering certain current and retired U.S. employees. Plans include: (i) the Employee Retirement Plan (“ERP”) for employees hired prior to January 1, 2009; (ii) a Supplemental Executive Retirement Plan (“SERP”) for which future benefit accruals were frozen effective at the end of the second quarter 2015; and (iii) a Benefit Restoration Pension Plan (“Restoration Plan”) for certain key employees hired prior to January 1, 2009. Both the SERP and the Restoration Plan are defined benefit plans under which nonqualifed supplemental pension benefits will be paid in addition to amounts paid under our qualified retirement defined benefit pension plans, which are subject to Internal Revenue Service limitations on covered compensation. Effective December 31, 2008, enhanced benefits were implemented to our defined contribution savings plan--The Davey 401KSOP and ESOP--at which time, the Board of Directors approved an amendment to freeze the ERP and the Restoration Plan. The ERP was closed to new participants after December 2008. In connection with the freeze of the ERP, the Restoration Plan and the SERP, (a) benefits currently being paid to retirees continue and (b) benefits accrued through December 31, 2008 for employees covered by the ERP were not affected. All ERP, Restoration Plan and SERP balances remain intact and participant account balances, as well as service credits for vesting and retirement eligibility, remain intact and continue in accordance with the terms of the plans. Only future accruals were eliminated with: (i) the 2008 freeze of the ERP and Restoration Plan and (ii) the 2015 freeze of the SERP. During the first quarter of 2016, the Company terminated the plan for bargaining employees not covered by union pension plans ("SPP") for which future benefit accruals were frozen effective December 31, 2013. We purchased a guaranteed group annuity contract from a third-party insurance company, which unconditionally and irrevocably guarantees the full payment of all annuity payments to the 94 participants. In connection with the plan termination, we made cash contributions of $522 to fully fund the SPP obligation and recorded a settlement charge of $453 . P. Defined Benefit Pension Plans (continued) The change in benefit obligations and the fair value of plans assets follows: December 31, 2017 2016 Change in benefit obligation Projected benefit obligation at beginning of year $ 24,833 $ 27,228 Service cost 530 370 Interest cost 1,002 1,243 Actuarial (gains)/losses 1,865 703 Amendments — 341 Settlements (8,400 ) (4,873 ) Benefits paid (427 ) (179 ) Projected benefit obligation at end of year $ 19,403 $ 24,833 Accumulated benefit obligation at end of year $ 19,403 $ 24,833 December 31, 2017 2016 Change in fair value of plan assets Fair value of plan assets at beginning of year $ 11,509 $ 15,216 Actual return on plan assets 845 400 Plan expenses, including PBGC premiums (513 ) (727 ) Employer contributions 4,091 1,672 Settlements (8,400 ) (4,873 ) Benefits paid (427 ) (179 ) Fair value of plan assets at end of year $ 7,105 $ 11,509 The settlements in the change in benefit obligation and in the change in fair value of plan assets arise from: (i) purchase during the fourth quarter 2017 of a guaranteed group annuity contract from a third-party insurance company which unconditionally and irrevocably guarantees the full payment of all annuity payments to a combination of participants currently receiving benefits or entitled to future benefits from the ERP plan; (ii) termination of the SPP plan during the first quarter of 2016; and (iii) lump sum offering to 224 participants in our ERP plan during the fourth quarter of 2016. December 31, 2017 2016 Funded status of the plans Fair value of plan assets $ 7,105 $ 11,509 Projected benefit obligation 19,403 24,833 Funded status of the plans $ (12,298 ) $ (13,324 ) P. Defined Benefit Pension Plans (continued) December 31, 2017 2016 Amounts reported in the consolidated balance sheets Current liability $ (175 ) $ (83 ) Noncurrent liability (12,123 ) (13,241 ) Funded status of the plans $ (12,298 ) $ (13,324 ) Amounts included in accumulated other comprehensive income (loss), related to our defined benefit pension plans follow: At December 31, 2017 At December 31, 2016 Pretax Net of Tax Pretax Net of Tax Amounts reported in accumulated other comprehensive income Unrecognized net actuarial loss $ 8,086 $ 4,919 $ 10,675 $ 6,456 Unrecognized prior service cost 278 169 341 206 $ 8,364 $ 5,088 $ 11,016 $ 6,662 To the extent actuarial losses exceed the greater of 10% of the projected benefit obligation or market-related value of plan assets, the unrecognized actuarial losses will be amortized straight-line on a plan-by-plan basis, over the remaining expected future working lifetime of active participants, except for the SERP, which, after the plan freeze, is being amortized based on the remaining life expectancy of plan participants. The total amount of unrecognized prior service cost was amortized straight-line on a plan-by-plan basis. The total amortization associated with these amounts that is expected to be recognized in net periodic benefit expense for 2018 follows: Year ending December 31, 2018 Pretax Net of Tax Amortization of Costs Expected to be Recognized Next Year Unrecognized net actuarial loss $ 727 $ 436 Unrecognized prior service cost 64 38 $ 791 $ 474 The aggregate projected benefit obligation, accumulated benefit obligation and fair value of plan assets for plans in which the fair value of plan assets is less than either the projected benefit obligation or accumulated benefit obligation follow: December 31, 2017 2016 For pension plans with accumulated benefit obligations in excess of plan assets Projected benefit obligation $ 19,403 $ 24,833 Accumulated benefit obligation 19,403 24,833 Fair value of plan assets 7,105 11,509 P. Defined Benefit Pension Plans (continued) The actuarial assumptions follow. The discount rates were used to measure the year-end benefit obligation and compute pension expense for the subsequent year. December 31, 2017 2016 2015 Actuarial assumptions Discount rate 3.70 % 4.20 % 4.70 % Expected long-term rate of return on plan assets 2.50 5.00 7.25 Net periodic benefit expense (income) associated with the defined benefit pension plans included the following components: Year Ended December 31, 2017 2016 2015 Components of pension expense (income) Service costs--increase in benefit obligation earned $ 530 $ 370 $ 35 Interest cost on projected benefit obligation 1,002 1,243 1,486 Expected return on plan assets (638 ) (1,044 ) (1,576 ) Curtailment loss — — 49 Settlement loss 3,849 2,346 2,915 Amortization of net actuarial loss 909 951 1,400 Amortization of prior service cost 64 — 6 Net pension expense of defined benefit pension plans $ 5,716 $ 3,866 $ 4,315 Investment Strategy and Risk Management for Plan Assets-- Our investment strategy is to manage the plan assets in order to pay retirement benefits to plan participants while minimizing our cash contributions over the life of the plans. This is accomplished by maintaining liquidity and preserving principal through diversification in high-quality investments through the use of investment managers and mutual funds. Performance of all investment managers and mutual funds is monitored quarterly and evaluated over rolling three -to- five year periods. In December 2017, we revised our investment policy to reallocate 100% of our plan assets into the fixed income and cash asset class from the prior target allocations of: (a) equities of a minimum 20% to a maximum of 40% ; (b) fixed income and cash of a minimum 50% to a maximum of 70% ; and, (c) alternative investments of a minimum of zero to a maximum of 15% . The purpose of the fixed income asset class is to provide a deflation hedge, to reduce the overall volatility of plan assets and to produce current income in support of the needs of the plan. Fixed income assets can be invested in U.S. government and prime money market funds, U.S. Treasuries, insured certificates of deposit and U.S. investment grade corporates of at least "A" or better quality and other high quality debt securities. Other than investments in U.S. government or government agencies, no single debt issue will be allowed to exceed 5% market value of the debt portfolio. Short-selling, securities lending, financial futures, margins, options, and derivatives are not used. Investments in nonmarketable securities, commodities, or direct ownership of real estate are prohibited. Rate-of-return-on-assets assumptions are made based on the mix of assets according to our investment policy. Given the reallocation of plan assets into the fixed income and cash asset class, the overall expected long-term rate-of-return-on-plan assets net of investment manager fees as at December 31, 2017 , was 2.50% . P. Defined Benefit Pension Plans (continued) Plan Assets --The fair values of our pension plan assets at December 31, 2017 by asset category, using the three-level hierarchy of fair value inputs, were as follows: Fair Value Measurements at December 31, 2017 Using: Description Total Carrying Value at December 31, 2017 Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Asset Category Money market funds (a) $ 897 $ — $ 897 $ — U.S. large-cap equities Growth 576 576 — — Value 542 542 — — U.S. small/mid-cap equities Growth 246 246 — — Value 247 247 — — International equities Growth 376 376 — — Value 366 366 — — Fixed income 3,070 3,070 — — Multiclass world-allocation mutual funds 785 785 — — $ 7,105 $ 6,208 $ 897 $ — The fair values of our pension plan assets at December 31, 2016 by asset category, using the three-level hierarchy of fair value inputs, were as follows: Fair Value Measurements at December 31, 2016 Using: Description Total Carrying Value at December 31, 2016 Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Asset Category Money market funds (a) $ 2,882 $ — $ 2,882 $ — U.S. large-cap equities Growth 687 687 — — Value 729 729 — — U.S. small/mid-cap equities Growth 339 339 — — Value 339 339 — — International equities Growth 443 443 — — Value 514 514 — — Fixed income 4,669 4,669 — — Multiclass world-allocation mutual funds 907 907 — — $ 11,509 $ 8,627 $ 2,882 $ — P. Defined Benefit Pension Plans (continued) Within the pension plan asset categories, the Level 1 investments are publicly traded in active markets and are valued using the net asset value or closing price of the investment at the measurement date. Securities held by a money market fund are generally high quality and liquid; however, they are reflected as Level 2 because the inputs used to determine fair value are not quoted prices in an active market. Expected Benefit Plan Contributions --It is our practice to make contributions to comply with the minimum funding requirements of ERISA. In accordance with such practice, contributions totaling $638 are required for 2018; however, we may make additional discretionary contributions. Expected Benefit Plan Payments --The benefits, as of December 31, 2017 , expected to be paid to defined-benefit plan participants in each of the next five years, and in the aggregate for the five years thereafter, follow: Participants Benefits Estimated future payments Year ending December 31, 2018 $ 565 2019 675 2020 757 2021 809 2022 856 Years 2023 to 2027 4,835 Multiemployer Defined Benefit Pension Plans --In providing services to our Utility Services customers, we contribute to multiemployer defined benefit pension plans under the terms of collective-bargaining agreements that cover certain of our union-represented employees. These plans generally provide retirement benefits to participants based on their service to contributing employers. We do not administer these multiemployer plans. In general, these plans are managed by a board of trustees with the unions appointing certain trustees and other contributing employers of the plan appointing certain members. We generally are not represented on the board of trustees. The risks of participating in these multiemployer plans are different from single-employer plans in that: (a) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers; (b) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be assumed by the remaining participating employers; and, (c) if we choose to stop participating in a multiemployer plan, we may be required to pay the plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Our participation in the multiemployer defined benefit pension plans is summarized in the table below. The “EIN/Pension Plan Number” column provides the Employer Identification Number (“EIN”) and the three-digit plan number. The most recent Pension Protection Act of 2006 (the “PPA”) zone status is from the Form 5500, “Annual Return/Report of Employee Benefit Plan,” filed by the plan and certified by the plan's actuary. The PPA zone status describes plans that are underfunded. Among other factors, plans in the “critical” red zone are generally less than 65% funded; plans in the “endangered” yellow zone are less than 80% funded; and, plans in the “safe” green zone are at least 80% funded. P. Defined Benefit Pension Plans (continued) Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status FIP/RP Status Pending Implemented Davey Tree Contributions Surcharge Imposed Expiration Dates of Bargaining Agreement 2017 2016 2017 2016 2015 National Electric Benefit Fund 53-0181657/001 Green Green No $ 785 $ 712 $ 774 No Ranging from June 30, 2017 to December 31, 2018 Eighth District Electrical Pension Fund 84-6100393/001 Green Green No 102 90 119 No December 31, 2017 $ 887 $ 802 $ 893 We were not listed in the Form 5500 for either plan as having provided more than 5% of the total contributions. Both the National Electric Benefit Fund and the Eighth District Electrical Pension Fund are green zone status--safe--which represents at least 80% funded and does not require a “financial improvement plan” (“FIP”) or a “rehabilitation plan” (“RP”). We are party to nine collective-bargaining agreements with the National Electric Benefit Fund, with expiration dates ranging from June 30, 2017 to December 31, 2018, and one collective-bargaining agreement with Eighth District Electrical Pension Fund which expired on December 31, 2017. Expired agreements are currently being renegotiated.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the President of the United States (“U.S.”) signed into law the Tax Cuts and Jobs Act (the “Tax Reform Act”), which enacts significant changes to U.S. tax laws. Some of the provisions of the new tax law affecting corporations include, but are not limited to lowering the U.S. corporate income tax rate from 35% to 21% effective January 1, 2018, immediate expensing of certain qualified capital expenditures, implementing a territorial tax system and imposing a one-time transitional toll tax on deferred foreign earnings. As a result of the Tax Reform Act, the Company recorded the provisional tax effects, including a tax charge of $1.0 million due to the remeasurement of deferred tax assets and liabilities in the fourth quarter of 2017. The Company has also estimated a tax liability of $6.1 million due to the transition toll tax on the deemed repatriation of deferred foreign earnings of non-U.S. operations, which the Company believes will be fully offset by foreign tax credits. The final amounts recorded in subsequent financial statements may differ from these provisional amounts due to, among other things, additional analysis related to foreign deferred earnings, changes in interpretations of the Tax Reform Act and related assumptions of the Company and additional regulatory guidance that may be issued. On December 22, 2017, the Securities and Exchange Commission (“SEC”) issued Staff Accounting Bulletin 118 (“SAB 118”). This guidance allows registrants a “measurement period”, not to exceed one year from the date of enactment, to complete their accounting for the tax effects of the Tax Reform Act. SAB 118 further directs that during the measurement period, registrants who are able to make reasonable estimates for the tax effects of the Tax Reform Act should include those amounts in their financial statements as “provisional” amounts. Registrants should reflect adjustments over subsequent periods as they are able to refine their estimates and complete their accounting for the tax effects of the Tax Reform Act. The provisional amounts computed by the Company are expected to be finalized when the U.S. corporate income tax return for 2017 is filed in 2018, but in no event later than one year from the enactment date. Other provisions of the Tax Reform Act include a new minimum tax on certain foreign earnings (the Global Intangibles Low-taxed Income, or “GILTI”), a new tax on certain payments to foreign related parties (the Base Erosion Anti-Avoidance tax, or “BEAT”), a new incentive for Foreign-derived Intangibles Income (“FDII”), repealing the deduction for domestic production activities, changes to the limitation on the deductibility of certain executive compensation, and new limitations on the deductibility of interest expense. Generally, the tax effect of these other provisions will begin for the Company in the year ending December 31, 2018. Q. Income Taxes (continued) Income before income taxes was attributable to the following sources: Year Ended December 31, 2017 2016 2015 United States $ 38,800 $ 35,867 $ 32,807 Canada (806 ) 1,377 2,451 Total $ 37,994 $ 37,244 $ 35,258 The provision for income taxes follows: Year Ended December 31, 2017 2016 2015 Currently payable: Federal $ 9,914 $ 12,216 $ 13,337 State 2,469 2,286 2,487 Canadian (262 ) 398 611 Total current 12,121 14,900 16,435 Deferred taxes 3,753 60 (2,975 ) Total taxes on income $ 15,874 $ 14,960 $ 13,460 A reconciliation of the expected statutory U.S. federal rate to our actual effective income tax rate follows: Year Ended December 31, 2017 2016 2015 Statutory U.S. federal tax rate 35.0 % 35.0 % 35.0 % State income taxes, net of federal benefit 4.9 4.0 3.7 Effect of Canadian income taxes .3 (.2 ) (.5 ) Nondeductible expenses 2.2 2.2 2.3 ESOP dividend deduction (.6 ) (.7 ) (.8 ) Uncertain tax adjustments and audit settlement (.2 ) .2 1.5 Valuation allowance — — (2.2 ) Income tax reform 2.5 — — All other, net (2.3 ) (.3 ) (.8 ) Effective income tax rate 41.8 % 40.2 % 38.2 % Deferred income taxes reflect the tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A valuation allowance is recorded when it is more-likely-than-not that an income tax benefit will not be realized. Q. Income Taxes (continued) Significant components of our noncurrent net deferred tax assets and liabilities at December 31, were as follows: December 31, 2017 2016 Deferred tax assets: Self-insurance accruals $ 14,186 $ 21,967 Accrued compensated absences 1,747 3,540 Accrued expenses and other liabilities 798 1,394 Accrued stock compensation 1,571 2,502 Defined benefit pension plans 2,289 4,019 Foreign tax credit carryforward 605 575 Other future deductible amounts, net 3,661 4,213 24,857 38,210 Deferred tax liabilities: Intangibles 969 297 Prepaid expenses 2,300 3,510 Property and equipment 16,773 23,274 20,042 27,081 Net deferred tax assets--noncurrent $ 4,815 $ 11,129 We treat all of our Canadian subsidiary earnings through December 31, 2017 as permanently reinvested and have not provided any U.S. federal or state tax thereon. As of December 31, 2017 , approximately $30,329 of undistributed earnings attributable to our Canadian operations was considered to be indefinitely invested. Presently, our intention is to reinvest the earnings permanently. If, in the future, these earnings are distributed to the U.S. in the form of dividends or otherwise, or if the Company determines such earnings will be remitted in the foreseeable future, the Company would be subject to Canadian withholding taxes. It is not practicable to estimate the amount of taxes that would be payable upon remittance of these earnings given the various tax planning alternatives that we could employ should we decide to repatriate those earnings. As of December 31, 2015, we released a valuation allowance that had been recorded in prior years related to the foreign tax credit carryforward that arose in 2010--wherein we repatriated earnings in 2010 of our Canadian operations due to capital in Canada in excess of current and future projected needs. Management presently believes that it is more-likely-than-not that the deferred tax asset, related to the foreign tax credits that expires in 2020 and 2027, will be realized. The criteria considered in making the determination included the ability to utilize tax-planning strategies, historical and projected operating results, and the period of time over which the foreign tax credit can be utilized. The amount of income taxes that we pay is subject to audit by U.S. federal, state, local and Canadian tax authorities, which may result in proposed assessments. Our estimate for the potential outcome for any uncertain tax issue is highly judgmental. Uncertain tax positions are recognized only if they are more-likely-than-not to be upheld during examination based on their technical merits. The measurement of the uncertain tax position is based on the largest benefit amount that is more-likely-than-not (determined on a cumulative probability basis) to be realized upon settlement of the matter. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when we determine the liabilities are no longer necessary. If the estimate of tax liabilities proves to be less than the ultimate settlement, a further charge to expense may result. Q. Income Taxes (continued) The balance of unrecognized benefits and the amount of related interest and penalties at December 31, were as follows: December 31, 2017 2016 Unrecognized tax benefits $ 2,581 $ 2,532 Portion, if recognized, would reduce tax expense and effective tax rate 1,948 2,053 Accrued interest on unrecognized tax benefits 128 107 We recognize interest accrued related to unrecognized tax benefits in income tax expense. Penalties, if incurred, would be recognized as a component of income tax expense. The Company is routinely under audit by U.S. federal, state, local and Canadian authorities in the area of income tax. These audits include questioning the timing and the amount of income and deductions and the allocation of income and deductions among various tax jurisdictions. During the fourth quarter 2017, the U.S. Internal Revenue Service initiated an audit of the Company's U.S. income tax returns for 2015. With the exception of U.S. state jurisdictions, the Company is no longer subject to examination by tax authorities for the years through 2013. As of December 31, 2017 , we believe it is reasonably possible that the total amount of unrecognized tax benefits will not significantly increase or decrease. The changes in our unrecognized tax benefits are summarized in the table below: Year Ended December 31, 2017 2016 2015 Balance, beginning of year $ 2,532 $ 2,557 $ 1,949 Additions based on tax positions related to the current year 650 402 642 Additions for tax positions of prior years (21 ) 51 52 Reductions for tax positions of prior years — (39 ) (63 ) Lapses in statutes of limitations (580 ) (439 ) (23 ) Balance, end of year $ 2,581 $ 2,532 $ 2,557

