Davey Tree Expert 10-K 8 Mar 21 2020 FY Annual report Financial data

Cover Page Document

Cover Page Document - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 05, 2021
Cover [Abstract]
Document type	10-K
Document annual report	true
Document period end date	Dec. 31, 2020
Document transition report	false
Entity file number	000-11917
Entity registrant name	THE DAVEY TREE EXPERT COMPANY
Entity well-known seasoned issuer	No
Entity voluntary filers	No
Entity current reporting status	Yes
Entity interactive data current	Yes
Entity filer category	Accelerated Filer
Entity emerging growth company	false
Entity small business	false
ICFR Auditor Attestation Flag	true
Entity shell company	false
Entity common stock, shares outstanding		22,824,170
Entity public float	$ 514,173,814
Entity central index key	0000277638
Current fiscal year end date	--12-31
Document fiscal year focus	2020
Document fiscal period focus	FY
Amendment flag	false
Entity incorporation, state or country code	OH
Entity tax identification number	34-0176110
Entity address, address description	1500 North Mantua Street
Entity address, address line one	P.O. Box 5193
Entity address, city or town	Kent
Entity address, state or province	OH
Entity address, postal zip code	44240
City area code	330
Local phone number	673-9511

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash	$ 16,201	$ 11,000
Accounts receivable, net	252,921	231,311
Operating supplies	10,206	12,127
Prepaid expenses	24,956	25,664
Other current assets	778	1,323
Total current assets	305,062	281,425
Property and equipment:
Land and land improvements	19,731	19,270
Buildings and leasehold improvements	49,460	44,414
Equipment	623,847	604,211
Property and equipment	693,038	667,895
Less accumulated depreciation	488,321	468,045
Property and equipment, net	204,717	199,850
Right-of-use assets - operating leases	55,893	40,033
Other assets	29,756	22,397
Intangible assets, net	11,670	10,934
Goodwill	48,256	42,285
Total assets	655,354	596,924
Current liabilities:
Current portion of long-term debt, finance lease liabilities and short-term debt	21,813	26,503
Current portion of operating lease liabilities	19,124	14,665
Accounts payable	42,787	41,191
Accrued expenses	98,441	52,431
Self-insurance accruals	37,707	30,882
Total current liabilities	219,872	165,672
Long-term debt	2,101	68,423
Senior unsecured notes	74,967	74,931
Lease liabilities - finance leases	6,479	1,795
Lease liabilities - operating leases	36,612	25,200
Self-insurance accruals	71,573	64,801
Other liabilities	10,689	11,701
Total liabilities	422,293	412,523
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP): 5,113 and 5,147 shares at redemption value as of December 31, 2020 and 2019	153,387	124,555
Common shareholders' equity:
Common shares, $1.00 par value, per share; 48,000 shares authorized; 37,801 and 37,767 shares issued and outstanding before deducting treasury shares and which excludes 5,113 and 5,147 shares subject to redemption as of December 31, 2020 and 2019	37,801	37,767
Additional paid-in capital	110,069	96,366
Retained earnings	206,711	177,711
Accumulated other comprehensive loss	(4,547)	(5,403)
Stockholders' equity before treasury stock	350,034	306,441
Less: Cost of Common shares held in treasury; 20,094 shares in 2020 and 19,737 in 2019	270,360	246,595
Total common shareholders' equity	79,674	59,846
Total liabilities and shareholders' equity	$ 655,354	$ 596,924
Redeemable stock, outstanding	5,112,884	5,146,882
Common stock, par value (in dollars per share)	$ 1
Common stock, shares authorized	48,000,000
Common stock, shares outstanding	37,801,000	37,767,000
Treasury stock, shares	20,093,608	19,736,957
Common stock, shares issued	37,800,876	37,766,878

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 1,287,552	$ 1,143,720	$ 1,024,791
Costs and expenses:
Operating	823,297	730,096	666,141
Selling	227,392	209,148	184,388
General and administrative	89,528	76,738	67,462
Depreciation	53,888	57,292	54,914
Amortization of intangible assets	2,827	2,545	2,055
Gain on sale of assets, net	(3,581)	(2,055)	(5,106)
Costs and expenses	1,193,351	1,073,764	969,854
Income from operations	94,201	69,956	54,937
Other income (expense):
Interest expense	(6,899)	(8,514)	(7,039)
Interest income	2,135	348	350
Other	(5,555)	(8,112)	(11,505)
Income before income taxes	83,882	53,678	36,743
Income taxes	22,945	12,628	9,385
Net income	$ 60,937	$ 41,050	$ 27,358
Share data:
Earnings per share--basic	$ 2.77	$ 1.79	$ 1.12
Earnings per share--diluted	$ 2.65	$ 1.71	$ 1.07
Weighted-average shares outstanding:
Basic	21,981,950	22,906,264	24,388,738
Diluted	23,033,086	23,978,089	25,480,618

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income	$ 60,937	$ 41,050	$ 27,358
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments gains/(losses)	895	1,186	(2,514)
Defined benefit pension plans:
Net loss arising during the year	(152)	(147)	(273)
Amortization of defined benefit pension items:
Net actuarial (gain) loss	66	(1,456)	6,084
Prior service cost	47	48	62
Amortization of defined benefit pension items:	113	(1,408)	6,146
Defined benefit pension plan adjustments	(39)	(1,555)	5,873
Total other comprehensive income (loss), net of tax	856	(369)	3,359
Comprehensive income	$ 61,793	$ 40,681	$ 30,717

Statements of Consolidated Shar

Statements of Consolidated Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common shares	Additional paid-in capital	Common shares subscribed, unissued	Retained earnings	Retained earningsCumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss), net of tax	Common shares held in treasury	Common shares subscription receivable
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2017	$ 36,177		$ 36,447	$ 58,554	$ 7,529	$ 142,142		$ (8,393)	$ (198,327)	$ (1,775)
Increase (decrease) in stockholders' equity [Roll Forward]
Net income	27,358					27,358
Change in 401KSOP and ESOP related shares	4,472		825	15,245		(11,598)
Shares sold to employees	17,437			6,820					10,617
Stock Issued During Period, Value, Stock Options Exercised	2,471			145					2,326
Stock Issued During Period, Value, Other	1,675			(99)	(730)				1,458	1,046
Stock-based compensation	$ 1,958			1,958
Dividends declared per share	$ 0.10
Dividends	$ (2,387)					(2,387)
Adoption of ASU 2014-09		$ (355)					$ (355)
Currency translation adjustments	(2,514)							(2,514)
Defined benefit pension plans	5,873							5,873
Shares purchased	(51,116)								(51,116)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2018	41,049		37,272	82,623	6,799	155,160		(5,034)	(235,042)	(729)
Balance at the end of the year at Dec. 31, 2018	$ (5,034)
Common shares, at end of year at Dec. 31, 2018	37,271,606
Balance at the beginning of the year at Dec. 31, 2017	$ (8,393)
Increase (decrease) in stockholders' equity [Roll Forward]
Net income	41,050					41,050
Change in 401KSOP and ESOP related shares	(5,507)		495	10,180		(16,182)
Shares sold to employees	14,552			5,604					8,948
Stock Issued During Period, Value, Stock Options Exercised	1,788			(1,850)					3,638
Stock Issued During Period, Value, Other	2,450			(1,988)	(6,799)				10,508	729
Stock-based compensation	$ 1,797			1,797
Dividends declared per share	$ 0.10
Dividends	$ (2,317)					(2,317)
Currency translation adjustments	1,186							1,186
Defined benefit pension plans	(1,555)							(1,555)
Shares purchased	(34,647)								(34,647)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2019	59,846		37,767	96,366	0	177,711		(5,403)	246,595	0
Balance at the end of the year at Dec. 31, 2019	$ (5,403)
Common shares, at end of year at Dec. 31, 2019	37,766,878
Common shares, at beginning of year at Dec. 31, 2018	37,271,606
Balance at the beginning of the year at Dec. 31, 2018	$ (5,034)
Increase (decrease) in stockholders' equity [Roll Forward]
Shares purchased, shares	1,600,595
Shares sold	(723,482)
Net income	$ 60,937					60,937
Change in 401KSOP and ESOP related shares	(28,831)		34	801		(29,666)
Shares sold to employees	23,307			10,973					12,334
Stock Issued During Period, Value, Stock Options Exercised	2,519			(461)					2,980
Stock-based compensation	$ 2,390			2,390
Dividends declared per share	$ 0.10
Dividends	$ (2,271)					(2,271)
Currency translation adjustments	895							895
Defined benefit pension plans	(39)							(39)
Shares purchased	(39,079)								(39,079)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2020	79,674		$ 37,801	$ 110,069	$ 0	$ 206,711		$ (4,547)	$ (270,360)	$ 0
Balance at the end of the year at Dec. 31, 2020	$ (4,547)
Common shares, at end of year at Dec. 31, 2020	37,800,876
Common shares, at beginning of year at Dec. 31, 2019	37,766,878
Balance at the beginning of the year at Dec. 31, 2019	$ (5,403)
Increase (decrease) in stockholders' equity [Roll Forward]
Common shares, subscribed, value	$ (12,563)
Common shares, subscribed, shares	(1,275,428)
Shares purchased, shares	1,597,929
Shares sold	(1,011,047)

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 60,937	$ 41,050	$ 27,358
Adjustments to reconcile net income to net cash provided by operating activities net of assets/liabilities acquired:
Depreciation	53,888	57,292	54,914
Amortization	2,827	2,545	2,055
Gain on sale of assets	(3,581)	(2,055)	(5,106)
Deferred income taxes	(5,358)	1,398	3,880
Other	(29)	2,860	134
Changes in operating assets and liabilities, net of assets acquired:
Accounts receivable	(21,366)	(32,573)	(26,829)
Accounts payable and accrued expenses	52,577	7,188	(1,970)
Self-insurance accruals	13,597	8,791	16,844
Other assets, net	(1,411)	(3,143)	(9,176)
Adjustments to reconcile net income to net cash provided by operating activities	91,144	42,303	34,746
Net cash provided by operating activities	152,081	83,353	62,104
Capital expenditures:
Equipment	(46,407)	(52,841)	(58,620)
Land and buildings	(5,243)	(5,514)	(1,790)
Proceeds from sales of property and equipment	4,787	3,562	7,494
Purchases of businesses, net of cash acquired	(8,065)	(8,529)	(8,461)
Net cash used in investing activities	(54,928)	(63,322)	(61,377)
Financing activities
Revolving credit facility borrowings	596,500	469,500	507,500
Revolving credit facility payments	658,500	501,000	514,000
Proceeds from notes payable	269,445	114,140	74,716
Payments of notes payable	(281,985)	(95,007)	(26,339)
Payments of financing leases	(1,996)	(1,282)	(891)
Purchase of common shares for treasury	(39,079)	(34,647)	(51,116)
Sale of common shares from treasury	25,827	18,060	20,536
Cash received on common-share subscriptions	0	729	1,046
Dividends	(2,271)	(2,317)	(2,387)
Net cash (used in) provided by financing activities	(92,059)	(31,824)	9,065
Effect of exchange rate changes on cash	107	132	(252)
Increase (Decrease) in cash	5,201	(11,661)	9,540
Cash, beginning of year	11,000	22,661	13,121
Cash, end of year	$ 16,201	$ 11,000	$ 22,661

Our Business

Our Business	12 Months Ended
	Dec. 31, 2020
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 and rights-of-way and chemical brush control, 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, 2020
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 and certain prior-year amounts have been reclassified to conform to the current year presentation. In addition, our financial statements and corresponding footnotes for prior periods have been recast to reflect the retrospective application of the change in accounting principle discussed in the Self-Insurance Accruals section of this note. 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, stock valuation and revenue recognition. Actual results could differ from those estimates. While the coronavirus ("COVID-19") pandemic did not have a material adverse effect on our reported results for our fiscal year, the overall extent and duration of the impact of COVID-19 on businesses and economic activity generally remains unclear. The extent to which our operations may be impacted by COVID-19 will depend largely on future developments, which are highly uncertain due to its continual evolution, such as the previous resurgences in cases and the emergence of new strains of COVID-19, and cannot be accurately predicted, including new information which may emerge concerning the severity of the outbreak and actions by government authorities to contain the pandemic or treat its impact, including reimposing previously-lifted measures and the possibility additional measures will be put in place, among other things. The Company’s fiscal quarters each contain thirteen operating weeks, with the exception of the fourth quarter of a 53-week fiscal year, which contains fourteen operating weeks. 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 20 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 year to seven 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 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. Our annual impairment assessment date has been designated as the first day of our fourth fiscal 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, not to exceed the carrying value of the goodwill allocated to that reporting unit. We conducted our annual impairment tests and determined that no impairment loss was required to be recognized in 2020 or for any prior periods. There were no events or circumstances from the date of our assessment through December 31, 2020 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. Self-insurance accruals consist of the projected settlement value of reported and unreported claims. 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. Estimating ultimate losses of reported and unreported claims is subject to a high degree of variability as it involves complex estimates that are generally derived using a variety of actuarial estimation techniques and numerous assumptions and expectations about future events, many of which are highly uncertain. 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. 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. Changes in claims incurred, claim severity, or other estimates and judgments used by management could have a material impact on the amount and timing of expense for any period. During the year ended December 31, 2020, we changed our method of accounting for our workers' compensation accruals from measuring the liabilities on a discounted basis to an undiscounted basis. We believe that measuring the workers' compensation accruals on an undiscounted basis is preferable because it simplifies the accounting for the liabilities, provides consistency with our other lines of coverage (vehicle liability and general liability) and results in financial statement presentation consistent with our industry peers. As a result of this change in method of accounting, our financial statements and corresponding footnotes for all prior periods have been recast to reflect the retrospective application of the change in accounting principle. We recorded the cumulative effect for the change in accounting principle as a decrease of $1,693 to retained earnings as of January 1, 2018. This change decreased our retained earnings by $2,059 and $2,312 at December 31, 2019 and 2018, respectively. The following tables present the effects of the change in accounting principle to our financial statements: December 31, 2019 Balance Sheets Prior to Change in Accounting Principle Effect of Change Recast Self-insurance accruals (long term) $ 62,113 $ 2,688 $ 64,801 Other assets (noncurrent) 22,335 62 22,397 Other liabilities (long term) 12,268 (567) 11,701 Retained earnings 179,770 (2,059) 177,711 December 31, 2019 December 31, 2018 Statement of Operations Prior to Change in Accounting Principle Effect of Change Recast Prior to Change in Accounting Principle Effect of Change Recast Operating expense $ 730,507 $ (411) $ 730,096 $ 665,388 $ 753 $ 666,141 Income from operations 69,545 411 69,956 55,690 (753) 54,937 Income before income taxes 53,267 411 53,678 37,496 (753) 36,743 Income tax expense 12,470 158 12,628 9,519 (134) 9,385 Net income (loss) 40,797 253 41,050 27,977 (619) 27,358 Net income per share: Basic 1.78 0.01 1.79 1.15 (0.03) 1.12 Diluted 1.70 0.01 1.71 1.10 (0.03) 1.07 December 31, 2019 December 31, 2018 Cash Flow Prior to Change in Accounting Principle Effect of Change Recast Prior to Change in Accounting Principle Effect of Change Recast Net income $ 40,797 $ 253 $ 41,050 $ 27,977 $ (619) $ 27,358 Deferred income taxes 1,240 158 1,398 4,014 (134) 3,880 Self-insurance accruals 9,202 (411) 8,791 16,091 753 16,844 Net cash provided by operating activities 83,353 — 83,353 62,104 — 62,104 Quarterly Results of Operations (Unaudited) Prior to Change in Accounting Principle Effect of Change Recast Fiscal 2020, Three Months Ended Mar 28 Gross profit (revenues less costs and expenses, operating) $ 89,887 $ (212) $ 89,675 Income from operations 3,934 (212) 3,722 Net income (loss) 173 (194) (21) Net income (loss) per share -- Basic 0.01 (0.01) — Net income (loss) per share -- Diluted 0.01 (0.01) — Fiscal 2020, Three Months Ended June 27 Gross profit (revenues less costs and expenses, operating) $ 128,187 $ 78 $ 128,265 Income from operations 44,311 78 44,389 Net income (loss) 29,785 96 29,881 Net income (loss) per share -- Basic 1.31 — 1.31 Net income (loss) per share -- Diluted 1.24 0.01 1.25 Quarterly Results of Operations (Unaudited) Prior to Change in Accounting Principle Effect of Change Recast Fiscal 2020, Three Months Ended Sept 26 Gross profit (revenues less costs and expenses, operating) $ 128,943 $ (128) $ 128,815 Income from operations 35,500 (128) 35,372 Net income (loss) 24,627 (92) 24,535 Net income (loss) per share -- Basic 1.08 (0.01) 1.07 Net income (loss) per share -- Diluted 1.03 — 1.03 Fiscal 2019, Three Months Ended Mar 30 Gross profit (revenues less costs and expenses, operating) $ 81,873 $ (153) $ 81,720 Income from operations 2,966 (153) 2,813 Net income (loss) (493) (100) (593) Net income (loss) per share -- Basic (0.02) (0.01) (0.03) Net income (loss) per share -- Diluted (0.02) (0.01) (0.03) Fiscal 2019, Three Months Ended June 29 Gross profit (revenues less costs and expenses, operating) $ 113,656 $ 6 $ 113,662 Income from operations 30,282 6 30,288 Net income (loss) 19,747 (18) 19,729 Net income (loss) per share -- Basic 0.86 — 0.86 Net income (loss) per share -- Diluted 0.82 — 0.82 Fiscal 2019, Three Months Ended Sept 28 Gross profit (revenues less costs and expenses, operating) $ 114,336 $ (56) $ 114,280 Income from operations 22,783 (56) 22,727 Net income (loss) 13,434 (37) 13,397 Net income (loss) per share -- Basic 0.59 — 0.59 Net income (loss) per share -- Diluted 0.56 — 0.56 Fiscal 2019, Three Months Ended Dec 31 Gross profit (revenues less costs and expenses, operating) $ 103,348 $ 614 $ 103,962 Income from operations 13,514 614 14,128 Net income (loss) 8,109 407 8,516 Net income (loss) per share -- Basic 0.35 0.02 0.37 Net income (loss) per share -- Diluted 0.34 0.01 0.35 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 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 --We recognize revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers. See Note S for a detailed description of our revenue recognition policy. 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 are as 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 17% of revenues during 2020, 12% in 2019 and 12% in 2018. 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 converted 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. 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, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recent Accounting Guidance	Recent Accounting Guidance Accounting Standards Adopted in 2019 Accounting Standards Update 2016-02, Leases (Topic 842) --In February 2016, the FASB issued Accounting Standards Update ("ASU") 2016-02, “Leases (Topic 842).” ASU 2016-02, along with several subsequent updates, requires lessees to recognize assets and liabilities created by leases on their balance sheet along with additional disclosure information. The Company adopted the standard on January 1, 2019 using the Comparative Under ASC 840 approach, which permitted the Company to not recast historical periods for the adoption, and utilized practical expedients as available. The adoption of the new standard resulted in the recording, as of January 1, 2019, of operating right-of-use assets and lease liabilities of $37,429. The adoption of the new standard did not impact our consolidated results of operations and had no impact on our cash flows. Accounting Standards Update 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) --In February 2018, the FASB issued ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220)." ASU 2018-02 provides an option to reclassify the stranded tax effects within accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act of 2017. The Company adopted ASU 2018-02 effective January 1, 2019 and did not elect to reclassify the income tax effects of the Tax Cuts and Jobs Act from accumulated other comprehensive income to retained earnings. SEC Release No. 33-10532, Disclosure Update and Simplification --In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of shareholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of shareholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. We have incorporated the changes required by SEC Release No. 33-10532 in this report. Accounting Standard Adopted in 2020 Accounting Standards Update 2016-13, Financial Instruments - Credit Losses (Topic 326) --In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses (Topic 326)." ASU 2016-13 replaced the incurred loss impairment methodology in U.S. GAAP for most financial instruments, including trade receivables, with an impairment model, known as the current expected credit loss model, that is based on expected losses rather than incurred losses. The Company adopted the new standard effective January 1, 2020, and it did not have a material effect on the Company's results of operations. Accounting Standard Not Yet Adopted Accounting Standards Update 2019-12, Income Taxes (Topic 740)– Simplifying the Accounting for Income Taxes --In December 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12)", which simplifies the accounting for income taxes by removing certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, including applicable interim periods. The Company will adopt ASU 2019-12 beginning January 1, 2021. The adoption of ASU 2019-12 is not anticipated to have a material effect on the Company's financial statements.

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Business Combinations [Text Block]	Business Combinations Our investments in businesses were: (a) $11,150 in 2020, including liabilities assumed of $613 and debt issued of $2,472; (b) $12,620 in 2019, including liabilities assumed of $1,479 and debt issued of $2,612; and (c) $13,244 in 2018, including $2,381 of liabilities assumed and debt issued of $2,402. 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 measurement period for purchase price allocations ends as soon as information of the facts and circumstances becomes available, but does not exceed one year from the acquisition date. The Company’s intangible assets consist of tradenames, non-competition agreements and customer relationships. The tradenames and customer relationships intangible assets were assigned an average six-year useful life, and the non-competition agreements were assigned an average five-year useful life. 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 $5,635 in 2020 (all of which is deductible for tax purposes), $4,174 in 2019 ($1,610 of which is deductible for tax purposes) and $2,840 in 2018 (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, 2020, 2019 or 2018 was not significant. Subsequent to December 31, 2020 and through March 8, 2021, we acquired three businesses approximating $10,522 with $53 liabilities assumed and debt issued of $2,263. The acquired companies are in our Residential and Commercial segment. We do not expect the effect of this acquisition on our consolidated revenues and results of operations to be significant.

Accounts Receivable, Net and Su

Accounts Receivable, Net and Supplemental Balance Sheet Information	12 Months Ended
	Dec. 31, 2020
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, Accounts receivable, net 2020 2019 Accounts receivable $ 214,887 $ 176,849 Unbilled receivables (1) 42,251 58,277 257,138 235,126 Less allowances for credit losses 4,217 3,815 Total $ 252,921 $ 231,311 (1) Unbilled receivables consist of work-in-process in accordance with the terms of contracts, primarily with utility services customers. The following items comprise the amounts included in the balance sheets. Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B: December 31, Other current assets 2020 2019 Refundable income taxes $ — $ 339 Other 778 984 Total $ 778 $ 1,323 December 31, Property and equipment, net 2020 2019 Land and land improvements $ 19,731 $ 19,270 Buildings and leasehold improvements 49,460 44,414 Equipment 623,847 604,211 693,038 667,895 Less accumulated depreciation 488,321 468,045 Total $ 204,717 $ 199,850 December 31, Other assets, noncurrent 2020 2019 Assets invested for self-insurance $ 19,359 $ 15,426 Investment--cost-method affiliate 1,258 1,314 Deferred income taxes 4,167 62 Other 4,972 5,595 Total $ 29,756 $ 22,397 December 31, Accrued expenses 2020 2019 Employee compensation $ 36,108 $ 26,381 Accrued compensated absences 14,534 10,744 Self-insured medical claims 2,065 1,824 Customer advances, deposits 2,067 1,674 Income taxes payable 6,926 6,420 Taxes, other than income 30,354 1,775 Other 6,387 3,613 Total $ 98,441 $ 52,431 December 31, Other liabilities, noncurrent 2020 2019 Pension and retirement plans $ 7,365 $ 6,552 Other 3,324 5,149 Total $ 10,689 $ 11,701

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2020
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 2020 2019 2018 Interest paid $ 7,159 $ 8,463 $ 6,375 Income taxes paid, net 27,494 5,758 11,514 Noncash transactions: Debt issued for purchases of businesses $ 2,472 $ 2,612 $ 2,402 Detail of acquisitions: Assets acquired: Cash $ — $ 3 $ — Accounts receivable 10 2,332 1,311 Operating supplies 22 84 23 Prepaid expense 6 27 89 Equipment 1,932 1,837 4,079 Other assets — 96 7 Intangible assets 3,545 4,067 4,895 Goodwill 5,635 4,174 2,840 Liabilities assumed (613) (1,479) (2,381) Debt issued for purchases of businesses (2,472) (2,612) (2,402) Cash paid $ 8,065 $ 8,529 $ 8,461

Identified Intangible Assets an

Identified Intangible Assets and Goodwill, Net	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Identified Intangible Assets and Goodwill, Net [Text Block]	Intangible Assets and Goodwill, Net The carrying amount of the identified intangible assets and goodwill acquired in connection with our acquisitions were as follows: Weighted-Average December 31, 2020 December 31, 2019 Carrying Accumulated Carrying Accumulated Amortized intangible assets: Customer lists/relationships 3.5 years $ 30,402 $ 22,040 $ 28,301 $ 20,024 Employment-related 2.9 years 9,320 7,755 8,391 7,348 Tradenames 3.9 years 7,938 6,195 7,402 5,788 Amortized intangible assets 47,660 $ 35,990 44,094 $ 33,160 Less accumulated amortization 35,990 33,160 Intangible assets, net $ 11,670 $ 10,934 Goodwill $ 48,256 $ 42,285 The changes in the carrying amounts of goodwill, by segment, for the years ended December 31, 2020 and December 31, 2019 were as follow: Balance at Acquisitions Translation Balance at Utility $ 4,911 $ — $ — $ 4,911 Residential and Commercial 37,374 5,635 336 43,345 Total $ 42,285 $ 5,635 $ 336 $ 48,256 Balance at Acquisitions Translation Balance at Utility $ 4,911 $ — $ — $ 4,911 Residential and Commercial 33,060 4,174 140 37,374 Total $ 37,971 $ 4,174 $ 140 $ 42,285 Future aggregate amortization expense of intangible assets -- The aggregate amortization expense of intangible assets, as of December 31, 2020, in each of the next five years was as follows: Future Amortization Expense Year ending December 31, 2021 $ 2,733 2022 2,502 2023 2,333 2024 1,857 2025 1,284 Thereafter 961 $ 11,670