Earnings Per Share Information

Earnings Per Share Information	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share Information	Earnings Per Share Information Earnings per share is computed as follows (prior periods have been adjusted for the two-for-one stock split of our common shares effective June 1, 2017): Year Ended December 31, 2017 2016 2015 Income available to common shareholders: Net income $ 22,120 $ 22,284 $ 21,798 Weighted-average shares: Basic: Outstanding 24,793,086 25,378,600 26,058,736 Partially-paid share subscriptions 764,382 833,440 872,162 Basic weighted-average shares 25,557,468 26,212,040 26,930,898 Diluted: Basic from above 25,557,468 26,212,040 26,930,898 Incremental shares from assumed: Exercise of stock subscription purchase rights 146,453 142,746 135,428 Exercise of stock options and awards 993,141 892,568 888,254 Diluted weighted-average shares 26,697,062 27,247,354 27,954,580 Share data: Earnings per share--basic $ .87 $ .85 $ .81 Earnings per share--diluted $ .83 $ .82 $ .78

Operations by Business Segment

Operations by Business Segment and Geographic Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Operations by Business Segment and Geographic Information	Operations by Business Segment and Geographic Information We provide a wide range of arboricultural, horticultural, environmental and consulting services to residential, utility, commercial and government entities throughout the United States and Canada. We have two reportable operating segments organized by type or class of customer: Residential and Commercial, and Utility. Residential and Commercial --Residential and Commercial provides services to our residential and commercial customers including: the treatment, preservation, maintenance, removal and planting of trees, shrubs and other plant life; the practice of landscaping, grounds maintenance, tree surgery, tree feeding and tree spraying; the application of fertilizer, herbicides and insecticides; and, natural resource management and consulting, forestry research and development, and environmental planning. Utility --Utility is principally engaged in providing services to our utility customers--investor-owned, municipal utilities, and rural electric cooperatives--including: the practice of line-clearing and vegetation management around power lines, rights-of-way and chemical brush control; and, natural resource management and consulting, forestry research and development and environmental planning. All other operating activities, including research, technical support and laboratory diagnostic facilities, are included in “All Other.” 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. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies except that (a) we compute and recognize depreciation expense for our segments only by the straight-line method and (b) state income taxes are allocated to the segments. Corporate expenses are substantially allocated among the operating segments, but the nature of expenses allocated may differ from year-to-year. There are no intersegment revenues. S. Operations by Business Segment and Geographic Information (continued) Segment assets are those generated or directly used by each segment, and include accounts receivable, operating supplies, and property and equipment. Information on reportable segments and reconciliation to the consolidated financial statements follows: Utility Services Residential Commercial Services All Other Reconciling Adjustments Consolidated Fiscal Year 2017 Revenues $ 466,727 $ 446,028 $ 3,203 $ — $ 915,958 Income (loss) from operations 18,223 41,158 (2,634 ) (9,742 ) (a) 47,005 Interest expense (4,886 ) (4,886 ) Interest income 292 292 Other income (expense), net (4,417 ) (4,417 ) Income before income taxes $ 37,994 Depreciation $ 27,928 $ 19,384 $ — $ 3,390 (b) $ 50,702 Amortization 122 2,240 — 22 2,384 Capital expenditures 26,910 23,199 — 6,991 57,100 Segment assets, total 189,662 197,698 — 85,775 (c) 473,135 Fiscal Year 2016 Revenues $ 433,379 $ 410,878 $ 1,421 $ — $ 845,678 Income (loss) from operations 19,256 36,640 (4,318 ) (6,207 ) (a) 45,371 Interest expense (4,393 ) (4,393 ) Interest income 255 255 Other income (expense), net (3,989 ) (3,989 ) Income before income taxes $ 37,244 Depreciation $ 26,855 $ 17,198 $ — $ 3,231 (b) $ 47,284 Amortization 135 2,136 — 35 2,306 Capital expenditures 28,660 21,819 — 6,167 56,646 Segment assets, total 171,220 166,858 — 85,861 (c) 423,939 Fiscal Year 2015 Revenues $ 433,117 $ 386,327 $ 2,460 $ — $ 821,904 Income (loss) from operations 24,273 35,271 (5,368 ) (10,068 ) (a) 44,108 Interest expense (3,355 ) (3,355 ) Interest income 249 249 Other income (expense), net (5,744 ) (5,744 ) Income before income taxes $ 35,258 Depreciation $ 25,466 $ 15,592 $ — $ 3,619 (b) $ 44,677 Amortization 144 2,062 — 8 2,214 Capital expenditures 26,853 22,853 — 6,341 56,047 Segment assets, total 145,306 162,679 — 85,601 (c) 393,586 S. Operations by Business Segment and Geographic Information (continued) Reconciling adjustments from segment reporting to consolidated external financial reporting include unallocated corporate items: (a) Reconciling adjustments from segment reporting to consolidated external financial reporting include reclassification of depreciation expense and allocation of corporate expenses. (b) Adjustments to declining-balance method depreciation expense from straight-line method and depreciation and amortization of corporate assets. (c) Corporate assets include cash, prepaid expenses, corporate facilities, enterprise-wide information systems and other nonoperating assets. Geographic Information -- The following presents revenues and long-lived assets by geographic territory: Year Ended December 31, 2017 2016 2015 Revenues United States $ 847,540 $ 775,870 $ 749,896 Canada 68,418 69,808 72,008 $ 915,958 $ 845,678 $ 821,904 December 31, 2017 2016 2015 Long-lived assets, net United States $ 242,118 $ 224,727 $ 213,323 Canada 21,893 20,439 19,329 $ 264,011 $ 245,166 $ 232,652

Fair Value Measurements and Fin

Fair Value Measurements and Financial Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements and Financial Instruments	Fair Value Measurements and Financial Instruments Financial Accounting Standards Board Accounting Standard Codification 820, “Fair Value of Measurements and Disclosures (“Topic 820”)” defines fair value based on the price that would be received to sell an asset or the exit price that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. Market participants are defined as buyers or sellers in the principal or most advantageous market for the asset or liability that are independent of the reporting entity, knowledgeable and able and willing to transact for the asset or liability. Valuation Hierarchy --Topic 820 establishes a fair value hierarchy that prioritizes observable and unobservable inputs used to measure fair value. The hierarchy prioritizes the inputs into three broad levels: Level 1 inputs are quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. Level 2 inputs are observable inputs other than prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated with observable market data. Level 3 inputs are unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. T. Fair Value Measurements and Financial Instruments (continued) Our assets and liabilities measured at fair value on a recurring basis at December 31, 2017 and December 31, 2016 , were as follows: Fair Value Measurements at December 31, 2017 Using: Total Carrying Value at Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Description December 31, 2017 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 19,422 $ 19,422 $ — $ — Defined benefit pension plan assets 7,105 6,208 897 — Liabilities: Deferred compensation $ 2,146 $ — $ 2,146 $ — Fair Value Measurements at December 31, 2016 Using: Total Carrying Value at Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Description December 31, 2016 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 15,492 $ 15,492 $ — $ — Defined benefit pension plan assets 11,509 8,627 2.882 — Liabilities: Deferred compensation $ 1,837 $ — $ 1,837 $ — The estimated fair value of the deferred compensation--classified as Level 2--is based on the value of the Company's common shares, determined by independent valuation. T. Fair Value Measurements and Financial Instruments (continued) Fair Value of Financial Instruments --The fair values of our current financial assets and current liabilities, including cash, accounts receivable, accounts payable, and accrued expenses among others, approximate their reported carrying values because of their short-term nature. The assets invested for self-insurance are money market funds--classified as Level 1--based on quoted market prices of the identical underlying securities in active markets. Financial instruments classified as noncurrent liabilities and their carrying values and fair values were as follows: December 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value Revolving credit facility, noncurrent $ 100,000 $ 100,000 $ 67,000 $ 67,000 Senior unsecured notes 12,000 12,389 18,000 18,509 Term loans, noncurrent 7,935 10,038 7,623 9,854 Total $ 119,935 $ 122,427 $ 92,623 $ 95,363 The carrying value of our revolving credit facility approximates fair value--classified as Level 2--as the interest rates on the amounts outstanding are variable. The fair value of our senior unsecured notes and term loans--classified as Level 2--is determined based on expected future weighted-average interest rates with the same remaining maturities. Market Risk-- In the normal course of business, we are exposed to market risk related to changes in foreign currency exchange rates, changes in interest rates and changes in fuel prices. We do not hold or issue derivative financial instruments for trading or speculative purposes. In prior years, we have used derivative financial instruments to manage risk, in part, associated with changes in interest rates and changes in fuel prices. Presently, we are not engaged in any hedging or derivative activities.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Letters of Credit At December 31, 2017 , we were contingently liable to our principal banks in the amount of $63,242 for letters of credit outstanding primarily related to insurance coverage. Surety Bonds In certain circumstances, we have performance obligations that are supported by surety bonds in connection with our contractual commitments. Litigation We are party to a number of lawsuits, threatened lawsuits and other claims arising out of the normal course of business. On a quarterly basis, we assess our liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. Where it is probable that we will incur a loss and the amount of the loss can be reasonably estimated, we record a liability in our consolidated financial statements. These legal reserves may be increased or decreased to reflect any relevant developments on a quarterly basis. Where a loss is not probable or the amount of the loss is not estimable, we do not accrue legal reserves, consistent with applicable accounting guidance. Based on information currently available to us, advice of counsel, and available insurance coverage, we believe that our established reserves are adequate and the liabilities arising from the legal proceedings will not have a material adverse effect on our consolidated financial condition. We note, however, that in light of the inherent uncertainty in legal proceedings there can be no assurance that the ultimate resolution of a matter will not exceed established reserves. As a result, the outcome of a particular matter or a combination of matters may be material to our results of operations for a particular period, depending upon the size of the loss or our income for that particular period. U. Commitments and Contingencies (continued) In November 2017, a suit was filed against Davey Tree, its subsidiary, Wolf Tree, Inc., a former Davey employee, two Wolf employees, and a former Wolf employee alleging various acts of negligence and seeking compensatory and punitive damages for wrongful death and assault and battery of the plaintiff’s husband, a Wolf Tree employee in Savannah, Georgia, who was killed in August 2017. The Company has denied all liability and is vigorously defending the action. It also has retained separate counsel for three of the individual defendants, each of whom has denied all liability and also is vigorously defending the action.