Short and Long-Term Debt and Co

Short and Long-Term Debt and Commitments Related to Letters of Credit	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 Notes payable $ — $ 1,853 Current portion of long-term debt 19,540 23,302 Current portion of finance leases 2,273 1,348 $ 21,813 $ 26,503 At December 31, 2020, we also had unused short-term lines of credit with several banks totaling $9,168, generally bearing interest 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, 2020 2019 Revolving credit facility Swing-line borrowings $ — $ 10,000 LIBOR borrowings — 52,000 — 62,000 5.09% Senior unsecured notes — 6,000 3.99% Senior unsecured notes 50,000 50,000 4.00% Senior unsecured notes 25,000 25,000 Term loans 21,864 24,076 96,864 167,076 Less debt issuance costs 256 420 Less current portion 19,540 23,302 $ 77,068 $ 143,354 Revolving Credit Facility -- In October 2017, the Company amended and restated its revolving credit facility, as further amended in September 2018, as discussed below. 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. As of December 31, 2020, we had unused commitments under the revolving credit facility approximating $247,123 and $2,877 committed, which consisted of no borrowings and issued letters of credit of $2,877. 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 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 plus .5%. A commitment fee ranging from .10% to .225% is also required based on the average daily unborrowed commitment. 5.09% Senior Unsecured Notes-- On July 22, 2010, we issued 5.09% Senior Unsecured Notes, Series A, (the "5.09% Senior Notes"), in the aggregate principal amount of $30,000 pursuant to a Master Note Purchase Agreement (the “Purchase Agreement”), between the Company and the purchasers of the 5.09% Senior Notes. The 5.09% Senior Notes were due and repaid on July 22, 2020. The 5.09% Senior Notes were equal in right of payment with our revolving credit facility and all other senior unsecured obligations of the Company. Interest was payable semiannually and five equal, annual principal payments commenced on July 22, 2016 (the sixth anniversary of issuance). The Purchase Agreement contained customary events of default and covenants related to limitations on indebtedness and transactions with affiliates and the maintenance of certain financial ratios. 3.99% Senior Unsecured Notes-- On September 21, 2018, we issued 3.99% Senior Notes, Series A (the "3.99% Senior Notes"), in the aggregate principal amount of $50,000. The 3.99% Senior Notes are due September 21, 2028. The 3.99% Senior Notes were issued pursuant to a Note Purchase and Private Shelf Agreement (the “Note Purchase and Shelf Agreement”) between the Company, PGIM, Inc. and the purchasers of the 3.99% Senior Notes. Subsequent series of promissory notes may be issued pursuant to the Note Purchase and Shelf Agreement (the "Shelf Notes") in an aggregate additional principal amount not to exceed $50,000 ($25,000 of which was issued on February 5, 2019). The 3.99% 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 of $10,000 commence on September 21, 2024 (the sixth anniversary of issuance). The Note Purchase and Shelf Agreement contains customary events of default and covenants related to limitations on indebtedness and transactions with affiliates and the maintenance of certain financial ratios. The Company may prepay at any time all, or from time to time any part of, the outstanding principal amount of the 3.99% Senior Notes, subject to the payment of a make-whole amount. In conjunction with the issuance of the 3.99% Senior Notes, on September 21, 2018, the Company entered into an amendment to its revolving credit facility. The amendment amended certain provisions and covenants in the credit agreement to generally conform them to the corresponding provisions and covenants in the Note Purchase and Shelf Agreement. The amendment also permitted the Company to incur indebtedness arising under the Note Purchase and Shelf Agreement in an aggregate principal amount not to exceed $75,000, which included the $50,000 of 3.99% Senior Notes, plus an additional $25,000 in Shelf Notes (which were issued on February 5, 2019). 4.00% Senior Unsecured Notes-- On February 5, 2019, we issued 4.00% Senior Notes, Series B (the "4.00% Senior Notes") pursuant to the Note Purchase and Shelf Agreement in the aggregate principal amount of $25,000. The 4.00% Senior Notes are due September 21, 2028. Subsequent series of Shelf Notes may be issued pursuant to the Note Purchase and Shelf Agreement in an aggregate additional principal amount not to exceed $25,000. A further amendment to the revolving credit facility would be required for such a transaction to be permissible under the revolving credit facility. The 4.00% 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 commence on September 21, 2024. The net proceeds of all senior notes were used to pay down borrowings under our revolving credit facility. Term loans --Periodically, the Company will enter into term loans for the procurement of insurance or to finance acquisitions. Term Loans, Weighted-Average Interest Rate --The weighted-average interest on the term loans approximated 3.89% at December 31, 2020 and 4.02% at December 31, 2019. Aggregate Maturities of Long-Term Debt --Aggregate maturities of long-term debt for the five years subsequent to December 31, 2020 were as follows: 2021--$19,539; 2022--$1,673; 2023--$652; 2024--$15,000; 2025--$15,000; and thereafter $45,000. Accounts Receivable Securitization Facility --In May 2020, the Company amended its Accounts Receivable Securitization Facility (the "AR Securitization program") to extend the scheduled termination date for an additional one year period, to May 18, 2021. In addition to extending the termination date, the amendment included a change to the letter of credit ("LC") issuance fee payable under the terms of the agreement. The AR Securitization program has a limit of $100,000, of which $83,355 and $76,732 were issued for LCs as of December 31, 2020 and December 31, 2019, respectively. Under the AR Securitization program, 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 LCs as of December 31, 2020--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 1.00% 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 program contain various customary representations and warranties, covenants, and default provisions which provide for the termination and acceleration of the commitments under the AR Securitization program 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. Total Commitments Related to Issued Letters of Credit --As of December 31, 2020, total commitments related to issued LCs were $88,242, of which $2,877 were issued under the revolving credit facility, $83,355 were issued under the AR securitization facility and $2,010 were issued under short-term lines of credit. As of December 31, 2019, total commitments related to issued letters of credit were $81,619, of which $2,877 were issued under the revolving credit facility, $76,732 were issued under the AR securitization facility and $2,010 were issued under short-term lines of credit. As of December 31, 2020, we were in compliance with all debt covenants.

Self-Insurance Accruals

Self-Insurance Accruals	12 Months Ended
	Dec. 31, 2020
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 were as follows (Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B): December 31, 2020 2019 Workers' compensation $ 52,060 $ 44,383 Vehicle liability 10,046 12,209 General liability 47,174 39,091 Total 109,280 95,683 Less current portion 37,707 30,882 Noncurrent portion $ 71,573 $ 64,801 The changes in our self-insurance accruals are summarized in the table below. December 31, 2020 2019 Balance, beginning of year $ 95,683 $ 86,884 Provision for claims 51,988 50,854 Payment of claims (38,391) (42,055) Balance, end of year $ 109,280 $ 95,683

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases [Text Block]	LeasesWe lease certain office and parking facilities, warehouse space, equipment, vehicles and information technology equipment under operating leases. Lease expense for these leases is recognized within the Consolidated Statements of Operations on a straight-line basis over the lease term, with variable lease payments recognized in the period those payments are incurred. The following table summarizes the amounts recognized in our Consolidated Balance Sheet related to leases: Consolidated Balance Sheet Classification December 31, December 31, Assets Operating lease assets Right-of-use assets - operating leases $ 55,893 $ 40,033 Finance lease assets Property and equipment, net 8,788 3,183 Total lease assets $ 64,681 $ 43,216 Liabilities Current operating lease liabilities Current portion of operating lease liabilities $ 19,124 $ 14,665 Non-current operating lease liabilities Lease liabilities - operating leases 36,612 25,200 Total operating lease liabilities 55,736 39,865 Current portion of finance lease liabilities Current portion of long-term debt, finance lease liabilities and short-term debt 2,273 1,348 Non-current finance lease liabilities Lease liabilities - finance leases 6,479 1,795 Total finance lease liabilities 8,752 3,143 Total lease liabilities $ 64,488 $ 43,008 The components of lease cost recognized within our Consolidated Statement of Operations were as follows: Year Ended Consolidated Statement December 31, December 31, Operating lease cost Operating expense $ 11,349 $ 6,919 Operating lease cost Selling expense 9,572 8,699 Operating lease cost General and administrative expense 1,115 828 Finance lease cost: Amortization of right-of-use assets Depreciation 2,015 1,371 Interest expense on lease liabilities Interest expense 148 118 Other lease cost (1) Operating expense 5,357 4,211 Other lease cost (1) Selling expense 1,351 1,062 Other lease cost (1) General and administrative expense 52 16 Total lease cost $ 30,959 $ 23,224 (1) Other lease cost includes short-term lease costs and variable lease costs. We often have options to renew lease terms for buildings and other assets. The exercise of lease renewal options is generally at our sole discretion. In addition, certain lease agreements may be terminated prior to their original expiration date at our discretion. We evaluate each renewal and termination option at the lease commencement date to determine if we are reasonably certain to exercise the option on the basis of economic factors. The table below summarizes the weighted average remaining lease term as of December 31, 2020. Operating leases 3.8 years Finance leases 5.4 years The discount rate implicit within our leases is generally not determinable and therefore the Company determines the discount rate based on its incremental borrowing rate. The incremental borrowing rate for each lease is determined based on its term and the currency in which lease payments are made, adjusted for the impacts of collateral. The table below summarizes the weighted average discount rate used to measure our lease liabilities as of December 31, 2020. Operating leases 2.95 % Finance leases 1.88 % Supplemental Cash Flow Information Related to Leases Year Ended December 31, December 31, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (21,786) $ (17,009) Operating cash flows from finance leases (148) (118) Financing cash flows from finance leases (1,996) (1,282) Right-of-use assets obtained in exchange for lease obligations: Operating leases 36,653 56,478 Finance leases 7,664 310 Maturity Analysis of Lease Liabilities As of December 31, 2020 Operating Finance Year ending December 31, 2021 $ 20,427 $ 2,414 2022 16,249 1,527 2023 9,778 1,327 2024 5,434 1,245 2025 2,616 1,151 Thereafter 4,107 1,529 Total lease payments 58,611 9,193 Less interest 2,875 441 Total $ 55,736 $ 8,752

Common Shares, Redeemable Commo

Common Shares, Redeemable Common Shares and Preferred Shares	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Common Shares, Redeemable Common Shares and Preferred Shares [Text Block]	Common Shares, Redeemable Common Shares and Preferred Shares Preferred Shares --We have authorized a class of 4,000,000 preferred shares, no par value, of which none were issued as of December 31, 2020. 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, 2020 was as follows: 2020--5,112,884; 2019--5,146,882; and 2018--5,642,155. 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, 2020 was as follows: 2020--37,800,876; 2019--37,766,878; and 2018--37,271,606. The number of shares in the treasury for each of the three years in the period ended December 31, 2020 was as follows: 2020--20,093,608; 2019--19,736,957; and 2018--20,033,108. 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 M). During 2020, purchases of common shares, both redeemable and common, totaled 1,597,929 shares for $39,079 in cash; we also had direct sales to directors and employees of 17,315 shares for $430, excluding those shares issued through either the exercise of options or the Employee Stock Purchase Plan. We also sold 179,445 shares to our 401(k) plan for $4,376 and issued 420,719 shares to participant accounts to satisfy our liability for the 2019 and 2020 employer match in the amount of $10,282. The liability accrued at December 31, 2020 for the 2020 employer match was $1,800. There were also 393,568 shares purchased during 2020 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 Redeemable Total Shares outstanding, December 31, 2018 17,238,497 5,642,155 22,880,652 Shares purchased (853,738) (746,857) (1,600,595) Shares sold 471,898 251,584 723,482 Stock subscription offering, employee cash purchases 872,390 — 872,390 Options exercised 300,874 — 300,874 Shares outstanding, December 31, 2019 18,029,921 5,146,882 23,176,803 Shares purchased (1,076,028) (521,901) (1,597,929) Shares sold 523,144 487,903 1,011,047 Options exercised 230,231 — 230,231 Shares outstanding, December 31, 2020 17,707,268 5,112,884 22,820,152 On December 31, 2020, we had 22,820,152 common shares outstanding and employee options exercisable to purchase 940,277 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 was required 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 Common shares purchased under the plan were pledged as security for the payment of the promissory note and the common shares were not issued until the promissory note was paid-in-full. Dividends were paid on all subscribed shares, subject to forfeiture to the extent that payment was not ultimately made for the shares. 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 could have been exercised at the rate of one-seventh per year and expired seven years after the date that the right was granted. All rights expired in August 2019. Employees could not exercise a right if they ceased to be employed by the Company.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
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 Defined Accumulated Balance at January 1, 2018 $ (3,305) $ (5,088) $ (8,393) Unrealized gains (losses) (2,514) — (2,514) Amounts reclassified from accumulated other comprehensive income (loss) — 6,291 6,291 Tax effect — (145) (145) Unrecognized amounts from defined benefit pension plans — (279) (279) Tax effect — 6 6 Net of tax amount (2,514) 5,873 3,359 Balance at December 31, 2018 $ (5,819) $ 785 $ (5,034) Unrealized gains (losses) 1,186 — 1,186 Amounts reclassified from accumulated other comprehensive income (loss) — (1,551) (1,551) Tax effect — 143 143 Unrecognized amounts from defined benefit pension plans — (323) (323) Tax effect — 176 176 Net of tax amount 1,186 (1,555) (369) Balance at December 31, 2019 $ (4,633) $ (770) $ (5,403) Unrealized gains (losses) 895 — 895 Amounts reclassified from accumulated other comprehensive income (loss) — 152 152 Tax effect — (39) (39) Unrecognized amounts from defined benefit pension plans — (259) (259) Tax effect — 107 107 Net of tax amount 895 (39) 856 Balance at December 31, 2020 $ (3,738) $ (809) $ (4,547) The amounts reclassified from accumulated other comprehensive income (loss) related to defined benefit pension plans for 2020, 2019 and 2018 are included in net periodic pension expense classified in the statement of operations as general and administrative expense or other income (expense).