Quarterly Results of Operations

Quarterly Results of Operations	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited)	Quarterly Results of Operations (Unaudited) The following is a summary of the results of operations for each quarter of 2017 and 2016 . We have given retroactive consideration to the two-for-one stock split of our common shares effective June 1, 2017. Fiscal 2017, Three Months Ended Apr 1 Jul 1 Sep 30 Dec 31 Revenues $ 192,813 $ 245,037 $ 249,588 $ 228,520 Gross profit (revenues less costs and expenses, operating) 59,154 93,512 91,973 83,986 Income (loss) from operations (4,342 ) 25,312 18,701 7,334 Net income (loss) (3,887 ) 14,223 10,237 1,547 Net income (loss) per share -- Basic $ (.15 ) $ .57 $ .41 $ .04 Net income (loss) per share -- Diluted $ (.15 ) $ .55 $ .39 $ .04 ESOT valuation per share $ 17.60 $ 17.60 $ 18.30 $ 19.10 Fiscal 2016, Three Months Ended Apr 2 Jul 2 Oct 1 Dec 31 Revenues $ 180,833 $ 224,763 $ 223,719 $ 216,363 Gross profit (revenues less costs and expenses, operating) 57,660 87,631 81,386 77,515 Income (loss) from operations (5,120 ) 24,286 15,042 11,163 Net income (loss) (4,188 ) 13,309 8,141 5,022 Net income (loss) per share -- Basic $ (.16 ) $ .52 $ .32 $ .17 Net income (loss) per share -- Diluted $ (.16 ) $ .50 $ .31 $ .17 ESOT valuation per share $ 16.35 $ 16.35 $ 16.95 $ 17.60 Fourth quarters 2017 and 2016 include a decrease in casualty insurance expense that had the effect of increasing the fourth quarter gross profit for 2017 and 2016 by approximately $2,735 and $2,810, respectively.

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of consolidation and basis of presentation [Text Block]	Principles of Consolidation and Basis of Presentation --The consolidated financial statements include the accounts of Davey Tree and our wholly-owned subsidiaries and were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as codified in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC"). Intercompany accounts and transactions have been eliminated in consolidation. Per Common Share Information --We have given retroactive consideration to the two -for-one stock split of our common shares effective June 1, 2017 including all common share and per share data.
Use of estimates in financial statement preparation [Policy Text Block]	Use of Estimates in Financial Statement Preparation --The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts. Estimates are used for, but not limited to, accounts receivable valuation, depreciable lives of fixed assets, self-insurance accruals, and revenue recognition. Actual results could differ from those estimates.
Property and equipment [Policy Text Block]	Property and Equipment --Property and equipment are stated at cost. Repair and maintenance costs are expensed as incurred. Depreciation is computed for financial reporting purposes by the straight-line method for land improvements, building and leasehold improvements and by the declining-balance method for equipment, based on the estimated useful lives of the assets, as follows: Land improvements 5 to 20 years Buildings 5 to 30 years Equipment 3 to 10 years Leasehold improvements Shorter of lease term or estimated useful life; ranging from 5-to-20 years
Intangible assets [Policy Text Block]	Intangible Assets --Intangible assets with finite lives, primarily customer lists, noncompete agreements and tradenames, are amortized by the straight-line method based on their estimated useful lives, ranging from one-to-ten years.
Long-lived assets [Policy Text Block]	Long-Lived Assets --We assess potential impairment to our long-lived assets, other than goodwill, when there is evidence that events or changes in circumstances have made recovery of the asset’s carrying value unlikely and the carrying amount of the asset exceeds the estimated future undiscounted cash flow. In the event the assessment indicates that the carrying amounts B. Summary of Significant Accounting Policies (continued) may not be recoverable, an impairment loss would be recognized to reduce the asset’s carrying amount to its estimated fair value based on the present value of the estimated future cash flows.
Goodwill [Policy Text Block]	Goodwill --Goodwill is recorded when the cost of acquired businesses exceeds the fair value of the identified net assets acquired. Goodwill is not amortized, but tested for impairment annually or when events or circumstances indicate that impairment may have occurred. Annually, we perform the impairment tests for goodwill during the fourth quarter. Impairment of goodwill is tested at the reporting-unit level, which for us are also our business segments. Impairment of goodwill is tested by comparing the reporting unit’s carrying value, including goodwill, to the fair value of the reporting unit. The fair values of the reporting units are estimated using discounted projected cash flows. If the carrying value of the reporting unit exceeds its fair value, goodwill is considered impaired and an impairment loss should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. We conducted our annual impairment tests and determined that no impairment loss was required to be recognized in 2017 or for any prior periods. There were no events or circumstances from the date of our assessment through December 31, 2017 that would impact this conclusion.
Self-insurance accruals [Policy Text Block]	Self-Insurance Accruals --We are generally self-insured for losses and liabilities related primarily to workers’ compensation, vehicle liability and general liability claims. We use commercial insurance as a risk-reduction strategy to minimize catastrophic losses. Ultimate losses are accrued based upon estimates of the aggregate liability for claims incurred using certain actuarial assumptions followed in the insurance industry and based on Company-specific experience. Our self-insurance accruals include claims for which the ultimate losses will develop over a period of years. Accordingly, our estimates of ultimate losses can change as claims mature. Our accruals also are affected by changes in the number of new claims incurred and claim severity. The methods for estimating the ultimate losses and the total cost of claims were determined by third-party consulting actuaries; the resulting accruals are reviewed by management, and any adjustments arising from changes in estimates are reflected in income. The workers' compensation accruals are discounted as the amount and timing of cash payments related to those accruals are reliably determinable given the nature of workers' compensation benefits and the level of historical claim volume to support the actuarial assumptions and judgments used to derive the expected loss payment pattern. The workers' compensation accruals are discounted using an interest rate that approximates the long-term investment yields over the expected payment pattern of unpaid losses. Our self-insurance accruals are based on estimates and, while we believe that the amounts accrued are adequate and not excessive, the ultimate claims may be in excess of or less than the amounts provided.
Stock-based compensation [Policy Text Block]	Stock-Based Compensation -- Stock-based compensation cost for all share-based payment plans is measured at fair value on the date of grant and recognized over the employee service period on the straight-line recognition method for awards expected to vest. The fair value of all stock-based payment plans—stock option plans, stock-settled stock appreciation rights, and performance-based restricted stock units as well as our Employee Stock Purchase Plan—is determined by the number of awards granted and the price of our common stock. The fair value of each award is estimated on the date of grant using a binomial option-pricing model. The binomial model considers a range of assumptions related to volatility, risk-free interest rate and employee exercise behavior. Expected volatilities utilized in the binomial model are based on historical volatility of our share prices and other factors. Similarly, the dividend yield is based on historical experience and expected future changes. The binomial model also incorporates exercise assumptions based on an analysis of historical data. The expected life of the stock-based awards is derived from the output of the binomial model and represents the period of time that awards granted are expected to be outstanding.
Defined benefit pension plans [Policy Text Block]	Defined Benefit Pension Plans --We record annual expenses relating to our defined benefit pension plans based on calculations that include various actuarial assumptions, including discount rates and expected long-term rates of return on plan assets. Actuarial assumptions are reviewed annually with modifications made to the assumptions, if necessary, based on current rates and trends. The effects of the actuarial gains or losses are amortized over future service periods. The funded status (that is, the projected benefit obligation less the fair value of plan assets) for each plan is reported in our balance sheet B. Summary of Significant Accounting Policies (continued) using a December 31 measurement date. Changes in the funded status of the plans are recognized in the year in which the changes occur and reported in comprehensive income (loss).
Income taxes [Policy Text Block]	Income Taxes --We compute taxes on income in accordance with the tax rules and regulations where the income is earned. The income tax rates imposed by these taxing authorities vary. Taxable income may differ from pretax income for financial reporting purposes. We compute and recognize deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax bases of our assets and liabilities. Changes in tax rates and laws are reflected in income in the period when such changes are enacted. We account for uncertain tax positions by recognizing the financial statement effects of a tax position only when, based upon the technical merits, it is more-likely-than-not that the position will be sustained upon examination.
Earnings per share [Policy Text Block]	Earnings Per Share --Basic earnings per share is determined by dividing the income available to common shareholders by the weighted-average number of common shares outstanding. Diluted earnings per share is computed similarly to basic earnings per share except that the weighted-average number of shares is increased to include the effect of stock awards that were granted and outstanding during the period.
Revenue recognition [Policy Text Block]	Revenue Recognition --Revenues from residential and commercial services are recognized as the services are provided and amounts are determined to be collectible. Revenues from contractual arrangements, primarily with utility services customers, are recognized based on costs incurred to total estimated contract costs. During the performance of such contracts, estimated final contract prices and costs are periodically reviewed and revisions are made, as required, to the revenue recognized. On cost-plus-fee contracts, revenue is recognized to the extent of costs incurred plus a proportionate amount of fees earned, and on time-and-material contracts, revenue is recognized to the extent of billable rates times hours worked, plus material and other reimbursable costs incurred. Revisions arise in the normal course of providing services to utility services customers and generally relate to changes in contract specifications and cost allowability. Such revisions are recorded when realization is probable and can be reliably estimated.
Concentration of credit risk [Policy Text Block]	Concentration of Credit Risk --Credit risk represents the accounting loss that would be recognized if the counterparties failed to perform as contracted. The principal financial instruments subject to credit risk follow: Cash --To limit our exposure, we transact our business and maintain banking relationships with high credit-quality financial institutions. Accounts Receivable --Our residential and commercial customers are located geographically throughout the United States and Canada and, as to commercial customers, within differing industries; thus, minimizing credit risk. The credit exposure of utility services customers is directly affected by conditions within the utility industries as well as the financial condition of individual customers. One utility customer approximated 11% of revenues during 2017 , 12% in 2016 and 11% in 2015 . To reduce credit risk, we evaluate the credit of customers, but generally do not require advance payments or collateral. Exposure to losses on receivables is principally dependent on each customer’s financial condition.
Foreign currency translation and transactions [Policy Text Block]	Foreign Currency Translation and Transactions --Assets and liabilities of our Canadian operations are translated into U.S. dollars using year-end exchange rates, and revenues and expenses are translated using exchange rates as determined throughout the year. Gains or losses resulting from translation are included in the consolidated balance sheet, classified in shareholders’ equity as a separate component of accumulated other comprehensive income (loss). Gains or losses resulting from Canadian-dollar transactions with the Canadian operations are translated to U.S. dollars at the rates of exchange prevailing at the dates of the transactions. The effect of the transactions gain or loss is classified in the statement of operations as a component of other nonoperating income (expense), net.
Interst rate risk management [Policy Text Block]	Interest Rate Risk Management --We have entered into interest rate contracts, from time-to-time, with the objective of altering interest rate exposures related to variable rate debt. In the interest rate contracts, we have agreed with a financial
Comprehensive income (loss) [Policy Text Block]	Comprehensive Income (Loss) --Comprehensive income (loss) includes net income and other comprehensive income or loss. Other comprehensive income (loss) refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income but are excluded from net income as these amounts are recorded directly as an adjustment to shareholders’ equity, net of tax.
Business combinations [Policy Text Block]	The net assets of the businesses acquired are accounted for under the acquisition method and were recorded at their fair values at the dates of acquisition.
Commitments and contingencies [Policy Text Block]	We are party to a number of lawsuits, threatened lawsuits and other claims arising out of the normal course of business. On a quarterly basis, we assess our liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. Where it is probable that we will incur a loss and the amount of the loss can be reasonably estimated, we record a liability in our consolidated financial statements. These legal reserves may be increased or decreased to reflect any relevant developments on a quarterly basis. Where a loss is not probable or the amount of the loss is not estimable, we do not accrue legal reserves, consistent with applicable accounting guidance.

Summary of Significant Accoun33

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Property, plant and equipment [Table Text Block]	Depreciation is computed for financial reporting purposes by the straight-line method for land improvements, building and leasehold improvements and by the declining-balance method for equipment, based on the estimated useful lives of the assets, as follows: Land improvements 5 to 20 years Buildings 5 to 30 years Equipment 3 to 10 years Leasehold improvements Shorter of lease term or estimated useful life; ranging from 5-to-20 years

Accounts Receivable, Net and 34

Accounts Receivable, Net and Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts Receivable, Net and Supplemental Balance Sheet Information [Abstract]
Schedule of accounts receivable [Table Text Block]	Accounts receivable, net, consisted of the following: December 31, 2017 2016 Accounts receivable $ 143,244 $ 128,202 Receivables under contractual arrangements 29,895 21,541 173,139 149,743 Less allowances for doubtful accounts 4,468 3,609 $ 168,671 $ 146,134
Schedule of other current assets [Table Text Block]	The following items comprise the amounts included in the balance sheets: December 31, Other current assets 2017 2016 Refundable income taxes $ 587 $ 548 Other 784 1,315 Total $ 1,371 $ 1,863
Schedule of other assets, noncurrent [Table Text Block]	December 31, Other assets, noncurrent 2017 2016 Assets invested for self-insurance $ 19,422 $ 15,492 Investment--cost-method affiliate 1,218 1,168 Deferred income taxes 4,815 11,129 Other 3,701 3,565 Total $ 29,156 $ 31,354
Schedule of accrued expenses [Table Text Block]	December 31, Accrued expenses 2017 2016 Employee compensation $ 20,794 $ 18,438 Accrued compensated absences 9,267 9,215 Self-insured medical claims 3,193 2,961 Customer advances, deposits 1,672 2,997 Income taxes payable 3,443 953 Taxes, other than income 2,279 2,166 Other 2,168 929 Total $ 42,816 $ 37,659
Schedule of other liabilities, noncurrent [Table Text Block]	December 31, Other liabilities, noncurrent 2017 2016 Pension and retirement plans $ 14,759 $ 15,982 Other 5,207 4,837 Total $ 19,966 $ 20,819