The Davey 401KSOP and Employee

The Davey 401KSOP and Employee Stock Ownership Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
The Davey 401KSOP and Employee Stock Ownership Plan [Text Block]	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, 23,040,000 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 Plan. 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, 2020, we amended the 401(k) plan to be a safe harbor 401K plan. Under the amendment, the Company made changes to the hardship provisions and will make quarterly contributions in Company stock equal to, 100% of the first three percent and 50% of the next two percent of each participant's before-tax contributions, subject to IRS limitations, which will be fully vested. This represents a potential maximum contribution of 4%. All nonbargaining domestic employees who attained 21 years of age 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. Our 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 shares based upon our performance and financial condition. 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 $3,298 and $4,749 as of December 31, 2020 and December 31, 2019, respectively. The fair value of the shares held in the Davey 401KSOP and ESOP totaled $150,089 and $119,806 as of December 31, 2020 and December 31, 2019, 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 recorded at fair value, classified as temporary equity in the mezzanine section of the consolidated balance sheets and totaled $153,387 and $124,555 as of December 31, 2020 and December 31, 2019, 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.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [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 has a term of 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. Stock-based compensation expense under all share-based payment plans—our Employee Stock Purchase Plan, stock option plans, stock-settled stock appreciation rights ("SSARs"), and restricted stock units ("RSUs")—included in the results of operations was as follows: Year Ended December 31, 2020 2019 2018 Compensation expense, all share-based payment plans $ 3,407 $ 2,845 $ 3,370 Income tax benefit 538 404 602 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. 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 $1,442 in 2020, $1,118 in 2019 and $998 in 2018. 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 $517 in 2020, $550 in 2019 and $663 in 2018. Stock-Settled Stock Appreciation Rights --A SSAR is an award that allows the recipient to receive common shares equal to the appreciation in the fair value of our common shares between the date the award was granted and the conversion date of the shares vested. Effective January 1, 2019, management and the Compensation Committee replaced the issuance of future SSARs with performance-based RSUs ("PRSUs") for certain management employees. The following table summarizes the SSARs as of December 31, 2020: Stock-Settled Number of Weighted- Weighted- Unrecognized Aggregate Unvested, January 1, 2020 262,705 $ 3.47 Granted — — Forfeited (2,254) 3.53 Vested (155,215) 3.29 Unvested, December 31, 2020 105,236 $ 3.73 1.6 years $ 241 $ 2,620 Compensation costs for SSARs are determined using a fair-value method and amortized over the requisite service period. “Intrinsic value” is defined as the amount by which the fair market value of a common share exceeds the grant date price of a SSAR. Compensation expense for SSARs totaled $282 in 2020, $363 in 2019 and $540 in 2018. Restricted Stock Units --During the year ended December 31, 2020, the Compensation Committee of the Board of Directors awarded 86,959 PRSUs to certain management employees and 11,904 RSUs to nonemployee directors. The Compensation Committee made similar awards in prior periods. The awards vest over specified periods. The following table summarizes PRSUs and RSUs as of December 31, 2020: Restricted Stock Units Number of Weighted- Weighted- Unrecognized Aggregate Unvested, January 1, 2020 224,259 $ 17.11 Granted 98,863 23.74 Forfeited (1,871) 17.37 Vested (65,944) 15.52 Unvested, December 31, 2020 255,307 $ 20.09 2.4 years $ 2,778 $ 6,357 Employee PRSUs 220,157 $ 19.92 2.7 years $ 2,403 $ 5,482 Nonemployee Director RSUs 35,150 $ 21.14 1.4 years $ 375 $ 875 Compensation cost for PRSUs and RSUs is determined using a fair-value method and amortized on the straight-line recognition method over the requisite service period. “Intrinsic value” is defined as the amount by which the fair market value of a common share exceeds the grant date price of a PRSUs or an RSUs . Compensation expense on PRSUs and RSUs totaled $1,166 in 2020, $814 in 2019 and $1,169 in 2018. The fair value of each stock-based 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. 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, 2020 2019 2018 Volatility rate 9.7 % 9.9 % 10.1 % Risk-free interest rate .7 % 2.3 % 2.7 % Expected dividend yield .4 % .7 % .7 % Expected life of awards (years) 8.1 8.8 9.2 General Stock Option Information --The following table summarizes activity under the stock option plans for the year ended December 31, 2020: Stock Options Number of Weighted- Weighted- Unrecognized Aggregate Outstanding, January 1, 2020 1,428,082 $ 15.13 Granted 174,897 24.20 Exercised (166,675) 11.30 Forfeited (27,645) 16.79 Outstanding, December 31, 2020 1,408,659 $ 16.67 5.6 years $ 1,298 $ 11,593 Exercisable, December 31, 2020 940,277 $ 14.54 4.3 years $ 9,743 “Intrinsic value” is defined as the amount by which the market price of a common share exceeds the exercise price of an option. Information regarding the stock options outstanding at December 31, 2020 is summarized below: Stock Options Number Weighted-Average Weighted- Number Weighted- Employee options: $ 11.60 212,480 2.5 years $ 11.60 212,480 $ 11.60 13.20 240,084 3.5 years 13.20 240,084 13.20 15.05 191,265 4.5 years 15.05 191,265 15.05 16.35 210,165 5.5 years 16.35 159,165 16.35 17.60 121,550 6.5 years 17.60 73,650 17.60 19.10 127,950 7.5 years 19.10 42,000 19.10 21.10 26,500 8.2 years 21.10 4,260 21.10 21.10 112,068 8.5 years 21.10 17,373 21.10 24.20 28,397 9.5 years 24.20 — 24.20 24.20 138,200 9.2 years 24.20 — 24.20 1,408,659 5.6 years $ 16.67 940,277 $ 14.54 We issue common shares from treasury upon the exercise of stock options, SSARs, PRSUs, RSUs 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: $538 in 2020, $404 in 2019, and $602 in 2018. 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) SSARs are exercised; (b) PRSUs and RSUs 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: $530 in 2020, $1,181 in 2019, and $453 in 2018.

Defined Benefit Pension Plans

Defined Benefit Pension Plans	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Defined Benefit Pension Plans [Text Block]	Defined Benefit Pension Plans We have two defined benefit pension plans covering certain current and retired U.S. employees. Plans include: (i) a Supplemental Executive Retirement Plan (“SERP”) for which future benefit accruals were frozen effective at the end of the second quarter 2015; and (ii) 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 nonqualified supplemental pension benefits will be paid, 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 Restoration Plan. In connection with the freeze of the Restoration Plan and the SERP, all 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 Restoration Plan and (ii) the 2015 freeze of the SERP. During the second quarter of 2019, the Company terminated its Employee Retirement Plan (“ERP”) for employees hired prior to January 1, 2009 and for which future benefits were frozen effective December 31, 2008. We purchased a group annuity contract from a third-party insurance company which unconditionally and irrevocably guarantees the full-payment of all annuity payments to the remaining 231 participants in our ERP. The agreement transferred all remaining ERP benefit obligations to the third-party insurance company, resulting in a pretax actuarial settlement loss of $1,677. The change in benefit obligations and the fair value of plans assets follows: December 31, 2020 2019 Change in benefit obligation Projected benefit obligation at beginning of year $ 3,265 $ 7,064 Service cost — 45 Interest cost 105 170 Actuarial (gains)/losses 259 323 Settlements — (1,677) Benefits paid (158) (2,660) Projected benefit obligation at end of year $ 3,471 $ 3,265 Accumulated benefit obligation at end of year $ 3,471 $ 3,265 December 31, 2020 2019 Change in fair value of plan assets Fair value of plan assets at beginning of year $ — $ 3,758 Employer contributions 158 579 Settlements — (1,677) Benefits paid (158) (2,660) Fair value of plan assets at end of year $ — $ — With the termination of the ERP plan, future benefit payments made to participants under the remaining SERP and Restoration Plan are made from the Company's general assets. December 31, 2020 2019 Funded status of the plans Fair value of plan assets $ — $ — Projected benefit obligation 3,471 3,265 Funded status of the plans $ (3,471) $ (3,265) December 31, 2020 2019 Funded status by plan SERP $ (3,019) $ (2,833) Restoration Plan (452) (432) Funded status of the plans $ (3,471) $ (3,265) December 31, 2020 2019 Amounts reported in the consolidated balance sheets Current liability $ (203) $ (202) Noncurrent liability (3,268) (3,063) Funded status of the plans $ (3,471) $ (3,265) Amounts included in accumulated other comprehensive income (loss), related to our defined benefit pension plans follow: At December 31, 2020 At December 31, 2019 Pretax Net of Tax Pretax Net of Tax Amounts reported in accumulated other comprehensive income Unrecognized net actuarial loss $ 892 $ 737 $ 723 $ 638 Unrecognized prior service cost 87 72 150 132 Amounts reported in accumulated other comprehensive income $ 979 $ 809 $ 873 $ 770 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 2021 follows: Year ending December 31, 2021 Pretax Net of Tax Amortization of Costs Expected to be Recognized Next Year Unrecognized net actuarial loss $ 138 $ 100 Unrecognized prior service cost 63 46 Amortization of Costs Expected to be Recognized Next Year $ 201 $ 146 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, 2020 2019 For pension plans with accumulated benefit obligations in excess of plan assets Projected benefit obligation $ 3,471 $ 3,265 Accumulated benefit obligation 3,471 3,265 Fair value of plan assets — — The discount rates used to measure the year-end benefit obligation and compute pension expense for the subsequent year were: December 31, 2020 2019 2018 Actuarial assumptions - Discount Rate SERP 3.34 % 3.34 % 4.37 % Restoration Plan 3.23 % 3.23 % 4.28 % Net periodic benefit expense (income) associated with the defined benefit pension plans included the following components: Year Ended December 31, 2020 2019 2018 Components of pension expense (income) Service costs--increase in benefit obligation earned $ — $ 75 $ 400 Interest cost on projected benefit obligation 105 198 718 Expected return on plan assets — (59) (231) Settlement loss — 1,677 5,499 Amortization of net actuarial loss 89 87 728 Amortization of prior service cost 64 64 64 Net pension expense of defined benefit pension plans $ 258 $ 2,042 $ 7,178 Expected Benefit Plan Payments --The benefits, as of December 31, 2020, 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, follows: Participants Benefits Estimated future payments Year ending December 31, 2021 $ 205 2022 202 2023 198 2024 194 2025 189 Years 2026 to 2030 988 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. Pension Fund EIN/Pension Pension FIP/RP Davey Tree Surcharge Expiration 2020 2019 2020 2019 2018 National Electric 53-0181657/001 Green Green No $ 3,239 $ 904 $ 768 No Ranging from December 31, 2020 to Eighth District 84-6100393/001 Green Green No 161 190 142 No December 31, 2023 $ 3,400 $ 1,094 $ 910 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 twelve collective-bargaining agreements with the National Electric Benefit Fund, with expiration dates ranging from December 31, 2020 to December 31, 2023, and one collective-bargaining agreement with Eighth District Electrical Pension Fund which expires on December 21, 2023. Expired agreements are currently being renegotiated.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On March 27, 2020, Congress approved and the President signed the Coronavirus Aid, Relief, and Economic Security ("CARES") Act into law. The CARES Act is a tax-and-spending package intended to provide economic relief to address the impact of the COVID-19 pandemic. After evaluating several significant business tax provisions, such as net operating losses and employee retention credits, the Company has determined that there is no significant impact on the Company. Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B. Income (loss) before income taxes was attributable to the following sources: Year Ended December 31, 2020 2019 2018 United States $ 82,382 $ 54,569 $ 36,624 Canada 1,500 (891) 119 Total $ 83,882 $ 53,678 $ 36,743 The provision for income taxes follows: Year Ended December 31, 2020 2019 2018 Current provision (benefit): Federal $ 22,093 $ 7,934 $ 3,165 State 6,260 3,624 2,290 Canadian (50) (328) 50 Total current 28,303 11,230 5,505 Deferred taxes (5,358) 1,398 3,880 Total taxes on income $ 22,945 $ 12,628 $ 9,385 A reconciliation of the expected statutory U.S. federal rate to our actual effective income tax rate follows: Year Ended December 31, 2020 2019 2018 Statutory U.S. federal tax rate 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit 5.2 5.6 5.7 Effect of Canadian income taxes .2 — .1 Nondeductible expenses 1.3 2.2 2.1 Stock compensation (.3) (1.8) (.7) ESOP dividend deduction (.1) (.2) (.3) Uncertain tax adjustments and audit settlement .1 .2 (3.8) Pension termination — (2.9) — All other, net — (.7) 1.4 Effective income tax rate 27.4 % 23.4 % 25.5 % 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. Significant components of our noncurrent net deferred tax assets and liabilities at December 31, were as follows: December 31, 2020 2019 Deferred tax assets: Self-insurance accruals $ 22,847 $ 20,120 Accrued compensated absences 1,876 1,389 Accrued expenses and other liabilities 942 841 Accrued stock compensation 2,105 1,906 Foreign tax credit carryforward 1,597 2,137 Other future deductible amounts, net 4,076 4,167 33,443 30,560 Less deferred tax asset valuation allowance 1,185 1,683 32,258 28,877 Deferred tax liabilities: Intangibles 1,407 1,065 Prepaid expenses 4,243 3,701 Property and equipment 22,441 24,049 28,091 28,815 Net deferred tax asset--noncurrent $ 4,167 $ 62 We treat all of our Canadian subsidiary earnings through December 31, 2020 as permanently reinvested and have not provided any U.S. federal or state tax thereon. As of December 31, 2020, approximately $29,390 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, 2020, we recorded a valuation allowance on foreign tax credit carryforwards that arose due to the transition toll tax on the deemed repatriation of deferred foreign earnings of non-U.S. operations due to the Tax Cuts and Jobs Act. Management presently believes that it is more-likely-than-not that the deferred tax asset, related to the foreign tax credits that expire in 2027, will not be fully 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. The balance of unrecognized benefits and the amount of related interest and penalties at December 31, were as follows: December 31, 2020 2019 Unrecognized tax benefits $ 1,183 $ 1,850 Portion, if recognized, would reduce tax expense and effective tax rate 735 654 Accrued interest on unrecognized tax benefits 72 64 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. With the exception of U.S. state jurisdictions and Canada, the Company is no longer subject to examination by tax authorities for the years through 2016. As of December 31, 2020, 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, 2020 2019 2018 Balance, beginning of year $ 1,850 $ 1,325 $ 2,581 Additions based on tax positions related to the current year — 547 224 Reductions based on tax positions related to the current year (187) — — Additions for tax positions of prior years 101 23 20 Reductions for tax positions of prior years — — (1,500) Lapses in statutes of limitations (581) (45) — Balance, end of year $ 1,183 $ 1,850 $ 1,325

Earnings Per Share Information

Earnings Per Share Information	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Share Information [Text Block]	Earnings Per Share Information Earnings per share is computed as follows: Year Ended December 31, 2020 2019 2018 Income available to common shareholders: Net income $ 60,937 $ 41,050 $ 27,358 Weighted-average shares: Basic: Outstanding 21,981,950 22,906,264 23,698,478 Partially-paid share subscriptions — — 690,260 Basic weighted-average shares 21,981,950 22,906,264 24,388,738 Diluted: Basic from above 21,981,950 22,906,264 24,388,738 Incremental shares from assumed: Exercise of stock subscription purchase rights — 54,961 141,287 Exercise of stock options and awards 1,051,136 1,016,864 950,593 Diluted weighted-average shares 23,033,086 23,978,089 25,480,618 Share data: Earnings per share--basic $ 2.77 $ 1.79 $ 1.12 Earnings per share--diluted $ 2.65 $ 1.71 $ 1.07 Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B

Operations by Business Segment

Operations by Business Segment and Geographic Information	12 Months Ended
	Dec. 31, 2020
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 and rights-of-way and chemical brush control, 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. 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 Residential All Reconciling Consolidated Fiscal Year 2020 Revenues $ 739,118 $ 545,357 $ 3,077 $ — $ 1,287,552 Income (loss) from operations 73,592 53,623 (25,297) (7,717) (a) 94,201 Interest expense (6,899) (6,899) Interest income 2,135 2,135 Other income (expense), net (5,555) (5,555) Income before income taxes $ 83,882 Depreciation $ 27,545 $ 23,553 $ — $ 2,790 (b) $ 53,888 Amortization 530 2,297 — — 2,827 Capital expenditures 22,595 21,327 — 7,728 51,650 Segment assets, total 280,467 238,876 — 136,011 (c) 655,354 Fiscal Year 2019 Revenues $ 607,556 $ 534,655 $ 1,509 $ — $ 1,143,720 Income (loss) from operations 37,696 52,471 (12,963) (7,248) (a) 69,956 Interest expense (8,514) (8,514) Interest income 348 348 Other income (expense), net (8,112) (8,112) Income before income taxes $ 53,678 Depreciation $ 30,304 $ 23,537 $ — $ 3,451 (b) $ 57,292 Amortization 474 2,071 — — 2,545 Capital expenditures 26,528 24,573 — 7,564 58,665 Segment assets, total 267,982 226,313 — 102,629 (c) 596,924 Fiscal Year 2018 Revenues $ 537,484 $ 486,005 $ 1,302 $ — $ 1,024,791 Income (loss) from operations 32,370 47,812 (20,569) (4,676) (a) 54,937 Interest expense (7,039) (7,039) Interest income 350 350 Other income (expense), net (11,505) (11,505) Income before income taxes $ 36,743 Depreciation $ 29,526 $ 21,720 $ — $ 3,668 (b) $ 54,914 Amortization 211 1,842 — 2 2,055 Capital expenditures 32,148 22,256 — 6,006 60,410 Segment assets, total 239,426 208,369 — 78,828 (c) 526,623 Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B Reconciling adjustments from segment reporting to consolidated external financial reporting include unallocated corporate items: (a) 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, 2020 2019 2018 Revenues United States $ 1,214,628 $ 1,066,035 $ 949,317 Canada 72,924 77,685 75,474 $ 1,287,552 $ 1,143,720 $ 1,024,791 December 31, 2020 2019 2018 Long-lived assets, net United States $ 324,776 $ 288,196 $ 251,181 Canada 25,516 27,303 20,374 $ 350,292 $ 315,499 $ 271,555

Revenue Recognition (Notes)

Revenue Recognition (Notes)	12 Months Ended
	Dec. 31, 2020
Revenue Recognition [Abstract]
Revenue from contracts with customers [Text Block]	Revenue Recognition We recognize revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers. Nature of Performance Obligations and Significant Judgments At contract inception, the Company assesses the goods and services promised in its contracts with customers and identifies a performance obligation for each promised good or service (or bundle of goods and services) that is distinct. To identify the performance obligations, the Company considers all of the goods or services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. A description of our performance obligations is included below. • Residential and Commercial Services - We provide a wide array of services for our residential and commercial customers including the treatment, preservation, maintenance, removal and planting of trees, shrubs and other plant life, landscaping, grounds maintenance, the application of fertilizer, herbicides and insecticides, natural resource management and consulting, forestry research and development, and environmental planning. A contract with a customer may include only one of these services, all of these services, or a combination of these services. For contracts in which we provide all, or a combination of, these services, we believe that the nature of our promise is to provide an integrated property management service for our customer. In these contracts, the customer has effectively outsourced the care and maintenance of its property grounds to us during the duration of the contract as we are responsible for providing a continuous delivery of outsourced maintenance activities over the contract term. As such, for contracts that contain a combination of services, we have concluded that we have a single performance obligation, which is accounted for as a series of distinct services. • Utility Services - We provide a suite of vegetation management or arboricultural 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 and rights-of-way, chemical brush control, natural resource management and consulting, forestry research and development, and environmental planning. A contract with a customer may include only one of these services, all of these services, or a combination of these services. For contracts in which we provide all, or a combination of, these services, we believe that the nature of our promise is to provide an integrated overall vegetation management service, rather than the performance of discrete activities or services for the customer. As such, for contracts that contain a combination of services, we have concluded that we have a single performance obligation, which is accounted for as a series of distinct services. Our contracts with our customers generally originate upon the completion of a quote for services for residential and commercial customers or the receipt of a purchase order (or similar work order) for utility customers. In some cases, our contracts are governed by master services agreements, in which case our contract under ASC 606 consists of the combination of the master services agreement and the quote/purchase order. Many of our contracts have a stated duration of one year or less or contain termination clauses that allow the customer to cancel the contract after a specified notice period, which is typically less than 90 days. Due to the fact that many of our arrangements allow the customer to terminate for convenience, the duration of the contract for revenue recognition purposes generally does not extend beyond the services that we have actually transferred. As a result, many of our contracts are, in effect, day-to-day or month-to-month contracts. Revenue from our residential, commercial, and utility performance obligations is recognized over time as the customer simultaneously receives and consumes the benefits of our services as we perform them. Many of our contracts compensate us based on an agreed upon price for each increment of service provided to the customer. Therefore, revenue is mainly recognized as each increment of service is provided to the customer at the amount that we are contractually entitled to. For contracts that contain a fixed price, we generally use a units-delivered based output method to measure progress. Revenue from our consulting services is also recognized over time and we use a cost-based input method to measure progress. Payment for our services is generally due within 30 days of such services being provided to the customer. The transaction price for our contracts is determined upon establishment of the contract that contains the final terms of the sale, including the description, quantity, and price of each service purchased. Certain of our contracts contain variable consideration, including index-based pricing, chargebacks, and prompt payment discounts. The Company estimates variable consideration and performs a constraint analysis for these contracts on the basis of both historical information and current trends. However, these types of variable consideration do not have a material effect on the Company’s revenue, either individually or in the aggregate. In addition, although our contracts generally include fixed pricing for each increment of service, the ultimate quantity of services that will be required in order to fulfill our performance obligations is unknown at contract inception. Therefore, our total transaction price ultimately varies based on the quantity and types of services provided to our customer. However, this type of variable consideration is allocated entirely to the distinct services within the series to which it relates. Disaggregation of Revenue The following tables disaggregate our revenue for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 by major sources: Year Ended December 31, 2020 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 535,260 $ 318,061 $ 61 $ 853,382 Grounds maintenance — 138,885 — 138,885 Storm damage services 20,907 9,724 — 30,631 Consulting and other 182,951 78,687 3,016 264,654 Total revenues $ 739,118 $ 545,357 $ 3,077 $ 1,287,552 Geography: United States $ 703,324 $ 508,227 $ 3,077 $ 1,214,628 Canada 35,794 37,130 — 72,924 Total revenues $ 739,118 $ 545,357 $ 3,077 $ 1,287,552 Year Ended December 31, 2019 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 448,325 $ 305,365 $ (108) $ 753,582 Grounds maintenance — 152,283 — 152,283 Storm damage services 3,096 4,905 — 8,001 Consulting and other 156,135 72,102 1,617 229,854 Total revenues $ 607,556 $ 534,655 $ 1,509 $ 1,143,720 Geography: United States $ 567,134 $ 497,392 $ 1,509 $ 1,066,035 Canada 40,422 37,263 — 77,685 Total revenues $ 607,556 $ 534,655 $ 1,509 $ 1,143,720 Year Ended December 31, 2018 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 394,481 $ 290,940 $ (1,520) $ 683,901 Grounds maintenance — 117,498 — 117,498 Storm damage services 13,864 9,447 — 23,311 Consulting and other 129,139 68,120 2,822 200,081 Total revenues $ 537,484 $ 486,005 $ 1,302 $ 1,024,791 Geography: United States $ 499,242 $ 448,773 $ 1,302 $ 949,317 Canada 38,242 37,232 — 75,474 Total revenues $ 537,484 $ 486,005 $ 1,302 $ 1,024,791 Contract Balances Our contract liabilities consist of advance payments, billings in excess of costs incurred and deferred revenue. The Company has recognized $1,530 and $2,230 of revenue for the twelve months ended December 31, 2020 and December 31, 2019, respectively, that was included in the contract liability balance at December 31, 2019 and December 31, 2018, respectively. Net contract liabilities consisted of the following: December 31, December 31, Contract liabilities - current $ 3,242 $ 3,129 Contract liabilities - noncurrent 1,754 2,705 Net contract liabilities $ 4,996 $ 5,834 Practical Expedients & Accounting Policy Elections • Remaining performance obligations - The Company’s contracts for service revenue have an original duration of one year or less. Therefore, because of the short duration of these contracts, the Company has not disclosed the transaction price for the future performance obligations as of the end of each reporting period or when the Company expects to recognize this revenue. • Incremental costs of obtaining a contract - The Company’s contracts for service revenue have an original duration of one year or less. Therefore, the Company has elected to expense these costs as incurred. • Right to invoice - For the Company’s contracts in which it has the right to invoice the customer on the basis of actual work performed (i.e., output), the Company has elected to measure the satisfaction of performance obligation(s) on the basis of actual work performed, as the invoiced amount directly corresponds to the value transferred to the customer. • Sales taxes - The Company has, as an accounting policy election, decided to exclude from the measurement of the transaction price all sales taxes assessed by a governmental authority. • Significant financing component - The Company’s contracts do not allow for payment terms which exceed one year, and thus need not account for the effects of a significant financing component.

Fair Value Measurements and Fin

Fair Value Measurements and Financial Instruments	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value measurements and financial instruments	Fair Value Measurements and Financial Instruments FASB ASC 820, “Fair Value 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. Our assets and liabilities measured at fair value on a recurring basis at December 31, 2020 and December 31, 2019, were as follows: Fair Value Measurements at December 31, 2020 Using: Total Quoted Significant Significant Description December 31, 2020 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 19,359 $ 19,359 $ — $ — Liabilities: Deferred compensation $ 3,192 $ — $ 3,192 $ — Fair Value Measurements at December 31, 2019 Using: Total Quoted Significant Significant Description December 31, 2019 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 15,402 $ 15,402 $ — $ — Liabilities: Deferred compensation $ 2,786 $ — $ 2,786 $ — The assets invested for self-insurance are certificates of deposits--classified as Level 1--based on quoted market prices of the identical underlying securities in active markets. 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. 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. Financial instruments classified as noncurrent liabilities and their carrying values and fair values were as follows: December 31, 2020 December 31, 2019 Carrying Fair Carrying Fair Revolving credit facility, noncurrent $ — $ — $ 62,000 $ 62,000 Senior unsecured notes 75,000 81,424 75,000 79,558 Term loans, noncurrent 2,324 2,451 6,774 7,124 Total $ 77,324 $ 83,875 $ 143,774 $ 148,682 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, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Letters of Credit At December 31, 2020, we were contingently liable to our principal banks in the amount of $88,242 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 accruals 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 record a legal accrual, consistent with applicable accounting guidance. Based on information currently available to us, advice of counsel, and available insurance coverage, we believe that our established accruals 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 accruals. 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. In November 2017, a suit was filed in Savannah, Georgia state court (“State Court”) against Davey Tree, its subsidiary, Wolf Tree, Inc. ("Wolf Tree"), a former Davey employee, two Wolf Tree employees, and a former Wolf Tree 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, who was shot and killed in August 2017. In July 2018, a related survival action was filed by the deceased’s estate against Davey Tree, its subsidiary, Wolf Tree, and four current and former employees in Savannah, Georgia, which arises out of the same allegations, seeks compensatory and punitive damages and also includes three Racketeer Influenced and Corrupt Organizations Act ("RICO") claims under Georgia law seeking compensatory damages, treble damages, and punitive damages. The 2018 case was removed to the United States District Court for the Southern District of Georgia, Savannah Division ("Federal Court"), on August 2, 2018. The Company filed a motion to dismiss the RICO claims. Plaintiffs filed a motion to remand the case to state court, which the Company has opposed. The cases were mediated unsuccessfully in December 2018 and the State Court case was originally set for trial on January 22, 2019. However, as discussed below, all of the civil cases were later stayed on December 28, 2018 until the conclusion of criminal proceedings against individuals and currently remain stayed. On December 6, 2018, a former Wolf Tree employee pled guilty to conspiracy to conceal, harbor, and shield illegal aliens. On December 21, 2018, the United States federal prosecutors filed a motion to stay both actions on the grounds that on December 13, 2018, an indictment was issued charging two former Wolf Tree employees and one other individual with various crimes, including conspiracy to murder the deceased. On December 17, 2018, the United States Attorney’s Office for the Southern District of Georgia informed the Company and Wolf Tree that they are also under investigation for potential violations of immigration and other laws relating to the subject matter of the ongoing criminal investigation referenced above. The Company and Wolf Tree are cooperating with the investigation and have met with both the civil and criminal divisions of the Department of Justice ("DOJ") to resolve the matter. Due to pandemic-related issues and delays on the side of the DOJ, the matter currently remains unresolved. On December 28, 2018, the State Court granted the United States’ motion to stay but indicated that it would nonetheless consider certain pending matters, including: (1) Plaintiff and a co-defendant’s motions that Davey Tree be forced to produce privileged documents and testimony, which had been submitted to a Special Master for recommendation; and (2) the Defendants’ motions for summary judgment. On January 11, 2019, the Special Master issued his recommendation that both Plaintiff and the co-defendant’s motions to force Davey to disclose privileged information be denied. The State Court judge has not yet moved on the recommendation. On January 29, 2019, the State Court heard oral argument on Defendants’ motions for summary judgment, and the motions remain pending during the stay of the cases. On January 28, 2019, the Federal Court also granted the United States’ motion to stay. On January 29, 2019, the State Court ordered the parties to return to mediation, which occurred on April 17, 2019 but was unsuccessful in resolving the matters. All civil cases continue to remain stayed. In both cases, the Company has denied all liability and is vigorously defending the action. It also has retained separate counsel for some of the individual defendants, each of whom has denied all liability and also is vigorously defending the action. PG&E Bankruptcy Filing On January 29, 2019, Pacific Gas & Electric Company, and its parent company PG&E Corporation, our largest utility customer, filed voluntary bankruptcy petitions under Chapter 11 of the United States Bankruptcy Code in the U.S. Bankruptcy Court for the Northern District of California. PG&E accounted for approximately 12% of revenues during 2019, and 12% in 2018. As a utility company, PG&E serves residential and industrial customers in California and has an ongoing obligation to continue to serve its customers, and we continue to perform under our contracts with PG&E post-petition. As of the date of the bankruptcy filing, we had pre-petition accounts receivable of approximately $15,000. On July 1, 2020, PG&E emerged from Chapter 11, successfully completing its restructuring process and implementing its Plan of Reorganization ("the Plan"). Davey Tree has been paid in full on all amounts outstanding, including interest accrued on the past amounts due at the federal judgment rate. Further, Davey Tree's primary contracts were assumed by PG&E. Due to PG&E’s implementation of the Plan, we do not anticipate PG&E's bankruptcy will have a material impact on our future cash flows or results of operations. Northern California Wildfires On October 7, 2019 and October 8, 2019, four lawsuits were filed against multiple vegetation management contractors to PG&E, including Davey Tree, for damages resulting from the Northern California wildfires. The filing dates - exactly two years after the start of the fires - suggest that these lawsuits were intended to preserve any claims that might otherwise have become barred by the applicable statute of limitations. Davey Tree has been served with only one of the four complaints, in the case of Quinisha Kyree Abram v. ACRT, Inc., et. al, Case No. CGC-19-579861 filed in the Superior Court of the State of California, County of San Francisco (the “ Abram case”). Davey Tree has filed a demurrer and motion to dismiss the Abram case, which has not yet been heard by the court. The Abram case has been stayed by the court until July 29, 2021. In addition, a fifth action was brought against Davey Tree in Napa County Superior Court, entitled Donna Walker, et al. v. Davey Tree Surgery Company, et. al, Case No. 19CV001194, on August 8, 2019 (the " Walker Case"). Davey Tree filed a demurrer and motion to dismiss the Walker case, which has not yet been heard by the court. The Walker case has been stayed by the court until April 21, 2021. In the PG&E bankruptcy, the official Tort Claimants’ Committee, representing wildfire victims and other claimants, served subpoenas related to the Northern California wildfires on numerous contractors of PG&E, including Davey Tree Surgery Company, Davey Resource Group, and Davey Tree, to which we responded. In the PG&E bankruptcy, the Plan was confirmed on June 20, 2020 and became effective on July 1, 2020. The Plan created and assigned certain claims against PG&E’s contractors, including Davey Tree and its subsidiaries, to a Fire Victim Trust. On January 28, 2021, John K. Trotter, Jr., in his capacity of the Trustee of the PG&E Fire Victim Trust, filed three additional lawsuits in San Francisco County Superior Court naming Davey Tree and its subsidiaries, Davey Tree Surgery Company and Davey Resource Group, Inc., among other contractors. The suits allege that Davey Tree and its subsidiaries are liable under the claims assigned by PG&E to the Fire Victim Trust. In total there are eight pending lawsuits related to the 2017 Northern California Fires filed against Davey Tree and various other contractors. In all of the foregoing actions related to the Northern California fires, the Company intends to deny all liability and vigorously defend the actions.