Supplemental Operating Inform35

Supplemental Operating Information (Tables)	12 Months Ended
	Dec. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Schedule of other nonoperating income (Expense) [Table Text Block]	Other nonoperating (expense) income, net, included in the statements of operations follows: Year Ended December 31, 2017 2016 2015 Other nonoperating expense, net $ (4,417 ) $ (3,989 ) $ (5,744 )

Supplemental Cash Flow Inform36

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental cash flow information [Table Text Block]	Supplemental cash flow information follows: Year Ended December 31, Supplemental cash flow information 2017 2016 2015 Interest paid $ 5,096 $ 4,329 $ 3,386 Income taxes paid, net 10,005 10,578 16,679 Noncash transactions: Debt issued for purchases of businesses $ 3,099 $ 875 $ 1,500 Detail of acquisitions: Assets acquired: Receivables $ 1,753 $ — $ — Operating supplies — 157 — Prepaid expense 128 55 — Equipment 1,904 2,485 1,264 Deposits and other 52 — 11 Intangibles 4,296 1,374 1,464 Goodwill 5,131 817 1,410 Liabilities assumed (2,713 ) (216 ) — Debt issued for purchases of businesses (3,099 ) (875 ) (1,500 ) Cash paid $ 7,452 $ 3,797 $ 2,649

Identified Intangible Assets 37

Identified Intangible Assets and Goodwill, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of acquired finite-lived intangible assets by major class [Table Text Block]	The carrying amount of the identified intangibles and goodwill acquired in connection with our investments in businesses were as follows: Weighted-Average Amortization Period (Years) December 31, 2017 December 31, 2016 Carrying Amount Accumulated Amortization Carrying Amount Accumulated Amortization Amortized intangible assets: Customer lists/relationships 2.8 years $ 21,487 $ 16,846 $ 17,822 $ 15,171 Employment-related 2.2 years 7,333 6,624 7,032 6,386 Tradenames 2.9 years 5,978 5,134 5,634 4,860 Total 34,798 $ 28,604 30,488 $ 26,417 Less accumulated amortization 28,604 26,417 Identified intangibles, net 6,194 4,071 Unamortized intangible assets: Goodwill Not amortized 35,477 30,305 $ 41,671 $ 34,376
Schedule of goodwill [Table Text Block]	The changes in the carrying amounts of goodwill, by segment, for the year ended December 31, 2017 follow: Balance at January 1, 2017 Acquisitions Translation and Other Adjustments Balance at December 31, 2017 Utility $ 3,424 $ — $ — $ 3,424 Residential and Commercial 26,881 5,131 41 32,053 Total $ 30,305 $ 5,131 $ 41 $ 35,477
Schedule of finite-lived intangible assets, future amortization expense [Table Text Block]	Estimated future aggregate amortization expense of intangible assets -- The estimated aggregate amortization expense of intangible assets, as of December 31, 2017 , in each of the next five years follows: Estimated Future Amortization Expense Year ending December 31, 2018 $ 1,581 2019 1,451 2020 1,265 2021 826 2022 596

Short and Long-Term Debt and 38

Short and Long-Term Debt and Commitments Related to Letters of Credit (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of short-term debt [Table Text Block]	Short-term debt consisted of the following: December 31, 2017 2016 Notes payable $ 149 $ — Current portion of long-term debt 16,166 16,701 $ 16,315 $ 16,701
Schedule of long-term debt instruments [Table Text Block]	Long-term debt consisted of the following: December 31, 2017 2016 Revolving credit facility Swing-line borrowings $ — $ 10,000 LIBOR borrowings 100,000 57,000 100,000 67,000 Senior unsecured notes 18,000 24,000 Term loans 16,242 16,151 134,242 107,151 Less debt issuance costs 725 333 Less current portion 16,166 16,701 $ 117,351 $ 90,117

Self-Insurance Accruals (Tables

Self-Insurance Accruals (Tables)	12 Months Ended
	Dec. 31, 2017
Self-Insurance Accruals [Abstract]
Schedule of self-insurance accruals [Table Text Block]	Components of our self-insurance accruals for workers’ compensation, vehicle liability and general liability follow: December 31, 2017 2016 Workers' compensation $ 40,764 $ 38,811 Present value discount 2,346 2,236 38,418 36,575 Vehicle liability 5,536 4,763 General liability 23,740 21,500 Total 67,694 62,838 Less current portion 23,782 23,092 Noncurrent portion $ 43,912 $ 39,746
Schedule of changes in self-insurance accruals [Table Text Block]	The changes in our self-insurance accruals and the discount rate used for the workers’ compensation accrual are summarized in the table below. December 31, 2017 2016 Balance, beginning of year $ 62,838 $ 60,339 Provision for claims 34,884 33,404 Payment of claims 30,028 30,905 Balance, end of year $ 67,694 $ 62,838 Workers' compensation discount rate 2.00 % 2.20 %

Lease Obligations (Tables)

Lease Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Schedule of assets acquired under capital leases [Table Text Block]	Assets acquired under capital leases and included in property and equipment consisted of the following: December 31, 2017 2016 Equipment $ 3,481 $ 2,528 Less accumulated amortization 805 160 $ 2,676 $ 2,368
Schedule of future minimum lease payments for capital leases [Table Text Block]	Minimum rental commitments under all capital and noncancelable operating leases, as of December 31, 2017 , were as follows: Lease Obligations Minimum lease obligations Capital Operating Year ending December 31, 2018 $ 694 $ 7,243 2019 694 5,326 2020 682 3,945 2021 558 2,354 2022 — 1,794 2023 and after — 6,973 Total minimum lease payments 2,628 $ 27,635 Amounts representing interest 118 Present value of net minimum lease payments 2,510 Less current portion 651 Long-term capital lease obligations, December 31, 2017 $ 1,859
Schedule of future minimum rental payments for operating leases [Table Text Block]	Minimum rental commitments under all capital and noncancelable operating leases, as of December 31, 2017 , were as follows: Lease Obligations Minimum lease obligations Capital Operating Year ending December 31, 2018 $ 694 $ 7,243 2019 694 5,326 2020 682 3,945 2021 558 2,354 2022 — 1,794 2023 and after — 6,973 Total minimum lease payments 2,628 $ 27,635 Amounts representing interest 118 Present value of net minimum lease payments 2,510 Less current portion 651 Long-term capital lease obligations, December 31, 2017 $ 1,859

Common Shares, Redeemable Com41

Common Shares, Redeemable Common Shares and Preferred Shares (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of stock by class [Table Text Block]	Common and Redeemable Shares Outstanding -- The table below reconciles the activity of the common and redeemable shares outstanding: Common Shares Net of Treasury Shares Redeemable Shares Total Shares outstanding, December 31, 2015 17,713,576 7,773,052 25,486,628 Shares purchased (479,807 ) (1,012,275 ) (1,492,082 ) Shares sold 321,657 296,127 617,784 Stock subscription offering, employee cash purchases 48,730 — 48,730 Options exercised 262,080 — 262,080 Shares outstanding, December 31, 2016 17,866,236 7,056,904 24,923,140 Shares purchased (807,718 ) (890,009 ) (1,697,727 ) Shares sold 362,674 300,132 662,806 Stock subscription offering, employee cash purchases 90,645 — 90,645 Options exercised 241,995 — 241,995 Shares outstanding, December 31, 2017 17,753,832 6,467,027 24,220,859

Accumulated Other Comprehensi42

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of accumulated other comprehensive income (loss) [Table Text Block]	The following summarizes the components of other comprehensive income (loss) accumulated in shareholders’ equity: Foreign Currency Translation Adjustments Defined Benefit Pension Plans Accumulated Other Comprehensive Income (Loss) Balance at January 1, 2015 $ (1,151 ) $ (10,372 ) $ (11,523 ) Unrealized gains (losses) (5,093 ) — (5,093 ) Amounts reclassified from accumulated other comprehensive income (loss) — 4,774 4,774 Tax effect — (1,878 ) (1,878 ) Unrecognized amounts from defined benefit pension plans — 538 538 Tax effect — (212 ) (212 ) Net of tax amount (5,093 ) 3,222 (1,871 ) Balance at December 31, 2015 $ (6,244 ) $ (7,150 ) $ (13,394 ) Unrealized gains (losses) 744 — 744 Amounts reclassified from accumulated other comprehensive income (loss) — 2,844 2,844 Tax effect — (1,137 ) (1,137 ) Unrecognized amounts from defined benefit pension plans — (2,032 ) (2,032 ) Tax effect — 813 813 Net of tax amount 744 488 1,232 Balance at December 31, 2016 $ (5,500 ) $ (6,662 ) $ (12,162 ) Unrealized gains (losses) 2,195 — 2,195 Amounts reclassified from accumulated other comprehensive income (loss) — 4,822 4,822 Tax effect — (1,962 ) (1,962 ) Unrecognized amounts from defined benefit pension plans — (2,169 ) (2,169 ) Tax effect — 883 883 Net of tax amount 2,195 1,574 3,769 Balance at December 31, 2017 $ (3,305 ) $ (5,088 ) $ (8,393 )

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of share-based compensation arrangements by share-based payment award [Table Text Block]	Stock-based compensation expense under all share-based payment plans—our Employee Stock Purchase Plan, stock option plans, stock-settled stock appreciation rights, and performance-based restricted stock units—included in the results of operations follows: Year Ended December 31, 2017 2016 2015 Compensation expense, all share-based payment plans $ 4,049 $ 2,811 $ 2,327 Income tax benefit 1,315 823 694
Schedule of share-based compensation, employee stock purchase plan, activity [Table Text Block]	Purchases under the plan, at 85% of the fair market value of the common shares, have been as follows: Year Ended December 31, 2017 2016 2015 Number of employees participating 2,297 1,952 1,750 Shares purchased during the year 335,040 297,262 251,558 Weighted-average per share purchase price paid $ 15.27 $ 14.17 $ 13.11 Cumulative shares purchased since 1982 18,386,370 18,051,330 17,754,068
Schedule of share-based compensation, stock-settled stock appreciation rights award activity [Table Text Block]	The following table summarizes the SSARs as of December 31, 2017 : Stock-Settled Stock Appreciation Rights Number of Rights Weighted- Average Award Date Value Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Unvested, January 1, 2017 743,662 $ 2.75 Granted 152,000 3.57 Forfeited (8,060 ) 3.09 Vested (439,422 ) 2.67 Unvested, December 31, 2017 448,180 $ 3.10 2.5 years $ 998 $ 8,202
Schedule of share-based compensation, performance-based restricted stock units award activity [Table Text Block]	The following table summarizes restricted stock units as of December 31, 2017 : Restricted Stock Units Number of Stock Units Weighted- Average Grant Date Value Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Unvested, January 1, 2017 304,958 $ 13.22 Granted 80,350 17.01 Forfeited — — Vested (94,642 ) 12.76 Unvested, December 31, 2017 290,666 $ 14.41 2.2 years $ 2,063 $ 5,319 Employee PRSUs 253,242 $ 14.20 2.5 years $ 1,773 $ 4,634 Nonemployee Director RSUs 37,424 $ 15.85 1.4 years $ 290 $ 685
Schedule of share-based payment award, stock options, valuation assumptions [Table Text Block]	The fair values of stock-based awards granted were estimated at the dates of grant with the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Volatility rate 10.3 % 10.6 % 10.9 % Risk-free interest rate 2.2 % 1.8 % 2.1 % Expected dividend yield .7 % .7 % .7 % Expected life of awards (years) 8.9 9.5 9.3
Schedule of share-based compensation, stock options, activity [Table Text Block]	The following table summarizes activity under the stock option plans for the year ended December 31, 2017 : Stock Options Number of Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life Unrecognized Compensation Cost Aggregate Intrinsic Value Outstanding, January 1, 2017 1,599,296 $ 12.49 Granted 148,500 17.60 Exercised (138,107 ) 11.30 Forfeited (81,074 ) 13.34 Outstanding, December 31, 2017 1,528,615 $ 13.05 6.2 years $ 1,534 $ 8,025 Exercisable, December 31, 2017 800,615 $ 11.14 4.8 years $ 5,660
Schedule of share-based compensation, shares authorized under stock option plans, by exercise price range [Table Text Block]	Information regarding the stock options outstanding at December 31, 2017 is summarized below: Stock Options Exercise Price Number Outstanding Weighted-Average Remaining Contractual Life Weighted- Average Exercise Price Number Exercisable Weighted- Average Exercise Price Employee options: $ 8.00 144,948 1.8 years $ 8.00 144,948 $ 8.00 8.30 167,098 2.8 years 8.30 167,098 8.30 11.60 296,047 5.5 years 11.60 216,647 11.60 13.20 303,122 6.5 years 13.20 156,322 13.20 15.05 235,000 7.5 years 15.05 74,200 15.05 16.35 245,400 8.5 years 16.35 41,400 16.35 17.60 137,000 9.5 years 17.60 — 17.60 1,528,615 6.2 years $ 13.05 800,615 $ 11.14