Quarterly Results of Operations

Quarterly Results of Operations	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited) [Text Block]	Quarterly Results of Operations (Unaudited) The following is a summary of the results of operations for each quarter of 2020 and 2019. Fiscal 2020, Three Months Ended Mar 28 June 27 Sept 26 Dec 31 Revenues $ 288,280 $ 319,247 $ 337,453 $ 342,572 Gross profit (revenues less costs and expenses, operating) 89,675 128,265 128,815 117,500 Income from operations 3,722 44,389 35,372 10,718 Net income (loss) (21) 29,881 24,535 6,542 Net income (loss) per share -- Basic $ — $ 1.31 $ 1.07 $ .39 Net income (loss) per share -- Diluted $ — $ 1.25 $ 1.03 $ .37 ESOT valuation per share $ 24.20 $ 24.90 $ 24.90 $ 30.00 Fiscal 2019, Three Months Ended Mar 30 June 29 Sept 28 Dec 31 Revenues $ 247,889 $ 301,434 $ 307,473 $ 286,924 Gross profit (revenues less costs and expenses, operating) 81,720 113,662 114,280 103,962 Income from operations 2,813 30,288 22,727 14,128 Net income (loss) (593) 19,729 13,397 8,516 Net income (loss) per share -- Basic $ (.03) $ .86 $ .59 $ .37 Net income (loss) per share -- Diluted $ (.03) $ .82 $ .56 $ .35 ESOT valuation per share $ 21.10 $ 22.60 $ 22.60 $ 24.20 Certain amounts in prior quarters and prior years have been recast as a result of the change in accounting principle as discussed in Note B Fourth quarters of 2020 and 2019 include adjustments to casualty insurance expense that had the effect of increasing gross profit in 2020 by $915 and decreasing gross profit in 2019 by $2,077.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
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 and certain prior-year amounts have been reclassified to conform to the current year presentation. In addition, our financial statements and corresponding footnotes for prior periods have been recast to reflect the retrospective application of the change in accounting principle discussed in the Self-Insurance Accruals section of this note.
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, stock valuation and revenue recognition. Actual results could differ from those estimates. While the coronavirus ("COVID-19") pandemic did not have a material adverse effect on our reported results for our fiscal year, the overall extent and duration of the impact of COVID-19 on businesses and economic activity generally remains unclear. The extent to which our operations may be impacted by COVID-19 will depend largely on future developments, which are highly uncertain due to its continual evolution, such as the previous resurgences in cases and the emergence of new strains of COVID-19, and cannot be accurately predicted, including new information which may emerge concerning the severity of the outbreak and actions by government authorities to
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 20 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 year to seven 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 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. Our annual impairment assessment date has been designated as the first day of our fourth fiscal 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, not to exceed the carrying value of the goodwill allocated to that reporting unit. We conducted our annual impairment tests and determined that no impairment loss was required to be recognized in 2020 or for any prior periods. There were no events or circumstances from the date of our assessment through December 31, 2020 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. Self-insurance accruals consist of the projected settlement value of reported and unreported claims. 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. Estimating ultimate losses of reported and unreported claims is subject to a high degree of variability as it involves complex estimates that are generally derived using a variety of actuarial estimation techniques and numerous assumptions and expectations about future events, many of which are highly uncertain. 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. 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. Changes in claims incurred, claim severity, or other estimates and judgments used by management could have a material impact on the amount and timing of expense for any period. During the year ended December 31, 2020, we changed our method of accounting for our workers' compensation accruals from measuring the liabilities on a discounted basis to an undiscounted basis. We believe that measuring the workers' compensation accruals on an undiscounted basis is preferable because it simplifies the accounting for the liabilities, provides consistency with our other lines of coverage (vehicle liability and general liability) and results in financial statement presentation consistent with our industry peers.
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 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 --We recognize revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers. See Note S for a detailed description of our revenue recognition policy.
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 are as 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 17% of revenues during 2020, 12% in 2019 and 12% in 2018. To reduce credit risk, we evaluate the credit
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 converted 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.
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 accruals 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 record a legal accrual, consistent with applicable accounting guidance.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
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 20 years Leasehold improvements Shorter of lease term or estimated useful life; ranging from 5 to 20 years December 31, Property and equipment, net 2020 2019 Land and land improvements $ 19,731 $ 19,270 Buildings and leasehold improvements 49,460 44,414 Equipment 623,847 604,211 693,038 667,895 Less accumulated depreciation 488,321 468,045 Total $ 204,717 $ 199,850
Change in accounting principle	The following tables present the effects of the change in accounting principle to our financial statements: December 31, 2019 Balance Sheets Prior to Change in Accounting Principle Effect of Change Recast Self-insurance accruals (long term) $ 62,113 $ 2,688 $ 64,801 Other assets (noncurrent) 22,335 62 22,397 Other liabilities (long term) 12,268 (567) 11,701 Retained earnings 179,770 (2,059) 177,711 December 31, 2019 December 31, 2018 Statement of Operations Prior to Change in Accounting Principle Effect of Change Recast Prior to Change in Accounting Principle Effect of Change Recast Operating expense $ 730,507 $ (411) $ 730,096 $ 665,388 $ 753 $ 666,141 Income from operations 69,545 411 69,956 55,690 (753) 54,937 Income before income taxes 53,267 411 53,678 37,496 (753) 36,743 Income tax expense 12,470 158 12,628 9,519 (134) 9,385 Net income (loss) 40,797 253 41,050 27,977 (619) 27,358 Net income per share: Basic 1.78 0.01 1.79 1.15 (0.03) 1.12 Diluted 1.70 0.01 1.71 1.10 (0.03) 1.07 December 31, 2019 December 31, 2018 Cash Flow Prior to Change in Accounting Principle Effect of Change Recast Prior to Change in Accounting Principle Effect of Change Recast Net income $ 40,797 $ 253 $ 41,050 $ 27,977 $ (619) $ 27,358 Deferred income taxes 1,240 158 1,398 4,014 (134) 3,880 Self-insurance accruals 9,202 (411) 8,791 16,091 753 16,844 Net cash provided by operating activities 83,353 — 83,353 62,104 — 62,104 Quarterly Results of Operations (Unaudited) Prior to Change in Accounting Principle Effect of Change Recast Fiscal 2020, Three Months Ended Mar 28 Gross profit (revenues less costs and expenses, operating) $ 89,887 $ (212) $ 89,675 Income from operations 3,934 (212) 3,722 Net income (loss) 173 (194) (21) Net income (loss) per share -- Basic 0.01 (0.01) — Net income (loss) per share -- Diluted 0.01 (0.01) — Fiscal 2020, Three Months Ended June 27 Gross profit (revenues less costs and expenses, operating) $ 128,187 $ 78 $ 128,265 Income from operations 44,311 78 44,389 Net income (loss) 29,785 96 29,881 Net income (loss) per share -- Basic 1.31 — 1.31 Net income (loss) per share -- Diluted 1.24 0.01 1.25 Quarterly Results of Operations (Unaudited) Prior to Change in Accounting Principle Effect of Change Recast Fiscal 2020, Three Months Ended Sept 26 Gross profit (revenues less costs and expenses, operating) $ 128,943 $ (128) $ 128,815 Income from operations 35,500 (128) 35,372 Net income (loss) 24,627 (92) 24,535 Net income (loss) per share -- Basic 1.08 (0.01) 1.07 Net income (loss) per share -- Diluted 1.03 — 1.03 Fiscal 2019, Three Months Ended Mar 30 Gross profit (revenues less costs and expenses, operating) $ 81,873 $ (153) $ 81,720 Income from operations 2,966 (153) 2,813 Net income (loss) (493) (100) (593) Net income (loss) per share -- Basic (0.02) (0.01) (0.03) Net income (loss) per share -- Diluted (0.02) (0.01) (0.03) Fiscal 2019, Three Months Ended June 29 Gross profit (revenues less costs and expenses, operating) $ 113,656 $ 6 $ 113,662 Income from operations 30,282 6 30,288 Net income (loss) 19,747 (18) 19,729 Net income (loss) per share -- Basic 0.86 — 0.86 Net income (loss) per share -- Diluted 0.82 — 0.82 Fiscal 2019, Three Months Ended Sept 28 Gross profit (revenues less costs and expenses, operating) $ 114,336 $ (56) $ 114,280 Income from operations 22,783 (56) 22,727 Net income (loss) 13,434 (37) 13,397 Net income (loss) per share -- Basic 0.59 — 0.59 Net income (loss) per share -- Diluted 0.56 — 0.56 Fiscal 2019, Three Months Ended Dec 31 Gross profit (revenues less costs and expenses, operating) $ 103,348 $ 614 $ 103,962 Income from operations 13,514 614 14,128 Net income (loss) 8,109 407 8,516 Net income (loss) per share -- Basic 0.35 0.02 0.37 Net income (loss) per share -- Diluted 0.34 0.01 0.35

Accounts Receivable, Net and _2

Accounts Receivable, Net and Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Dec. 31, 2020
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, Accounts receivable, net 2020 2019 Accounts receivable $ 214,887 $ 176,849 Unbilled receivables (1) 42,251 58,277 257,138 235,126 Less allowances for credit losses 4,217 3,815 Total $ 252,921 $ 231,311
Schedule of other current assets [Table Text Block]	The following items comprise the amounts included in the balance sheets. Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B: December 31, Other current assets 2020 2019 Refundable income taxes $ — $ 339 Other 778 984 Total $ 778 $ 1,323
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 20 years Leasehold improvements Shorter of lease term or estimated useful life; ranging from 5 to 20 years December 31, Property and equipment, net 2020 2019 Land and land improvements $ 19,731 $ 19,270 Buildings and leasehold improvements 49,460 44,414 Equipment 623,847 604,211 693,038 667,895 Less accumulated depreciation 488,321 468,045 Total $ 204,717 $ 199,850
Schedule of other assets, noncurrent [Table Text Block]	December 31, Other assets, noncurrent 2020 2019 Assets invested for self-insurance $ 19,359 $ 15,426 Investment--cost-method affiliate 1,258 1,314 Deferred income taxes 4,167 62 Other 4,972 5,595 Total $ 29,756 $ 22,397
Schedule of accrued expenses [Table Text Block]	December 31, Accrued expenses 2020 2019 Employee compensation $ 36,108 $ 26,381 Accrued compensated absences 14,534 10,744 Self-insured medical claims 2,065 1,824 Customer advances, deposits 2,067 1,674 Income taxes payable 6,926 6,420 Taxes, other than income 30,354 1,775 Other 6,387 3,613 Total $ 98,441 $ 52,431
Schedule of other liabilities, noncurrent [Table Text Block]	December 31, Other liabilities, noncurrent 2020 2019 Pension and retirement plans $ 7,365 $ 6,552 Other 3,324 5,149 Total $ 10,689 $ 11,701