Defined Benefit Pension Plans (

Defined Benefit Pension Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Schedule of changes in projected benefit obligations [Table Text Block]	The change in benefit obligations and the fair value of plans assets follows: December 31, 2017 2016 Change in benefit obligation Projected benefit obligation at beginning of year $ 24,833 $ 27,228 Service cost 530 370 Interest cost 1,002 1,243 Actuarial (gains)/losses 1,865 703 Amendments — 341 Settlements (8,400 ) (4,873 ) Benefits paid (427 ) (179 ) Projected benefit obligation at end of year $ 19,403 $ 24,833 Accumulated benefit obligation at end of year $ 19,403 $ 24,833
Schedule of changes in fair value of plan sssets [Table Text Block]	December 31, 2017 2016 Change in fair value of plan assets Fair value of plan assets at beginning of year $ 11,509 $ 15,216 Actual return on plan assets 845 400 Plan expenses, including PBGC premiums (513 ) (727 ) Employer contributions 4,091 1,672 Settlements (8,400 ) (4,873 ) Benefits paid (427 ) (179 ) Fair value of plan assets at end of year $ 7,105 $ 11,509
Schedule of net funded status [Table Text Block]	December 31, 2017 2016 Funded status of the plans Fair value of plan assets $ 7,105 $ 11,509 Projected benefit obligation 19,403 24,833 Funded status of the plans $ (12,298 ) $ (13,324 )
Schedule of amounts recognized in balance sheet [Table Text Block]	December 31, 2017 2016 Amounts reported in the consolidated balance sheets Current liability $ (175 ) $ (83 ) Noncurrent liability (12,123 ) (13,241 ) Funded status of the plans $ (12,298 ) $ (13,324 )
Schedule of amounts in accumulated other comprehensive income [Table Text Block]	Amounts included in accumulated other comprehensive income (loss), related to our defined benefit pension plans follow: At December 31, 2017 At December 31, 2016 Pretax Net of Tax Pretax Net of Tax Amounts reported in accumulated other comprehensive income Unrecognized net actuarial loss $ 8,086 $ 4,919 $ 10,675 $ 6,456 Unrecognized prior service cost 278 169 341 206 $ 8,364 $ 5,088 $ 11,016 $ 6,662
Schedule of amounts in accumulated other comprehensive income (loss) to be recognized over next fiscal year [Table Text Block]	The total amortization associated with these amounts that is expected to be recognized in net periodic benefit expense for 2018 follows: Year ending December 31, 2018 Pretax Net of Tax Amortization of Costs Expected to be Recognized Next Year Unrecognized net actuarial loss $ 727 $ 436 Unrecognized prior service cost 64 38 $ 791 $ 474
Schedule of accumulated benefit obligations in excess of fair value of plan assets [Table Text Block]	The aggregate projected benefit obligation, accumulated benefit obligation and fair value of plan assets for plans in which the fair value of plan assets is less than either the projected benefit obligation or accumulated benefit obligation follow: December 31, 2017 2016 For pension plans with accumulated benefit obligations in excess of plan assets Projected benefit obligation $ 19,403 $ 24,833 Accumulated benefit obligation 19,403 24,833 Fair value of plan assets 7,105 11,509
Schedule of assumptions used [Table Text Block]	The actuarial assumptions follow. The discount rates were used to measure the year-end benefit obligation and compute pension expense for the subsequent year. December 31, 2017 2016 2015 Actuarial assumptions Discount rate 3.70 % 4.20 % 4.70 % Expected long-term rate of return on plan assets 2.50 5.00 7.25
Components of pension expense (income) [Table Text Block]	Net periodic benefit expense (income) associated with the defined benefit pension plans included the following components: Year Ended December 31, 2017 2016 2015 Components of pension expense (income) Service costs--increase in benefit obligation earned $ 530 $ 370 $ 35 Interest cost on projected benefit obligation 1,002 1,243 1,486 Expected return on plan assets (638 ) (1,044 ) (1,576 ) Curtailment loss — — 49 Settlement loss 3,849 2,346 2,915 Amortization of net actuarial loss 909 951 1,400 Amortization of prior service cost 64 — 6 Net pension expense of defined benefit pension plans $ 5,716 $ 3,866 $ 4,315
Schedule of allocation of plan assets [Table Text Block]	The fair values of our pension plan assets at December 31, 2017 by asset category, using the three-level hierarchy of fair value inputs, were as follows: Fair Value Measurements at December 31, 2017 Using: Description Total Carrying Value at December 31, 2017 Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Asset Category Money market funds (a) $ 897 $ — $ 897 $ — U.S. large-cap equities Growth 576 576 — — Value 542 542 — — U.S. small/mid-cap equities Growth 246 246 — — Value 247 247 — — International equities Growth 376 376 — — Value 366 366 — — Fixed income 3,070 3,070 — — Multiclass world-allocation mutual funds 785 785 — — $ 7,105 $ 6,208 $ 897 $ — The fair values of our pension plan assets at December 31, 2016 by asset category, using the three-level hierarchy of fair value inputs, were as follows: Fair Value Measurements at December 31, 2016 Using: Description Total Carrying Value at December 31, 2016 Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Asset Category Money market funds (a) $ 2,882 $ — $ 2,882 $ — U.S. large-cap equities Growth 687 687 — — Value 729 729 — — U.S. small/mid-cap equities Growth 339 339 — — Value 339 339 — — International equities Growth 443 443 — — Value 514 514 — — Fixed income 4,669 4,669 — — Multiclass world-allocation mutual funds 907 907 — — $ 11,509 $ 8,627 $ 2,882 $ —
Schedule of expected benefit payments [Table Text Block]	The benefits, as of December 31, 2017 , expected to be paid to defined-benefit plan participants in each of the next five years, and in the aggregate for the five years thereafter, follow: Participants Benefits Estimated future payments Year ending December 31, 2018 $ 565 2019 675 2020 757 2021 809 2022 856 Years 2023 to 2027 4,835
Schedule of multiemployer plans [Table Text Block]	Our participation in the multiemployer defined benefit pension plans is summarized in the table below. The “EIN/Pension Plan Number” column provides the Employer Identification Number (“EIN”) and the three-digit plan number. The most recent Pension Protection Act of 2006 (the “PPA”) zone status is from the Form 5500, “Annual Return/Report of Employee Benefit Plan,” filed by the plan and certified by the plan's actuary. The PPA zone status describes plans that are underfunded. Among other factors, plans in the “critical” red zone are generally less than 65% funded; plans in the “endangered” yellow zone are less than 80% funded; and, plans in the “safe” green zone are at least 80% funded. P. Defined Benefit Pension Plans (continued) Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status FIP/RP Status Pending Implemented Davey Tree Contributions Surcharge Imposed Expiration Dates of Bargaining Agreement 2017 2016 2017 2016 2015 National Electric Benefit Fund 53-0181657/001 Green Green No $ 785 $ 712 $ 774 No Ranging from June 30, 2017 to December 31, 2018 Eighth District Electrical Pension Fund 84-6100393/001 Green Green No 102 90 119 No December 31, 2017 $ 887 $ 802 $ 893

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of income before income tax, domestic and foreign [Table Text Block]	Income before income taxes was attributable to the following sources: Year Ended December 31, 2017 2016 2015 United States $ 38,800 $ 35,867 $ 32,807 Canada (806 ) 1,377 2,451 Total $ 37,994 $ 37,244 $ 35,258
Schedule of components of income tax expense (benefit) [Table Text Block]	The provision for income taxes follows: Year Ended December 31, 2017 2016 2015 Currently payable: Federal $ 9,914 $ 12,216 $ 13,337 State 2,469 2,286 2,487 Canadian (262 ) 398 611 Total current 12,121 14,900 16,435 Deferred taxes 3,753 60 (2,975 ) Total taxes on income $ 15,874 $ 14,960 $ 13,460
Schedule of effective income tax rate reconciliation [Table Text Block]	A reconciliation of the expected statutory U.S. federal rate to our actual effective income tax rate follows: Year Ended December 31, 2017 2016 2015 Statutory U.S. federal tax rate 35.0 % 35.0 % 35.0 % State income taxes, net of federal benefit 4.9 4.0 3.7 Effect of Canadian income taxes .3 (.2 ) (.5 ) Nondeductible expenses 2.2 2.2 2.3 ESOP dividend deduction (.6 ) (.7 ) (.8 ) Uncertain tax adjustments and audit settlement (.2 ) .2 1.5 Valuation allowance — — (2.2 ) Income tax reform 2.5 — — All other, net (2.3 ) (.3 ) (.8 ) Effective income tax rate 41.8 % 40.2 % 38.2 %
Deferred tax assets and liabilities, noncurrent [Table Text Block]	Significant components of our noncurrent net deferred tax assets and liabilities at December 31, were as follows: December 31, 2017 2016 Deferred tax assets: Self-insurance accruals $ 14,186 $ 21,967 Accrued compensated absences 1,747 3,540 Accrued expenses and other liabilities 798 1,394 Accrued stock compensation 1,571 2,502 Defined benefit pension plans 2,289 4,019 Foreign tax credit carryforward 605 575 Other future deductible amounts, net 3,661 4,213 24,857 38,210 Deferred tax liabilities: Intangibles 969 297 Prepaid expenses 2,300 3,510 Property and equipment 16,773 23,274 20,042 27,081 Net deferred tax assets--noncurrent $ 4,815 $ 11,129
Summary of income tax contingencies [Table Text Block]	The balance of unrecognized benefits and the amount of related interest and penalties at December 31, were as follows: December 31, 2017 2016 Unrecognized tax benefits $ 2,581 $ 2,532 Portion, if recognized, would reduce tax expense and effective tax rate 1,948 2,053 Accrued interest on unrecognized tax benefits 128 107
Schedule of unrecognized tax benefits roll forward [Table Text Block]	The changes in our unrecognized tax benefits are summarized in the table below: Year Ended December 31, 2017 2016 2015 Balance, beginning of year $ 2,532 $ 2,557 $ 1,949 Additions based on tax positions related to the current year 650 402 642 Additions for tax positions of prior years (21 ) 51 52 Reductions for tax positions of prior years — (39 ) (63 ) Lapses in statutes of limitations (580 ) (439 ) (23 ) Balance, end of year $ 2,581 $ 2,532 $ 2,557

Earnings Per Share Information

Earnings Per Share Information (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of earnings per share calculation [Table Text Block]	Earnings per share is computed as follows (prior periods have been adjusted for the two-for-one stock split of our common shares effective June 1, 2017): Year Ended December 31, 2017 2016 2015 Income available to common shareholders: Net income $ 22,120 $ 22,284 $ 21,798 Weighted-average shares: Basic: Outstanding 24,793,086 25,378,600 26,058,736 Partially-paid share subscriptions 764,382 833,440 872,162 Basic weighted-average shares 25,557,468 26,212,040 26,930,898 Diluted: Basic from above 25,557,468 26,212,040 26,930,898 Incremental shares from assumed: Exercise of stock subscription purchase rights 146,453 142,746 135,428 Exercise of stock options and awards 993,141 892,568 888,254 Diluted weighted-average shares 26,697,062 27,247,354 27,954,580 Share data: Earnings per share--basic $ .87 $ .85 $ .81 Earnings per share--diluted $ .83 $ .82 $ .78

Operations by Business Segmen47

Operations by Business Segment and Geographic Information Operations by business segment (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment [Table Text Block]	Information on reportable segments and reconciliation to the consolidated financial statements follows: Utility Services Residential Commercial Services All Other Reconciling Adjustments Consolidated Fiscal Year 2017 Revenues $ 466,727 $ 446,028 $ 3,203 $ — $ 915,958 Income (loss) from operations 18,223 41,158 (2,634 ) (9,742 ) (a) 47,005 Interest expense (4,886 ) (4,886 ) Interest income 292 292 Other income (expense), net (4,417 ) (4,417 ) Income before income taxes $ 37,994 Depreciation $ 27,928 $ 19,384 $ — $ 3,390 (b) $ 50,702 Amortization 122 2,240 — 22 2,384 Capital expenditures 26,910 23,199 — 6,991 57,100 Segment assets, total 189,662 197,698 — 85,775 (c) 473,135 Fiscal Year 2016 Revenues $ 433,379 $ 410,878 $ 1,421 $ — $ 845,678 Income (loss) from operations 19,256 36,640 (4,318 ) (6,207 ) (a) 45,371 Interest expense (4,393 ) (4,393 ) Interest income 255 255 Other income (expense), net (3,989 ) (3,989 ) Income before income taxes $ 37,244 Depreciation $ 26,855 $ 17,198 $ — $ 3,231 (b) $ 47,284 Amortization 135 2,136 — 35 2,306 Capital expenditures 28,660 21,819 — 6,167 56,646 Segment assets, total 171,220 166,858 — 85,861 (c) 423,939 Fiscal Year 2015 Revenues $ 433,117 $ 386,327 $ 2,460 $ — $ 821,904 Income (loss) from operations 24,273 35,271 (5,368 ) (10,068 ) (a) 44,108 Interest expense (3,355 ) (3,355 ) Interest income 249 249 Other income (expense), net (5,744 ) (5,744 ) Income before income taxes $ 35,258 Depreciation $ 25,466 $ 15,592 $ — $ 3,619 (b) $ 44,677 Amortization 144 2,062 — 8 2,214 Capital expenditures 26,853 22,853 — 6,341 56,047 Segment assets, total 145,306 162,679 — 85,601 (c) 393,586
Schedule of revenue from external customers attributed to foreign countries by geographic area [Table Text Block]	Geographic Information -- The following presents revenues and long-lived assets by geographic territory: Year Ended December 31, 2017 2016 2015 Revenues United States $ 847,540 $ 775,870 $ 749,896 Canada 68,418 69,808 72,008 $ 915,958 $ 845,678 $ 821,904 December 31, 2017 2016 2015 Long-lived assets, net United States $ 242,118 $ 224,727 $ 213,323 Canada 21,893 20,439 19,329 $ 264,011 $ 245,166 $ 232,652

Fair Value Measurements and F48

Fair Value Measurements and Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value, assets measured on recurring basis [Table Text Block]	Our assets and liabilities measured at fair value on a recurring basis at December 31, 2017 and December 31, 2016 , were as follows: Fair Value Measurements at December 31, 2017 Using: Total Carrying Value at Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Description December 31, 2017 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 19,422 $ 19,422 $ — $ — Defined benefit pension plan assets 7,105 6,208 897 — Liabilities: Deferred compensation $ 2,146 $ — $ 2,146 $ — Fair Value Measurements at December 31, 2016 Using: Total Carrying Value at Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Description December 31, 2016 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 15,492 $ 15,492 $ — $ — Defined benefit pension plan assets 11,509 8,627 2.882 — Liabilities: Deferred compensation $ 1,837 $ — $ 1,837 $ —
Fair value, by balance sheet grouping [Table Text Block]	Financial instruments classified as noncurrent liabilities and their carrying values and fair values were as follows: December 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value Revolving credit facility, noncurrent $ 100,000 $ 100,000 $ 67,000 $ 67,000 Senior unsecured notes 12,000 12,389 18,000 18,509 Term loans, noncurrent 7,935 10,038 7,623 9,854 Total $ 119,935 $ 122,427 $ 92,623 $ 95,363

Quarterly Results of Operatio49

Quarterly Results of Operations Quarterly Results of Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information [Table Text Block]	The following is a summary of the results of operations for each quarter of 2017 and 2016 . We have given retroactive consideration to the two-for-one stock split of our common shares effective June 1, 2017. Fiscal 2017, Three Months Ended Apr 1 Jul 1 Sep 30 Dec 31 Revenues $ 192,813 $ 245,037 $ 249,588 $ 228,520 Gross profit (revenues less costs and expenses, operating) 59,154 93,512 91,973 83,986 Income (loss) from operations (4,342 ) 25,312 18,701 7,334 Net income (loss) (3,887 ) 14,223 10,237 1,547 Net income (loss) per share -- Basic $ (.15 ) $ .57 $ .41 $ .04 Net income (loss) per share -- Diluted $ (.15 ) $ .55 $ .39 $ .04 ESOT valuation per share $ 17.60 $ 17.60 $ 18.30 $ 19.10 Fiscal 2016, Three Months Ended Apr 2 Jul 2 Oct 1 Dec 31 Revenues $ 180,833 $ 224,763 $ 223,719 $ 216,363 Gross profit (revenues less costs and expenses, operating) 57,660 87,631 81,386 77,515 Income (loss) from operations (5,120 ) 24,286 15,042 11,163 Net income (loss) (4,188 ) 13,309 8,141 5,022 Net income (loss) per share -- Basic $ (.16 ) $ .52 $ .32 $ .17 Net income (loss) per share -- Diluted $ (.16 ) $ .50 $ .31 $ .17 ESOT valuation per share $ 16.35 $ 16.35 $ 16.95 $ 17.60 Fourth quarters 2017 and 2016 include a decrease in casualty insurance expense that had the effect of increasing the fourth quarter gross profit for 2017 and 2016 by approximately $2,735 and $2,810, respectively.