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Supplemental cash flow information	Supplemental cash flow information follows: Year Ended December 31, Supplemental cash flow information 2020 2019 2018 Interest paid $ 7,159 $ 8,463 $ 6,375 Income taxes paid, net 27,494 5,758 11,514 Noncash transactions: Debt issued for purchases of businesses $ 2,472 $ 2,612 $ 2,402 Detail of acquisitions: Assets acquired: Cash $ — $ 3 $ — Accounts receivable 10 2,332 1,311 Operating supplies 22 84 23 Prepaid expense 6 27 89 Equipment 1,932 1,837 4,079 Other assets — 96 7 Intangible assets 3,545 4,067 4,895 Goodwill 5,635 4,174 2,840 Liabilities assumed (613) (1,479) (2,381) Debt issued for purchases of businesses (2,472) (2,612) (2,402) Cash paid $ 8,065 $ 8,529 $ 8,461

Identified Intangible Assets _2

Identified Intangible Assets and Goodwill, Net (Tables)	12 Months Ended
	Dec. 31, 2020
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 intangible assets and goodwill acquired in connection with our acquisitions were as follows: Weighted-Average December 31, 2020 December 31, 2019 Carrying Accumulated Carrying Accumulated Amortized intangible assets: Customer lists/relationships 3.5 years $ 30,402 $ 22,040 $ 28,301 $ 20,024 Employment-related 2.9 years 9,320 7,755 8,391 7,348 Tradenames 3.9 years 7,938 6,195 7,402 5,788 Amortized intangible assets 47,660 $ 35,990 44,094 $ 33,160 Less accumulated amortization 35,990 33,160 Intangible assets, net $ 11,670 $ 10,934 Goodwill $ 48,256 $ 42,285
Schedule of goodwill [Table Text Block]	The changes in the carrying amounts of goodwill, by segment, for the years ended December 31, 2020 and December 31, 2019 were as follow: Balance at Acquisitions Translation Balance at Utility $ 4,911 $ — $ — $ 4,911 Residential and Commercial 37,374 5,635 336 43,345 Total $ 42,285 $ 5,635 $ 336 $ 48,256 Balance at Acquisitions Translation Balance at Utility $ 4,911 $ — $ — $ 4,911 Residential and Commercial 33,060 4,174 140 37,374 Total $ 37,971 $ 4,174 $ 140 $ 42,285
Schedule of finite-lived intangible assets, future amortization expense [Table Text Block]	The aggregate amortization expense of intangible assets, as of December 31, 2020, in each of the next five years was as follows: Future Amortization Expense Year ending December 31, 2021 $ 2,733 2022 2,502 2023 2,333 2024 1,857 2025 1,284 Thereafter 961 $ 11,670

Short and Long-Term Debt and _2

Short and Long-Term Debt and Commitments Related to Letters of Credit (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of short-term debt [Table Text Block]	Short-term debt consisted of the following: December 31, 2020 2019 Notes payable $ — $ 1,853 Current portion of long-term debt 19,540 23,302 Current portion of finance leases 2,273 1,348 $ 21,813 $ 26,503
Schedule of long-term debt instruments [Table Text Block]	Long-term debt consisted of the following: December 31, 2020 2019 Revolving credit facility Swing-line borrowings $ — $ 10,000 LIBOR borrowings — 52,000 — 62,000 5.09% Senior unsecured notes — 6,000 3.99% Senior unsecured notes 50,000 50,000 4.00% Senior unsecured notes 25,000 25,000 Term loans 21,864 24,076 96,864 167,076 Less debt issuance costs 256 420 Less current portion 19,540 23,302 $ 77,068 $ 143,354

Self-Insurance Accruals (Tables

Self-Insurance Accruals (Tables)	12 Months Ended
	Dec. 31, 2020
Self-Insurance Accruals [Abstract]
Schedule of self-insurance accruals	Components of our self-insurance accruals for workers’ compensation, vehicle liability and general liability were as follows (Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B): December 31, 2020 2019 Workers' compensation $ 52,060 $ 44,383 Vehicle liability 10,046 12,209 General liability 47,174 39,091 Total 109,280 95,683 Less current portion 37,707 30,882 Noncurrent portion $ 71,573 $ 64,801
Schedule of changes in self-insurance accruals	The changes in our self-insurance accruals are summarized in the table below. December 31, 2020 2019 Balance, beginning of year $ 95,683 $ 86,884 Provision for claims 51,988 50,854 Payment of claims (38,391) (42,055) Balance, end of year $ 109,280 $ 95,683

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of assets and liabilities, leases	The following table summarizes the amounts recognized in our Consolidated Balance Sheet related to leases: Consolidated Balance Sheet Classification December 31, December 31, Assets Operating lease assets Right-of-use assets - operating leases $ 55,893 $ 40,033 Finance lease assets Property and equipment, net 8,788 3,183 Total lease assets $ 64,681 $ 43,216 Liabilities Current operating lease liabilities Current portion of operating lease liabilities $ 19,124 $ 14,665 Non-current operating lease liabilities Lease liabilities - operating leases 36,612 25,200 Total operating lease liabilities 55,736 39,865 Current portion of finance lease liabilities Current portion of long-term debt, finance lease liabilities and short-term debt 2,273 1,348 Non-current finance lease liabilities Lease liabilities - finance leases 6,479 1,795 Total finance lease liabilities 8,752 3,143 Total lease liabilities $ 64,488 $ 43,008
Lease, Cost [Table Text Block]	The components of lease cost recognized within our Consolidated Statement of Operations were as follows: Year Ended Consolidated Statement December 31, December 31, Operating lease cost Operating expense $ 11,349 $ 6,919 Operating lease cost Selling expense 9,572 8,699 Operating lease cost General and administrative expense 1,115 828 Finance lease cost: Amortization of right-of-use assets Depreciation 2,015 1,371 Interest expense on lease liabilities Interest expense 148 118 Other lease cost (1) Operating expense 5,357 4,211 Other lease cost (1) Selling expense 1,351 1,062 Other lease cost (1) General and administrative expense 52 16 Total lease cost $ 30,959 $ 23,224 (1) Other lease cost includes short-term lease costs and variable lease costs.
Schedule of remaining weighted average lease term [Table Text Block]	The table below summarizes the weighted average remaining lease term as of December 31, 2020. Operating leases 3.8 years Finance leases 5.4 years
Schedule of lease weighted average discount rate [Table Text Block]	The table below summarizes the weighted average discount rate used to measure our lease liabilities as of December 31, 2020. Operating leases 2.95 % Finance leases 1.88 %
Supplemental cash flow information, leases [Table Text Block]	Supplemental Cash Flow Information Related to Leases Year Ended December 31, December 31, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (21,786) $ (17,009) Operating cash flows from finance leases (148) (118) Financing cash flows from finance leases (1,996) (1,282) Right-of-use assets obtained in exchange for lease obligations: Operating leases 36,653 56,478 Finance leases 7,664 310
Finance and operating lease, liability, maturity [Table Text Block]	Maturity Analysis of Lease Liabilities As of December 31, 2020 Operating Finance Year ending December 31, 2021 $ 20,427 $ 2,414 2022 16,249 1,527 2023 9,778 1,327 2024 5,434 1,245 2025 2,616 1,151 Thereafter 4,107 1,529 Total lease payments 58,611 9,193 Less interest 2,875 441 Total $ 55,736 $ 8,752

Common Shares, Redeemable Com_2

Common Shares, Redeemable Common Shares and Preferred Shares (Tables)	12 Months Ended
	Dec. 31, 2020
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 Redeemable Total Shares outstanding, December 31, 2018 17,238,497 5,642,155 22,880,652 Shares purchased (853,738) (746,857) (1,600,595) Shares sold 471,898 251,584 723,482 Stock subscription offering, employee cash purchases 872,390 — 872,390 Options exercised 300,874 — 300,874 Shares outstanding, December 31, 2019 18,029,921 5,146,882 23,176,803 Shares purchased (1,076,028) (521,901) (1,597,929) Shares sold 523,144 487,903 1,011,047 Options exercised 230,231 — 230,231 Shares outstanding, December 31, 2020 17,707,268 5,112,884 22,820,152

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
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 Defined Accumulated Balance at January 1, 2018 $ (3,305) $ (5,088) $ (8,393) Unrealized gains (losses) (2,514) — (2,514) Amounts reclassified from accumulated other comprehensive income (loss) — 6,291 6,291 Tax effect — (145) (145) Unrecognized amounts from defined benefit pension plans — (279) (279) Tax effect — 6 6 Net of tax amount (2,514) 5,873 3,359 Balance at December 31, 2018 $ (5,819) $ 785 $ (5,034) Unrealized gains (losses) 1,186 — 1,186 Amounts reclassified from accumulated other comprehensive income (loss) — (1,551) (1,551) Tax effect — 143 143 Unrecognized amounts from defined benefit pension plans — (323) (323) Tax effect — 176 176 Net of tax amount 1,186 (1,555) (369) Balance at December 31, 2019 $ (4,633) $ (770) $ (5,403) Unrealized gains (losses) 895 — 895 Amounts reclassified from accumulated other comprehensive income (loss) — 152 152 Tax effect — (39) (39) Unrecognized amounts from defined benefit pension plans — (259) (259) Tax effect — 107 107 Net of tax amount 895 (39) 856 Balance at December 31, 2020 $ (3,738) $ (809) $ (4,547)

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [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 ("SSARs"), and restricted stock units ("RSUs")—included in the results of operations was as follows: Year Ended December 31, 2020 2019 2018 Compensation expense, all share-based payment plans $ 3,407 $ 2,845 $ 3,370 Income tax benefit 538 404 602
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, 2020: Stock-Settled Number of Weighted- Weighted- Unrecognized Aggregate Unvested, January 1, 2020 262,705 $ 3.47 Granted — — Forfeited (2,254) 3.53 Vested (155,215) 3.29 Unvested, December 31, 2020 105,236 $ 3.73 1.6 years $ 241 $ 2,620
Schedule of share-based compensation, restricted stock units award activity [Table Text Block]	The following table summarizes PRSUs and RSUs as of December 31, 2020: Restricted Stock Units Number of Weighted- Weighted- Unrecognized Aggregate Unvested, January 1, 2020 224,259 $ 17.11 Granted 98,863 23.74 Forfeited (1,871) 17.37 Vested (65,944) 15.52 Unvested, December 31, 2020 255,307 $ 20.09 2.4 years $ 2,778 $ 6,357 Employee PRSUs 220,157 $ 19.92 2.7 years $ 2,403 $ 5,482 Nonemployee Director RSUs 35,150 $ 21.14 1.4 years $ 375 $ 875
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, 2020 2019 2018 Volatility rate 9.7 % 9.9 % 10.1 % Risk-free interest rate .7 % 2.3 % 2.7 % Expected dividend yield .4 % .7 % .7 % Expected life of awards (years) 8.1 8.8 9.2
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, 2020: Stock Options Number of Weighted- Weighted- Unrecognized Aggregate Outstanding, January 1, 2020 1,428,082 $ 15.13 Granted 174,897 24.20 Exercised (166,675) 11.30 Forfeited (27,645) 16.79 Outstanding, December 31, 2020 1,408,659 $ 16.67 5.6 years $ 1,298 $ 11,593 Exercisable, December 31, 2020 940,277 $ 14.54 4.3 years $ 9,743
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, 2020 is summarized below: Stock Options Number Weighted-Average Weighted- Number Weighted- Employee options: $ 11.60 212,480 2.5 years $ 11.60 212,480 $ 11.60 13.20 240,084 3.5 years 13.20 240,084 13.20 15.05 191,265 4.5 years 15.05 191,265 15.05 16.35 210,165 5.5 years 16.35 159,165 16.35 17.60 121,550 6.5 years 17.60 73,650 17.60 19.10 127,950 7.5 years 19.10 42,000 19.10 21.10 26,500 8.2 years 21.10 4,260 21.10 21.10 112,068 8.5 years 21.10 17,373 21.10 24.20 28,397 9.5 years 24.20 — 24.20 24.20 138,200 9.2 years 24.20 — 24.20 1,408,659 5.6 years $ 16.67 940,277 $ 14.54