Our Business Reportable segment

Our Business Reportable segments (Details)	12 Months Ended
	Dec. 31, 2017
Number of reportable segments	2

Summary of Significant Accoun51

Summary of Significant Accounting Policies (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jul. 04, 2015	Dec. 31, 2017	Dec. 31, 2016
Property, plant and equipment [Line Items]
Goodwill, impairment loss	$ 0	$ 0	$ 0
Minimum [Member]
Property, plant and equipment [Line Items]
Intangible assets, estimated useful life (in years)		1 year
Maximum [Member]
Property, plant and equipment [Line Items]
Intangible assets, estimated useful life (in years)		10 years
Land improvements [Member] | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		5 years
Land improvements [Member] | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		20 years
Buildings [Member] | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		5 years
Buildings [Member] | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		30 years
Equipment [Member] | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		3 years
Equipment [Member] | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		10 years
Leasehold improvements [Member] | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		5 years
Leasehold improvements [Member] | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)		20 years

Summary of Significant Accoun52

Summary of Significant Accounting Policies Concentration of Risk (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Risks and uncertainties [Abstract]
Concentration risk, percentage	11.00%	12.00%	11.00%

Summary of Significant Accoun53

Summary of Significant Accounting Policies Stock split adjustment (Details)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stock split, conversion ratio	2

Summary of Significant Accoun54

Summary of Significant Accounting Policies Goodwill impairment (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jul. 04, 2015	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, impairment loss	$ 0	$ 0	$ 0

Recent Accounting Guidance Rece

Recent Accounting Guidance Recent accounting guidance (Details)	Dec. 31, 2016USD ($)
Accounting Standards Update 2017 04 [Member]
New accounting pronouncement or change in accounting principle, cumulative effect of change on equity or net assets	$ 0
Accounting Standards Update 2017 09 [Member]
New accounting pronouncement or change in accounting principle, cumulative effect of change on equity or net assets	0
Additional paid-in capital | Accounting Standards Update 2016 09 [Member]
New accounting pronouncement or change in accounting principle, cumulative effect of change on equity or net assets	$ 162

Business Combinations (Details)

Business Combinations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business acquisition [Line Items]
Investments in businesses	$ 13,264	$ 4,888	$ 4,149
Liabilities assumed	2,713	216	0
Debt issued	3,099	875	1,500
Goodwill	5,131	817	1,410
Goodwill acquired during period, tax deductible amount	$ 5,131	$ 1,410	$ 1,410

Accounts Receivable, Net and 57

Accounts Receivable, Net and Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts receivable, net
Accounts receivable	$ 143,244	$ 128,202
Receivables under contractual arrangements	29,895	21,541
Accounts receivable, gross, current	173,139	149,743
Less allowances for doubtful accounts	4,468	3,609
Accounts receivable, net	168,671	146,134
Other current assets
Refundable income taxes	587	548
Other	784	1,315
Other current assets, total	1,371	1,863
Other assets, noncurrent
Assets invested for self-insurance	19,422	15,492
Investment--cost-method affiliate	1,218	1,168
Deferred income taxes	4,815	11,129
Other	3,701	3,565
Other assets, noncurrent, total	29,156	31,354
Accrued expenses
Employee compensation	20,794	18,438
Accrued compensated absences	9,267	9,215
Self-insured medical claims	3,193	2,961
Customer advances, deposits	1,672	2,997
Income taxes payable	3,443	953
Taxes, other than income	2,279	2,166
Other	2,168	929
Accrued expenses, total	42,816	37,659
Other liabilities, noncurrent
Pension and retirement plans	14,759	15,982
Other	5,207	4,837
Other liabilities, noncurrent, total	$ 19,966	$ 20,819

Supplemental Operating Inform58

Supplemental Operating Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Nonoperating Income (Expense) [Abstract]
Other nonoperating expense, net	$ (4,417)	$ (3,989)	$ (5,744)
Foreign currency gains (losses)	$ 55	$ 113	$ (854)

Supplemental Cash Flow Inform59

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental cash flow information
Interest paid	$ 5,096	$ 4,329	$ 3,386
Income taxes paid, net	10,005	10,578	16,679
Noncash transactions
Debt issued for purchases of businesses	(3,099)	(875)	(1,500)
Detail of acquisitions:
Receivables	1,753	0	0
Operating supplies	0	157	0
Prepaid expense	128	55	0
Equipment	1,904	2,485	1,264
Deposits and other	52	0	11
Intangibles	4,296	1,374	1,464
Goodwill	5,131	817	1,410
Liabilities assumed	2,713	216	0
Cash paid	$ 7,452	$ 3,797	$ 2,649

Identified Intangible Assets 60

Identified Intangible Assets and Goodwill, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, gross	$ 34,798	$ 30,488
Accumulated amortization	28,604	26,417
Identified intangibles, net	6,194	4,071
Goodwill	35,477	30,305
Identified intangible assets and goodwill, net	$ 41,671	34,376
Customer lists/relationships
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, remaining amortization period	2 years 9 months 18 days
Finite-lived intangible assets, gross	$ 21,487	17,822
Accumulated amortization	$ 16,846	15,171
Employment-related
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, remaining amortization period	2 years 2 months 12 days
Finite-lived intangible assets, gross	$ 7,333	7,032
Accumulated amortization	$ 6,624	6,386
Tradenames
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, remaining amortization period	2 years 10 months 24 days
Finite-lived intangible assets, gross	$ 5,978	5,634
Accumulated amortization	$ 5,134	$ 4,860

Identified Intangible Assets 61

Identified Intangible Assets and Goodwill, Net Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, balance at January 1, 2017	$ 30,305
Goodwill, acquisitions	5,131	$ 817	$ 1,410
Goodwill, translation and other adjustments	41
Goodwill, balance at December 31, 2017	35,477	30,305
Utility
Goodwill [Roll Forward]
Goodwill, balance at January 1, 2017	3,424
Goodwill, acquisitions	0
Goodwill, translation and other adjustments	0
Goodwill, balance at December 31, 2017	3,424	3,424
Residential and Commercial
Goodwill [Roll Forward]
Goodwill, balance at January 1, 2017	26,881
Goodwill, acquisitions	5,131
Goodwill, translation and other adjustments	41
Goodwill, balance at December 31, 2017	$ 32,053	$ 26,881

Identified Intangible Assets 62

Identified Intangible Assets and Goodwill, Net (Future Amortization of Intangibles) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Finite-lived intangible assets, net, amortization expense, fiscal year maturity [Abstract]
Year ending December 31, 2018	$ 1,581
2,019	1,451
2,020	1,265
2,021	826
2,022	$ 596

Short and Long-Term Debt and 63

Short and Long-Term Debt and Commitments Related to Letters of Credit Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Jul. 22, 2010
Debt instrument [Line Items]
Notes payable	$ 149	$ 0
Revolving credit facility, noncurrent	100,000	67,000
Senior unsecured notes	18,000	24,000	$ 30,000
Term loans	16,242	16,151
Long-term debt	134,242	107,151
Less debt issuance costs	725	333
Less current portion	16,166	16,701
Long-term debt, excluding current maturities	117,351	90,117
Short-term debt	16,315	16,701
Swing-line borrowings [Member]
Debt instrument [Line Items]
Revolving credit facility, noncurrent	0	10,000
LIBOR borrowings [Member]
Debt instrument [Line Items]
Revolving credit facility, noncurrent	$ 100,000	$ 57,000

Short and Long-Term Debt and 64

Short and Long-Term Debt and Commitments Related to Letters of Credit Narrative (Details)	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jul. 22, 2010USD ($)
Debt instrument [Line Items]
Committed under credit facility	$ 7,042,000
Senior unsecured notes, interest rate	5.09%
Revolving credit facility, current borrowing capacity	$ 250,000,000
Revolving credit facility, maximum borrowing capacity	325,000,000
Swing line commitment	25,000,000
Senior unsecured notes	$ 18,000,000	$ 24,000,000	$ 30,000,000
Number of principal payments	5
Anniversary when principal payments begin	6
Unused commitments under credit facility	$ 146,912,000
Revolving credit facility, noncurrent	100,000,000	67,000,000
Revolving credit facility borrowings	$ 100,000,000	$ 67,000,000
Long-term debt, weighted average interest rate	3.75%	3.56%
Long-term debt, fiscal year maturity [Abstract]
2,018	$ 16,166,000
2,019	6,890,000
2,020	6,894,000
2,021	4,292,000
2,022	$ 100,000,000
Minimum [Member]
Debt instrument [Line Items]
Line of credit facility, commitment fee percentage	0.10%
Maximum [Member]
Debt instrument [Line Items]
Line of credit facility, commitment fee percentage	0.225%
Line of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, noncurrent	$ 103,088,000
Revolving credit facility borrowings	103,088,000
Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	$ 63,242,000	$ 64,225,000
Base rate [Member] | Line of credit [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	0.50%
London Interbank Offered Rate (LIBOR) [Member] | Line of credit [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	1.50%
London Interbank Offered Rate (LIBOR) [Member] | Line of credit [Member] | Minimum [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	0.875%
London Interbank Offered Rate (LIBOR) [Member] | Line of credit [Member] | Maximum [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	1.50%
Revolving credit facility [Member] | Minimum [Member]
Debt instrument [Line Items]
Interest coverage ratio	3
Revolving credit facility [Member] | Maximum [Member]
Debt instrument [Line Items]
Ratio of Indebtedness to Net Capital	3
Revolving credit facility [Member] | Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	$ 3,088,000	4,071,000
Accounts receivable securitization [Member]
Debt instrument [Line Items]
Senior unsecured notes, interest rate	0.90%
Long-term debt, fiscal year maturity [Abstract]
Unused commitment fee threshold percent	0.50
Debt instrument variable rate base rate calculation, default rate	2.00%
Accounts receivable securitization [Member] | Letter of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 100,000,000
Letters of credit outstanding	$ 58,150,000
Long-term debt, fiscal year maturity [Abstract]
Debt instrument, term (in years)	1 year
Accounts receivable securitization [Member] | Letter of credit [Member] | Minimum [Member]
Long-term debt, fiscal year maturity [Abstract]
Letter of credit, unused capacity, commitment fee percentage	0.0035
Accounts receivable securitization [Member] | Letter of credit [Member] | Maximum [Member]
Long-term debt, fiscal year maturity [Abstract]
Letter of credit, unused capacity, commitment fee percentage	0.0045
Accounts receivable securitization [Member] | Base rate, federal funds [Member]
Long-term debt, fiscal year maturity [Abstract]
Debt instrument, variable rate, base rate calculation	0.50%
Line of credit [Member] | Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	$ 2,004,000	$ 2,004,000
Line of credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	0.75%
Line of credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	1.50%
Letter of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 100,000,000
Previous agreement [Member] | Accounts receivable securitization [Member] | Letter of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 60,000,000

Self-Insurance Accruals (Detail

Self-Insurance Accruals (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Self-Insurance Accruals [Abstract]
Workers' compensation			$ 40,764	$ 38,811
Present value discount			2,346	2,236
Workers' compensation, net of discount			38,418	36,575
Vehicle liability			5,536	4,763
General liability			23,740	21,500
Total	$ 62,838	$ 60,339	67,694	62,838
Less current portion			23,782	23,092
Noncurrent portion			$ 43,912	$ 39,746
Loss contingency accrual [Roll Forward]
Balance, beginning of year	62,838	60,339
Provision for claims	34,884	33,404
Payment of claims	30,028	30,905
Balance, end of year	$ 67,694	$ 62,838
Workers' compensation discount rate	2.00%	2.20%

Lease Obligations (Details)

Lease Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital leased assets [Line Items]
Assets acquired under captial lease, net	$ 2,676	$ 2,368
Operating leases, maximum lease terms	5 years
Capital leases, future minimum payments due, fiscal year maturity [Abstract]
Year ending December 31, 2018	$ 694
2,019	694
2,020	682
2,021	558
2,022	0
2023 and after	0
Total minimum lease payments	2,628
Amounts representing interest	118
Present value of net minimum lease payments	2,510
Less current portion	651	170
Long-term capital lease obligations, December 31, 2017	1,859	2,173
Operating leases, future minimum payments due, fiscal year maturity [Abstract]
Year ending December 31, 2018	7,243
2,019	5,326
2,020	3,945
2,021	2,354
2,022	1,794
2023 and after	6,973
Total minimum lease payments	27,635
Operating leases, rent expense	7,998	7,536	$ 7,398
Equipment [Member]
Capital leased assets [Line Items]
Equipment	3,481	2,528
Less accumulated amortization	$ 805	$ 160

Common Shares, Redeemable Com67

Common Shares, Redeemable Common Shares and Preferred Shares Common shares outstanding (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares
Stock split, conversion ratio	2
Preferred shares
Preferred stock, shares authorized	4,000,000
Preferred stock, par value | $ / shares	$ 0
Preferred stock, shares issued	0
Redeemable stock, outstanding	6,467,027	7,056,904	7,773,052
Common stock, number of shares, par value and other disclosures [Abstract]
Common stock, shares authorized	48,000,000	48,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1
Common stock, shares issued	36,446,890	35,856,856	35,140,708
Treasury stock, shares	18,692,901	17,990,620	17,427,132
Common shares, direct sales	39,564
Common shares, value, direct sales | $	$ 700
Stock issued during period, shares, employee benefit plan	80,178
Stock issued during period, value, employee retirement plan | $	$ 1,420
Common shares, employer matching contribution, shares	208,024
Employee retirement plan, employer match | $	$ 3,661
Stock issued during period, shares, employee stock purchase plan	335,040
Increase (decrease) in stockholders' equity [Roll Forward]
Shares outstanding, beginning of year	24,923,140	25,486,628
Shares purchased	(1,697,727)	(1,492,082)
Shares sold	662,806	617,784
Stock subscription offering, employee cash purchases	90,645	48,730
Options exercised	241,995	262,080
Shares outstanding, end of year	24,220,859	24,923,140	25,486,628
Per share amounts and common shares outstanding [Abstract]
Share-based compensation arrangement by share-based payment award, options, exercisable, number	800,615
Stock subscription offering, number of partially-paid subscriptions	764,382
Stock subscription offering, number of rights outstanding	309,389
Treasury stock [Member]
Common stock, number of shares, par value and other disclosures [Abstract]
Shares purchased, value | $	$ 30,566	$ 25,290	$ 25,395
Increase (decrease) in stockholders' equity [Roll Forward]
Shares purchased	(1,698,000)	(1,492,000)	(1,648,000)
Shares sold	663,000	617,000	576,000
401KSOP [Member]
Common stock, number of shares, par value and other disclosures [Abstract]
Accrued 401K match | $	$ 3,991

Common Shares, Redeemable Com68

Common Shares, Redeemable Common Shares and Preferred Shares Stock subscription (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Stock subscription offering [Abstract]
Stock subscription offering, number of rights outstanding	309,389
Stock subscription offering, subscription price | $ / shares	$ 9.85
Stock subscription offering, number of shares subscribed	1,275,428
stock subscription offering, value of shares subscribed | $	$ 12,563,000
Stock subscription offering, minimum financed amount | $	$ 5,000
Stock subscription offering, down payment	10.00%
Stock subscription offering, term	7 years
Stock subscription offering interest rate	2.00%
Stock subscription offering, minimum amount to receive right | $	$ 5,000
stock subscription offering, number of shares purchased to receive one right	3
Stock subscription offering, number of rights issued	423,600
Stock subscription offering, portion exercisable per year	14.29%
Stock subscription offering, right expiration term	7 years

Common Shares, Redeemable Com69

Common Shares, Redeemable Common Shares and Preferred Shares Common shares by class (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Shares, Outstanding	24,220,859	24,923,140	25,486,628
Treasury Stock, Shares, Acquired	(1,697,727)	(1,492,082)
Shares sold	662,806	617,784
Stock subscription offering, employee cash purchases	90,645	48,730
Options exercised	241,995	262,080
Permanent equity [Member]
Class of Stock [Line Items]
Shares, Outstanding	17,753,832	17,866,236	17,713,576
Treasury Stock, Shares, Acquired	(807,718)	(479,807)
Shares sold	362,674	321,657
Stock subscription offering, employee cash purchases	90,645	48,730
Options exercised	241,995	262,080
Temporary equity [Member]
Class of Stock [Line Items]
Shares, Outstanding	6,467,027	7,056,904	7,773,052
Treasury Stock, Shares, Acquired	(890,009)	(1,012,275)
Shares sold	300,132	296,127
Stock subscription offering, employee cash purchases	0	0
Options exercised	0	0

Accumulated Other Comprehensi70

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	$ (12,162)	$ (13,394)	$ (11,523)
Unrealized gains (losses)	2,195	744	(5,093)
Amounts reclassified from accumulated other comprehensive income (loss)	4,822	2,844	4,774
Tax effect	(1,962)	(1,137)	(1,878)
Unrecognized amounts from defined benefit pension plans	(2,169)	(2,032)	538
Tax effect	883	813	(212)
Net of tax amount	3,769	1,232	(1,871)
Balance at the end of the year	(8,393)	(12,162)	(13,394)
Foreign Currency Translation Adjustments
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	(5,500)	(6,244)	(1,151)
Unrealized gains (losses)	2,195	744	(5,093)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Tax effect	0	0	0
Unrecognized amounts from defined benefit pension plans	0	0	0
Tax effect	0	0	0
Net of tax amount	2,195	744	(5,093)
Balance at the end of the year	(3,305)	(5,500)	(6,244)
Defined Benefit Pension Plans
Increase (decrease) in accumulated other comprehensive income (loss) [Roll Forward]
Balance at the beginning of the year	(6,662)	(7,150)	(10,372)
Unrealized gains (losses)	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	4,822	2,844	4,774
Tax effect	(1,962)	(1,137)	(1,878)
Unrecognized amounts from defined benefit pension plans	2,169	2,032	538
Tax effect	(883)	(813)	(212)
Net of tax amount	1,574	488	3,222
Balance at the end of the year	$ (5,088)	$ (6,662)	$ (7,150)

The Davey 401KSOP and Employe71

The Davey 401KSOP and Employee Stock Ownership Plan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Employee stock ownership plan (ESOP), initial shares in ESOP | shares	120,000
Employee stock ownership plan (ESOP), shares adjusted for stock splits | shares	11,520,000
Employee stock ownership plan (ESOP), initial value in ESOP	$ 2,700
Defined contribution plan, eligible age	21
Defined contribution plan, service requirement for eligibility (in years)	1 year
Number of put option periods	2
Duration of put option periods (in days)	60 days
Employee Stock Ownership Plan (ESOP), Fair Value of Shares Subject to Repurchase Obligation	$ 3,843	$ 1,148
Company shares held in 401KSOP and ESOP, fair value	119,677	123,053
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP):	123,520	124,201
Employee retirement plan, employer match	$ 3,794	$ 3,661	$ 3,373
First 1% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	100.00%
1% to 4% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	50.00%
Minimum [Member] | 1% to 4% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	1.00%
Maximum [Member] | First 1% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	1.00%
Maximum [Member] | 1% to 4% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	4.00%

Stock-Based Compensation Employ

Stock-Based Compensation Employee stock purchase plan (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016$ / sharesshares	Dec. 31, 2015$ / sharesshares
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Shares purchased during the year	335,040
The Davey Employee Stock Purchase Plan [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Number of employees participating	2,297	1,952	1,750
Shares purchased during the year	335,040	297,262	251,558
Weighted-average per share purchase price paid | $ / shares	$ 15.27	$ 14.17	$ 13.11
Cumulative shares purchased since 1982	18,386,370	18,051,330	17,754,068

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of outstanding shares available for grant, maximum	5.00%
Cumulative percentage of outstanding shares available for grant in a year, maximum	10.00%
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $	$ 4,049	$ 2,811	$ 2,327
Income tax benefit | $	$ 1,315	$ 823	$ 694
Employee Stock Purchase Plan [Abstract]
Shares purchased during the year | shares	335,040
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Volatility rate	10.30%	10.60%	10.90%
Risk-free interest rate	2.20%	1.80%	2.10%
Expected dividend yield	0.70%	0.70%	0.70%
Expected life of awards (years)	8 years 10 months 24 days	9 years 6 months	9 years 3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance | shares	1,599,296
Granted | shares	148,500
Exercised | shares	(138,107)
Forfeited | shares	81,074
Outstanding, ending balance | shares	1,528,615	1,599,296
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercisable, ending balance | shares	800,615
Outstanding, weighted average exercise price, ending balance	$ 13.05	$ 12.49
Granted, weighted average exercise price	17.60
Exercised, weighted average exercise price	11.30
Forfeited, weighted average exercise price	13.34
Exercisable, weighted average exercise price	$ 11.14
Unrecognized compensation cost | $	$ 1,534
Exercisable, weighted average remaining contractual life (years)	4 years 9 months 18 days
Outstanding, aggregate intrinsic value | $	$ 8,025
Exercisable, aggregate intrinisic value | $	5,660
Excess tax benefits | $	691	$ 1,113	$ 352
Employee stock option [Member]
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $	$ 705	596
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted average remaining contractual life (years)	6 years 2 months 12 days
Number outstanding | shares	1,528,615
Outstanding options, weighted average exercise price	$ 13.05
Number exercisable | shares	800,615
Exercisable options, weighted average exercise price	$ 11.14
Employee stock option [Member] | $8.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	8
Upper range limit	$ 8
Number outstanding | shares	144,948
Weighted average remaining contractual life (years)	1 year 9 months 18 days
Outstanding options, weighted average exercise price	$ 8
Number exercisable | shares	144,948
Exercisable options, weighted average exercise price	$ 8
Employee stock option [Member] | $8.30 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	8.3
Upper range limit	$ 8.3
Number outstanding | shares	167,098
Weighted average remaining contractual life (years)	2 years 9 months 18 days
Outstanding options, weighted average exercise price	$ 8.30
Number exercisable | shares	167,098
Exercisable options, weighted average exercise price	$ 8.30
Employee stock option [Member] | $11.60 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	11.6
Upper range limit	$ 11.6
Number outstanding | shares	296,047
Weighted average remaining contractual life (years)	5 years 6 months
Outstanding options, weighted average exercise price	$ 11.60
Number exercisable | shares	216,647
Exercisable options, weighted average exercise price	$ 11.60
Employee stock option [Member] | $13.20 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	13.2
Upper range limit	$ 13.2
Number outstanding | shares	303,122
Weighted average remaining contractual life (years)	6 years 6 months
Outstanding options, weighted average exercise price	$ 13.20
Number exercisable | shares	156,322
Exercisable options, weighted average exercise price	$ 13.20
Employee stock option [Member] | $15.05 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	15.05
Upper range limit	$ 15.05
Number outstanding | shares	235,000
Weighted average remaining contractual life (years)	7 years 6 months
Outstanding options, weighted average exercise price	$ 15.05
Number exercisable | shares	74,200
Exercisable options, weighted average exercise price	$ 15.05
Employee stock option [Member] | $16.35 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	16.35
Upper range limit	$ 16.35
Number outstanding | shares	245,400
Weighted average remaining contractual life (years)	8 years 6 months
Outstanding options, weighted average exercise price	$ 16.35
Number exercisable | shares	41,400
Exercisable options, weighted average exercise price	$ 16.35
Employee stock option [Member] | $17.60 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Lower range limit	17.60
Upper range limit	$ 17.60
Number outstanding | shares	137,000
Weighted average remaining contractual life (years)	9 years 6 months
Outstanding options, weighted average exercise price	$ 17.60
Number exercisable | shares	0
Exercisable options, weighted average exercise price	$ 17.60
Stock Appreciation Rights (SARs) [Member]
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $	$ 1,035	$ 591	489
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Vesting period	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning balance | shares	743,662
Granted | shares	152,000
Forfeited | shares	8,060
Vested | shares	(439,422)
Unvested, ending balance | shares	448,180	743,662
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Unvested, weighted average award date value, beginning balance	$ 2.75
Granted, weighted average award date value	3.57
Forfeited, weighted average award date value	3.09
Vested, weighted average award date value	2.67
Unvested, weighted average award date value, ending balance	$ 3.10	$ 2.75
Weighted average remaining contractual life (years)	2 years 6 months 15 days
Unrecognized compensation cost | $	$ 998
Aggregate intrinsic value, unvested | $	$ 8,202
Equity Option [Member]
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $			494
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Vesting period	10 years
Restricted Stock Units (RSUs) [Member]
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $	$ 1,421	$ 897	775
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning balance | shares	304,958
Granted | shares	80,350
Forfeited | shares	0
Vested | shares	(94,642)
Unvested, ending balance | shares	290,666	304,958
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Unvested, weighted average award date value, beginning balance	$ 13.22
Granted, weighted average award date value	17.01
Forfeited, weighted average award date value	0
Vested, weighted average award date value	12.76
Unvested, weighted average award date value, ending balance	$ 14.41	$ 13.22
Weighted average remaining contractual life (years)	2 years 2 months 12 days
Unrecognized compensation cost | $	$ 2,063
Aggregate intrinsic value, unvested | $	$ 5,319
Employee PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted | shares	68,086
Unvested, ending balance | shares	253,242
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Unvested, weighted average award date value, ending balance	$ 14.20
Weighted average remaining contractual life (years)	2 years 6 months
Unrecognized compensation cost | $	$ 1,773
Aggregate intrinsic value, unvested | $	$ 4,634
Nonemployee Director PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted | shares	12,264
Unvested, ending balance | shares	37,424
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Unvested, weighted average award date value, ending balance	$ 15.85
Weighted average remaining contractual life (years)	1 year 4 months 24 days
Unrecognized compensation cost | $	$ 290
Aggregate intrinsic value, unvested | $	685
The Davey Employee Stock Purchase Plan [Member]
Salaries, Wages and Officers' Compensation [Abstract]
Compensation expense, stock-based compensation | $	$ 888	$ 727	$ 569
Employee Stock Purchase Plan [Abstract]
Employee stock purchase plan, service period (in years)	1 year
Employee stock purchase plan, percentage of market price, purchase date	85.00%
Employee stock purchase, discount from market price, purchase date	15.00%
Number of employees participating	2,297	1,952	1,750
Shares purchased during the year | shares	335,040	297,262	251,558
Cumulative shares purchased since 1982 | shares	18,386,370	18,051,330	17,754,068

Defined Benefit Pension Plans C

Defined Benefit Pension Plans Change in benefit obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined benefit plan, change in benefit obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 24,833	$ 27,228
Service cost	530	370	$ 35
Interest cost	1,002	1,243	1,486
Actuarial (gains)/losses	1,865	703
Amendments	0	341
Settlements	(8,400)	(4,873)
Benefits paid	(427)	(179)
Projected benefit obligation at end of year	19,403	24,833	$ 27,228
Accumulated benefit obligation at end of year	$ 19,403	$ 24,833

Defined Benefit Pension Plans75

Defined Benefit Pension Plans Change in fair value of plan assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Defined benefit plan, change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 11,509	$ 15,216
Actual return on plan assets	845	400
Plan expenses, including PBGC premiums	(513)	(727)
Employer contributions	4,091	1,672
Settlements	8,400	4,873
Benefits paid	(427)	(179)
Fair value of plan assets at end of year	$ 7,105	$ 11,509
Plan for bargaining employees not covered by union pension plans [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, number of employees settled	94
Defined benefit plan, change in fair value of plan assets [Roll Forward]
Employer contributions	$ 522
Settlements	$ 453
Employee retirement plan [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, number of employees settled		224

Defined Benefit Pension Plans F

Defined Benefit Pension Plans Funded status of the plans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	$ 7,105	$ 11,509	$ 15,216
Projected benefit obligation	19,403	24,833	$ 27,228
Funded status of the plans	$ (12,298)	$ (13,324)

Defined Benefit Pension Plans A

Defined Benefit Pension Plans Amounts reported in the consolidated balance sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined benefit plan disclosure [Line Items]
Current liability	$ (175)	$ (83)
Noncurrent liability	(12,123)	(13,241)
Funded status of the plans	$ (12,298)	$ (13,324)

Defined Benefit Pension Plans78

Defined Benefit Pension Plans Amounts reported in accumulated other comprehensive income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts reported in accumulated other comprehensive income
Unrecognized net actuarial loss, pretax	$ 8,086	$ 10,675
Unrecognized net actuarial loss, net of tax	4,919	6,456
Unrecognized prior service cost, pretax	278	341
Unrecognized prior service cost, net of tax	169	206
Amounts reported in accumulated other comprehensive income, pretax	8,364	11,016
Amounts reported in accumulated other comprehensive income, net of tax	5,088	6,662
Amortization of Costs Expected to be Recognized Next Year
Unrecognized net actuarial loss, pretax	727
Unrecognized net actuarial loss, net of tax	436
Unrecognized prior service cost, pretax	64
Unrecognized prior service cost, net of tax	38
Amortization of costs expected to be recognized next year, pretax	791
Amortization of costs expected to be recognized next year, net of tax	474
For pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	19,403	24,833	$ 27,228
Accumulated benefit obligation	19,403	24,833
Fair value of plan assets	$ 7,105	$ 11,509	$ 15,216

Defined Benefit Pension Plans79

Defined Benefit Pension Plans Actuarial Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined benefit plan disclosure [Line Items]
Discount rate	3.70%	4.20%	4.70%
Expected long-term rate of return on plan assets	2.50%	5.00%	7.25%
Equity securities [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, target plan asset allocations range minimum	20.00%
Defined benefit plan, target plan asset allocations range maximum	40.00%
Fixed income and cash [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, target plan asset allocations	100.00%
Defined benefit plan, target plan asset allocations range minimum	50.00%
Defined benefit plan, target plan asset allocations range maximum	70.00%
Alternative investments [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, target plan asset allocations range minimum	0.00%
Defined benefit plan, target plan asset allocations range maximum	15.00%
Fixed Income Investments [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, target plan asset allocations range maximum	5.00%
Minimum [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, risk management practices, investment evaluation period	3 years
Maximum [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, risk management practices, investment evaluation period	5 years

Defined Benefit Pension Plans80

Defined Benefit Pension Plans Components of Pension Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs--increase in benefit obligation earned	$ 530	$ 370	$ 35
Interest cost on projected benefit obligation	1,002	1,243	1,486
Expected return on plan assets	(638)	(1,044)	(1,576)
Curtailment loss	0	0	49
Settlement loss	3,849	2,346	2,915
Amortization of net actuarial loss	909	951	1,400
Amortization of prior service cost	64	0	6
Net pension expense of defined benefit pension plans	$ 5,716	$ 3,866	$ 4,315

Defined Benefit Pension Plans81

Defined Benefit Pension Plans Fair Value of Plan Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)
Defined benefit plan disclosure [Line Items]
Total carrying value	$ 11,509	$ 7,105
Fair value of plan assets	11,509	7,105	$ 15,216
Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	8,627	6,208
Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	2,882	897
Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Money market funds (a)
Defined benefit plan disclosure [Line Items]
Total carrying value	2,882	897
Money market funds (a) | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Money market funds (a) | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	2,882	897
Money market funds (a) | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large-cap equities, growth [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	687	576
U.S. large-cap equities, growth [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	687	576
U.S. large-cap equities, growth [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large-cap equities, growth [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large-cap equities, value [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	729	542
U.S. large-cap equities, value [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	729	542
U.S. large-cap equities, value [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large-cap equities, value [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small/mid-cap equities, growth [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	339	246
U.S. small/mid-cap equities, growth [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	339	246
U.S. small/mid-cap equities, growth [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small/mid-cap equities, growth [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small/mid-cap equities, value [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	339	247
U.S. small/mid-cap equities, value [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	339	247
U.S. small/mid-cap equities, value [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small/mid-cap equities, value [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
International equities, growth [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	443	376
International equities, growth [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	443	376
International equities, growth [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
International equities, growth [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
International equities, value [Member]
Defined benefit plan disclosure [Line Items]
Total carrying value	514	366
International equities, value [Member] | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	514	366
International equities, value [Member] | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
International equities, value [Member] | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income
Defined benefit plan disclosure [Line Items]
Total carrying value	4,669	3,070
Fixed income | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	4,669	3,070
Fixed income | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Multiclass world-allocation mutual funds
Defined benefit plan disclosure [Line Items]
Total carrying value	907	785
Multiclass world-allocation mutual funds | Quoted prices in active markets, (level 1) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	907	785
Multiclass world-allocation mutual funds | Significant other observable inputs, (level 2) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	0	0
Multiclass world-allocation mutual funds | Significant unobservable inputs, (level 3) [Member]
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0
Employee retirement plan [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, number of employees settled	224

Defined Benefit Pension Plans E

Defined Benefit Pension Plans Expected Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Defined benefit plan disclosure [Line Items]
Year ending December 31, 2018	$ 565
2,019	675
2,020	757
2,021	809
2,022	856
Years 2023 to 2027	4,835
Pension plans, defined benefit [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plans, estimated future employer contributions in next fiscal year	$ 638

Defined Benefit Pension Plans M

Defined Benefit Pension Plans Multiemployer Pension Plans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	$ 887	$ 802	$ 893
National Electric Benefit Fund [Member]
Multiemployer Plans [Line Items]
Number of collective-bargaining agreements	9
Multiemployer plan, period contributions	$ 785	712	774
Eighth District Electrical Pension Fund [Member]
Multiemployer Plans [Line Items]
Number of collective-bargaining agreements	1
Multiemployer plan, period contributions	$ 102	$ 90	$ 119

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Tax charge due to remeasurement of deferred tax assets and liabilities	$ 1,000
Estimated tax liability due to transition toll tax					$ 6,100
Income before income taxes
Income before income taxes		$ 37,994	$ 37,244	$ 35,258
Provision for income taxes
Federal		9,914	12,216	13,337
State		2,469	2,286	2,487
Canadian		(262)	398	611
Total current		12,121	14,900	16,435
Deferred taxes		3,753	60	(2,975)
Total taxes on income		$ 15,874	$ 14,960	$ 13,460
Tax rate reconciliation
Statutory U.S. federal tax rate		35.00%	35.00%	35.00%
State income taxes, net of federal benefit		4.90%	4.00%	3.70%
Effect of Canadian income taxes		0.30%	(0.20%)	(0.50%)
Nondeductible expenses		2.20%	2.20%	2.30%
ESOP dividend deduction		(0.60%)	(0.70%)	(0.80%)
Uncertain tax adjustments and audit settlement		(0.20%)	0.20%	1.50%
Valuation allowance		(0.00%)	(0.00%)	(2.20%)
Income tax reform		2.50%	0.00%	0.00%
All other, net		(2.30%)	(0.30%)	(0.80%)
Effective income tax rate		41.80%	40.20%	38.20%
Current deferred tax assets and liabilities, net
Deferred income tax assets--noncurrent					24,857	$ 38,210
Net deferred tax assets--noncurrent					4,815	11,129
Noncurrent deferred tax assets and liabilities, net
Self-insurance accruals					14,186	21,967
Accrued compensated absences					1,747	3,540
Accrued expenses and other liabilities					798	1,394
Accrued stock compensation					1,571	2,502
Defined benefit pension plans					2,289	4,019
Foreign tax credit carryforward					605	575
Other future deductible amounts, net					3,661	4,213
Deferred tax assets, net--noncurrent					24,857	38,210
Intangibles					969	297
Prepaid expenses					2,300	3,510
Property and equipment					16,773	23,274
Deferred tax liability, noncurrent					20,042	27,081
Net deferred tax assets--noncurrent					4,815	11,129
Undistributed earnings of foreign subsidiaries					30,329
Unrecognized benefits and related interest and penalties
Unrecognized tax benefits	2,581	$ 2,532	$ 2,557	$ 1,949	2,581	2,532
Portion, if recognized, would reduce tax expense and effective tax rate					1,948	2,053
Accrued interest on unrecognized tax benefits					$ 128	$ 107
Reconciliation of unrecognized tax benefits
Balance, beginning of year		2,532	2,557	1,949
Additions based on tax positions related to the current year		650	402	642
Additions for tax positions of prior years		21	51	52
Reductions for tax positions of prior years		0	(39)	(63)
Lapses in statutes of limitations		(580)	(439)	(23)
Balance, end of year	$ 2,581	2,581	2,532	2,557
United States [Member]
Income before income taxes
Income before income taxes		38,800	35,867	32,807
Canada [Member]
Income before income taxes
Income before income taxes		$ (806)	$ 1,377	$ 2,451

Earnings Per Share Informatio85

Earnings Per Share Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 1,547	$ 10,237	$ 14,223	$ (3,887)	$ 5,022	$ 8,141	$ 13,309	$ (4,188)	$ 22,120	$ 22,284	$ 21,798
Weighted-average shares, basic
Outstanding									24,793,086	25,378,600	26,058,736
Partially-paid share subscriptions									764,382	833,440	872,162
Basic weighted-average shares									25,557,468	26,212,040	26,930,898
Weighted-average shares, diluted
Exercise of stock subscription purchase rights									146,453	142,746	135,428
Exercise of stock options and awards									993,141	892,568	888,254
Diluted weighted-average shares									26,697,062	27,247,354	27,954,580
Earnings per share--basic	$ 0.04	$ 0.41	$ 0.57	$ (0.15)	$ 0.17	$ 0.32	$ 0.52	$ (0.16)	$ 0.87	$ 0.85	$ 0.81
Earnings per share--diluted	$ 0.04	$ 0.39	$ 0.55	$ (0.15)	$ 0.17	$ 0.31	$ 0.50	$ (0.16)	$ 0.83	$ 0.82	$ 0.78

Operations by Business Segmen86

Operations by Business Segment and Geographic Information Operations by Busines Segment (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jul. 01, 2017USD ($)	Apr. 01, 2017USD ($)	Dec. 31, 2016USD ($)	Oct. 01, 2016USD ($)	Jul. 02, 2016USD ($)	Apr. 02, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments										2
Revenues										$ 915,958	$ 845,678	$ 821,904
Income (loss) from operations		$ 7,334	$ 18,701	$ 25,312	$ (4,342)	$ 11,163	$ 15,042	$ 24,286	$ (5,120)	47,005	45,371	44,108
Interest expense										4,886	4,393	3,355
Interest income										292	255	249
Other										(4,417)	(3,989)	(5,744)
Income before income taxes										37,994	37,244	35,258
Depreciation										50,702	47,284	44,677
Amortization										2,384	2,306	2,214
Capital expenditures										57,100	56,646	56,047
Segment assets, total		473,135				423,939				473,135	423,939	393,586
Utility Services
Segment Reporting Information [Line Items]
Revenues										466,727	433,379	433,117
Income (loss) from operations										18,223	19,256	24,273
Depreciation										27,928	26,855	25,466
Amortization										122	135	144
Capital expenditures										26,910	28,660	26,853
Segment assets, total		189,662				171,220				189,662	171,220	145,306
Residential Commercial Services
Segment Reporting Information [Line Items]
Revenues										446,028	410,878	386,327
Income (loss) from operations										41,158	36,640	35,271
Depreciation										19,384	17,198	15,592
Amortization										2,240	2,136	2,062
Capital expenditures										23,199	21,819	22,853
Segment assets, total		197,698				166,858				197,698	166,858	162,679
All Other
Segment Reporting Information [Line Items]
Revenues										3,203	1,421	2,460
Income (loss) from operations										(2,634)	(4,318)	(5,368)
Depreciation										0	0	0
Amortization										0	0	0
Capital expenditures										0	0	0
Segment assets, total		0				0				0	0	0
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues										0	0	0
Income (loss) from operations	[1]									(9,742)	(6,207)	(10,068)
Interest expense										4,886	4,393	3,355
Interest income										292	255	249
Other										(4,417)	(3,989)	(5,744)
Depreciation	[2]									3,390	3,231	3,619
Amortization										22	35	8
Capital expenditures										6,991	6,167	6,341
Segment assets, total	[3]	$ 85,775				$ 85,861				$ 85,775	$ 85,861	$ 85,601
[1]	Reconciling adjustments from segment reporting to consolidated external financial reporting include reclassification of depreciation expense and allocation of corporate expenses.
[2]	Adjustments to declining-balance method depreciation expense from straight-line method and depreciation and amortization of corporate assets.
[3]	Corporate assets include cash, prepaid expenses, corporate facilities, enterprise-wide information systems and other nonoperating assets.

Operations by Business Segmen87

Operations by Business Segment and Geographic Information Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 915,958	$ 845,678	$ 821,904
Long-lived assets, net	264,011	245,166	232,652
United States [Member]
Segment Reporting Information [Line Items]
Revenues	847,540	775,870	749,896
Long-lived assets, net	242,118	224,727	213,323
Canada [Member]
Segment Reporting Information [Line Items]
Revenues	68,418	69,808	72,008
Long-lived assets, net	$ 21,893	$ 20,439	$ 19,329

Fair Value Measurements and F88

Fair Value Measurements and Financial Instruments Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 22, 2010
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	$ 7,105	$ 11,509	$ 15,216
Revolving credit facility, noncurrent	100,000	67,000
Senior unsecured notes	18,000	24,000		$ 30,000
Total	117,351	90,117
Quoted prices in active markets, (level 1) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	6,208	8,627
Significant other observable inputs, (level 2) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	897	2,882
Significant unobservable inputs (level 3) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	0	0
Fair value measurements, recurring [Member] | Quoted prices in active markets, (level 1) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	19,422	15,492
Defined benefit pension plan assets	6,208	8,627
Deferred compensation	0	0
Fair value measurements, recurring [Member] | Significant other observable inputs, (level 2) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	0	0
Defined benefit pension plan assets	897	3
Deferred compensation	2,146	1,837
Fair value measurements, recurring [Member] | Significant unobservable inputs (level 3) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	0	0
Defined benefit pension plan assets	0	0
Deferred compensation	0	0
Fair value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	100,000	67,000
Senior unsecured notes	12,389	18,509
Term loans, noncurrent	10,038	9,854
Total	122,427	95,363
Total carrying value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	100,000	67,000
Senior unsecured notes	12,000	18,000
Term loans, noncurrent	7,935	7,623
Total	119,935	92,623
Total carrying value [Member] | Fair value measurements, recurring [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	19,422	15,492
Defined benefit pension plan assets	7,105	11,509
Deferred compensation	$ 2,146	$ 1,837

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Letter of credit [Member]
Letters of credit outstanding	$ 63,242	$ 64,225
Former Davey employee defendants [Member]
Loss contingency, number of defendants	1
Wolf employee defendants [Member]
Loss contingency, number of defendants	2
Defendants for which Davey has retained separate counsel [Member]
Loss contingency, number of defendants	3
Former Wolf employee defendants [Member]
Loss contingency, number of defendants	1

Quarterly Results of Operatio90

Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 228,520	$ 249,588	$ 245,037	$ 192,813	$ 216,363	$ 223,719	$ 224,763	$ 180,833	$ 915,958	$ 845,678	$ 821,904
Gross profit (revenues less costs and expenses, operating)	83,986	91,973	93,512	59,154	77,515	81,386	87,631	57,660
Income (loss) from operations	7,334	18,701	25,312	(4,342)	11,163	15,042	24,286	(5,120)	47,005	45,371	44,108
Net income (loss)	$ 1,547	$ 10,237	$ 14,223	$ (3,887)	$ 5,022	$ 8,141	$ 13,309	$ (4,188)	$ 22,120	$ 22,284	$ 21,798
Net income (loss) per share -- Basic	$ 0.04	$ 0.41	$ 0.57	$ (0.15)	$ 0.17	$ 0.32	$ 0.52	$ (0.16)	$ 0.87	$ 0.85	$ 0.81
Net income (loss) per share -- Diluted	0.04	0.39	0.55	(0.15)	0.17	0.31	0.50	(0.16)	$ 0.83	$ 0.82	$ 0.78
ESOT valuation per share	$ 19.10	$ 18.30	$ 17.60	$ 17.60	$ 17.60	$ 16.95	$ 16.35	$ 16.35
Decrease in casualty insurance expense	$ 2,735				$ 2,810