Defined Benefit Pension Plans (

Defined Benefit Pension Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [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, 2020 2019 Change in benefit obligation Projected benefit obligation at beginning of year $ 3,265 $ 7,064 Service cost — 45 Interest cost 105 170 Actuarial (gains)/losses 259 323 Settlements — (1,677) Benefits paid (158) (2,660) Projected benefit obligation at end of year $ 3,471 $ 3,265 Accumulated benefit obligation at end of year $ 3,471 $ 3,265
Schedule of changes in fair value of plan sssets [Table Text Block]	December 31, 2020 2019 Change in fair value of plan assets Fair value of plan assets at beginning of year $ — $ 3,758 Employer contributions 158 579 Settlements — (1,677) Benefits paid (158) (2,660) Fair value of plan assets at end of year $ — $ —
Schedule of net funded status [Table Text Block]	December 31, 2020 2019 Funded status of the plans Fair value of plan assets $ — $ — Projected benefit obligation 3,471 3,265 Funded status of the plans $ (3,471) $ (3,265) December 31, 2020 2019 Funded status by plan SERP $ (3,019) $ (2,833) Restoration Plan (452) (432) Funded status of the plans $ (3,471) $ (3,265)
Schedule of amounts recognized in balance sheet [Table Text Block]	December 31, 2020 2019 Amounts reported in the consolidated balance sheets Current liability $ (203) $ (202) Noncurrent liability (3,268) (3,063) Funded status of the plans $ (3,471) $ (3,265)
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, 2020 At December 31, 2019 Pretax Net of Tax Pretax Net of Tax Amounts reported in accumulated other comprehensive income Unrecognized net actuarial loss $ 892 $ 737 $ 723 $ 638 Unrecognized prior service cost 87 72 150 132 Amounts reported in accumulated other comprehensive income $ 979 $ 809 $ 873 $ 770
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 2021 follows: Year ending December 31, 2021 Pretax Net of Tax Amortization of Costs Expected to be Recognized Next Year Unrecognized net actuarial loss $ 138 $ 100 Unrecognized prior service cost 63 46 Amortization of Costs Expected to be Recognized Next Year $ 201 $ 146
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, 2020 2019 For pension plans with accumulated benefit obligations in excess of plan assets Projected benefit obligation $ 3,471 $ 3,265 Accumulated benefit obligation 3,471 3,265 Fair value of plan assets — —
Schedule of assumptions used [Table Text Block]	The discount rates used to measure the year-end benefit obligation and compute pension expense for the subsequent year were: December 31, 2020 2019 2018 Actuarial assumptions - Discount Rate SERP 3.34 % 3.34 % 4.37 % Restoration Plan 3.23 % 3.23 % 4.28 %
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, 2020 2019 2018 Components of pension expense (income) Service costs--increase in benefit obligation earned $ — $ 75 $ 400 Interest cost on projected benefit obligation 105 198 718 Expected return on plan assets — (59) (231) Settlement loss — 1,677 5,499 Amortization of net actuarial loss 89 87 728 Amortization of prior service cost 64 64 64 Net pension expense of defined benefit pension plans $ 258 $ 2,042 $ 7,178
Schedule of expected benefit payments [Table Text Block]	The benefits, as of December 31, 2020, 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, follows: Participants Benefits Estimated future payments Year ending December 31, 2021 $ 205 2022 202 2023 198 2024 194 2025 189 Years 2026 to 2030 988
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. Pension Fund EIN/Pension Pension FIP/RP Davey Tree Surcharge Expiration 2020 2019 2020 2019 2018 National Electric 53-0181657/001 Green Green No $ 3,239 $ 904 $ 768 No Ranging from December 31, 2020 to Eighth District 84-6100393/001 Green Green No 161 190 142 No December 31, 2023 $ 3,400 $ 1,094 $ 910

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of income before income tax, domestic and foreign [Table Text Block]	Income (loss) before income taxes was attributable to the following sources: Year Ended December 31, 2020 2019 2018 United States $ 82,382 $ 54,569 $ 36,624 Canada 1,500 (891) 119 Total $ 83,882 $ 53,678 $ 36,743
Schedule of components of income tax expense (benefit) [Table Text Block]	The provision for income taxes follows: Year Ended December 31, 2020 2019 2018 Current provision (benefit): Federal $ 22,093 $ 7,934 $ 3,165 State 6,260 3,624 2,290 Canadian (50) (328) 50 Total current 28,303 11,230 5,505 Deferred taxes (5,358) 1,398 3,880 Total taxes on income $ 22,945 $ 12,628 $ 9,385
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, 2020 2019 2018 Statutory U.S. federal tax rate 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit 5.2 5.6 5.7 Effect of Canadian income taxes .2 — .1 Nondeductible expenses 1.3 2.2 2.1 Stock compensation (.3) (1.8) (.7) ESOP dividend deduction (.1) (.2) (.3) Uncertain tax adjustments and audit settlement .1 .2 (3.8) Pension termination — (2.9) — All other, net — (.7) 1.4 Effective income tax rate 27.4 % 23.4 % 25.5 %
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, 2020 2019 Deferred tax assets: Self-insurance accruals $ 22,847 $ 20,120 Accrued compensated absences 1,876 1,389 Accrued expenses and other liabilities 942 841 Accrued stock compensation 2,105 1,906 Foreign tax credit carryforward 1,597 2,137 Other future deductible amounts, net 4,076 4,167 33,443 30,560 Less deferred tax asset valuation allowance 1,185 1,683 32,258 28,877 Deferred tax liabilities: Intangibles 1,407 1,065 Prepaid expenses 4,243 3,701 Property and equipment 22,441 24,049 28,091 28,815 Net deferred tax asset--noncurrent $ 4,167 $ 62
Summary of unrecognized income tax benefits [Table Text Block]	The balance of unrecognized benefits and the amount of related interest and penalties at December 31, were as follows: December 31, 2020 2019 Unrecognized tax benefits $ 1,183 $ 1,850 Portion, if recognized, would reduce tax expense and effective tax rate 735 654 Accrued interest on unrecognized tax benefits 72 64
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, 2020 2019 2018 Balance, beginning of year $ 1,850 $ 1,325 $ 2,581 Additions based on tax positions related to the current year — 547 224 Reductions based on tax positions related to the current year (187) — — Additions for tax positions of prior years 101 23 20 Reductions for tax positions of prior years — — (1,500) Lapses in statutes of limitations (581) (45) — Balance, end of year $ 1,183 $ 1,850 $ 1,325

Earnings Per Share Information

Earnings Per Share Information (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of earnings per share calculation [Table Text Block]	Earnings per share is computed as follows: Year Ended December 31, 2020 2019 2018 Income available to common shareholders: Net income $ 60,937 $ 41,050 $ 27,358 Weighted-average shares: Basic: Outstanding 21,981,950 22,906,264 23,698,478 Partially-paid share subscriptions — — 690,260 Basic weighted-average shares 21,981,950 22,906,264 24,388,738 Diluted: Basic from above 21,981,950 22,906,264 24,388,738 Incremental shares from assumed: Exercise of stock subscription purchase rights — 54,961 141,287 Exercise of stock options and awards 1,051,136 1,016,864 950,593 Diluted weighted-average shares 23,033,086 23,978,089 25,480,618 Share data: Earnings per share--basic $ 2.77 $ 1.79 $ 1.12 Earnings per share--diluted $ 2.65 $ 1.71 $ 1.07 Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B

Operations by Business Segmen_2

Operations by Business Segment and Geographic Information Operations by business segment (Tables)	12 Months Ended
	Dec. 31, 2020
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 Residential All Reconciling Consolidated Fiscal Year 2020 Revenues $ 739,118 $ 545,357 $ 3,077 $ — $ 1,287,552 Income (loss) from operations 73,592 53,623 (25,297) (7,717) (a) 94,201 Interest expense (6,899) (6,899) Interest income 2,135 2,135 Other income (expense), net (5,555) (5,555) Income before income taxes $ 83,882 Depreciation $ 27,545 $ 23,553 $ — $ 2,790 (b) $ 53,888 Amortization 530 2,297 — — 2,827 Capital expenditures 22,595 21,327 — 7,728 51,650 Segment assets, total 280,467 238,876 — 136,011 (c) 655,354 Fiscal Year 2019 Revenues $ 607,556 $ 534,655 $ 1,509 $ — $ 1,143,720 Income (loss) from operations 37,696 52,471 (12,963) (7,248) (a) 69,956 Interest expense (8,514) (8,514) Interest income 348 348 Other income (expense), net (8,112) (8,112) Income before income taxes $ 53,678 Depreciation $ 30,304 $ 23,537 $ — $ 3,451 (b) $ 57,292 Amortization 474 2,071 — — 2,545 Capital expenditures 26,528 24,573 — 7,564 58,665 Segment assets, total 267,982 226,313 — 102,629 (c) 596,924 Fiscal Year 2018 Revenues $ 537,484 $ 486,005 $ 1,302 $ — $ 1,024,791 Income (loss) from operations 32,370 47,812 (20,569) (4,676) (a) 54,937 Interest expense (7,039) (7,039) Interest income 350 350 Other income (expense), net (11,505) (11,505) Income before income taxes $ 36,743 Depreciation $ 29,526 $ 21,720 $ — $ 3,668 (b) $ 54,914 Amortization 211 1,842 — 2 2,055 Capital expenditures 32,148 22,256 — 6,006 60,410 Segment assets, total 239,426 208,369 — 78,828 (c) 526,623 Certain amounts in prior years have been recast as a result of the change in accounting principle as discussed in Note B Reconciling adjustments from segment reporting to consolidated external financial reporting include unallocated corporate items: (a) 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.
Schedule of revenue from external customers and long-lived assets 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, 2020 2019 2018 Revenues United States $ 1,214,628 $ 1,066,035 $ 949,317 Canada 72,924 77,685 75,474 $ 1,287,552 $ 1,143,720 $ 1,024,791 December 31, 2020 2019 2018 Long-lived assets, net United States $ 324,776 $ 288,196 $ 251,181 Canada 25,516 27,303 20,374 $ 350,292 $ 315,499 $ 271,555

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue Recognition [Abstract]
Disaggregation of revenue [Table Text Block]	The following tables disaggregate our revenue for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 by major sources: Year Ended December 31, 2020 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 535,260 $ 318,061 $ 61 $ 853,382 Grounds maintenance — 138,885 — 138,885 Storm damage services 20,907 9,724 — 30,631 Consulting and other 182,951 78,687 3,016 264,654 Total revenues $ 739,118 $ 545,357 $ 3,077 $ 1,287,552 Geography: United States $ 703,324 $ 508,227 $ 3,077 $ 1,214,628 Canada 35,794 37,130 — 72,924 Total revenues $ 739,118 $ 545,357 $ 3,077 $ 1,287,552 Year Ended December 31, 2019 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 448,325 $ 305,365 $ (108) $ 753,582 Grounds maintenance — 152,283 — 152,283 Storm damage services 3,096 4,905 — 8,001 Consulting and other 156,135 72,102 1,617 229,854 Total revenues $ 607,556 $ 534,655 $ 1,509 $ 1,143,720 Geography: United States $ 567,134 $ 497,392 $ 1,509 $ 1,066,035 Canada 40,422 37,263 — 77,685 Total revenues $ 607,556 $ 534,655 $ 1,509 $ 1,143,720 Year Ended December 31, 2018 Utility Residential and Commercial All Other Consolidated Type of service: Tree and plant care $ 394,481 $ 290,940 $ (1,520) $ 683,901 Grounds maintenance — 117,498 — 117,498 Storm damage services 13,864 9,447 — 23,311 Consulting and other 129,139 68,120 2,822 200,081 Total revenues $ 537,484 $ 486,005 $ 1,302 $ 1,024,791 Geography: United States $ 499,242 $ 448,773 $ 1,302 $ 949,317 Canada 38,242 37,232 — 75,474 Total revenues $ 537,484 $ 486,005 $ 1,302 $ 1,024,791
Contract with customer, asset and liability [Table Text Block]	Net contract liabilities consisted of the following: December 31, December 31, Contract liabilities - current $ 3,242 $ 3,129 Contract liabilities - noncurrent 1,754 2,705 Net contract liabilities $ 4,996 $ 5,834

Fair Value Measurements and F_2

Fair Value Measurements and Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and December 31, 2019, were as follows: Fair Value Measurements at December 31, 2020 Using: Total Quoted Significant Significant Description December 31, 2020 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 19,359 $ 19,359 $ — $ — Liabilities: Deferred compensation $ 3,192 $ — $ 3,192 $ — Fair Value Measurements at December 31, 2019 Using: Total Quoted Significant Significant Description December 31, 2019 (Level 1) (Level 2) (Level 3) Assets: Assets invested for self-insurance, classified as other assets, noncurrent $ 15,402 $ 15,402 $ — $ — Liabilities: Deferred compensation $ 2,786 $ — $ 2,786 $ —
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, 2020 December 31, 2019 Carrying Fair Carrying Fair Revolving credit facility, noncurrent $ — $ — $ 62,000 $ 62,000 Senior unsecured notes 75,000 81,424 75,000 79,558 Term loans, noncurrent 2,324 2,451 6,774 7,124 Total $ 77,324 $ 83,875 $ 143,774 $ 148,682

Quarterly Results of Operatio_2

Quarterly Results of Operations Quarterly Results of Operations (Tables)	12 Months Ended
	Dec. 31, 2020
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 2020 and 2019. Fiscal 2020, Three Months Ended Mar 28 June 27 Sept 26 Dec 31 Revenues $ 288,280 $ 319,247 $ 337,453 $ 342,572 Gross profit (revenues less costs and expenses, operating) 89,675 128,265 128,815 117,500 Income from operations 3,722 44,389 35,372 10,718 Net income (loss) (21) 29,881 24,535 6,542 Net income (loss) per share -- Basic $ — $ 1.31 $ 1.07 $ .39 Net income (loss) per share -- Diluted $ — $ 1.25 $ 1.03 $ .37 ESOT valuation per share $ 24.20 $ 24.90 $ 24.90 $ 30.00 Fiscal 2019, Three Months Ended Mar 30 June 29 Sept 28 Dec 31 Revenues $ 247,889 $ 301,434 $ 307,473 $ 286,924 Gross profit (revenues less costs and expenses, operating) 81,720 113,662 114,280 103,962 Income from operations 2,813 30,288 22,727 14,128 Net income (loss) (593) 19,729 13,397 8,516 Net income (loss) per share -- Basic $ (.03) $ .86 $ .59 $ .37 Net income (loss) per share -- Diluted $ (.03) $ .82 $ .56 $ .35 ESOT valuation per share $ 21.10 $ 22.60 $ 22.60 $ 24.20 Certain amounts in prior quarters and prior years have been recast as a result of the change in accounting principle as discussed in Note B Fourth quarters of 2020 and 2019 include adjustments to casualty insurance expense that had the effect of increasing gross profit in 2020 by $915 and decreasing gross profit in 2019 by $2,077.

Our Business Reportable segment

Our Business Reportable segments (Details)	12 Months Ended
	Dec. 31, 2020
Segment reporting, disclosure of entity's reportable segments
Number of reportable segments	2

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2020
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)	7 years
Land improvements | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	5 years
Land improvements | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	20 years
Buildings | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	5 years
Buildings | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	30 years
Equipment | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	3 years
Equipment | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	20 years
Leasehold improvements | Minimum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	5 years
Leasehold improvements | Maximum [Member]
Property, plant and equipment [Line Items]
Property and equipment, estimated useful lives (in years)	20 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Goodwill impairment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Goodwill, impairment loss	$ 0	$ 0	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Concentration of Risk (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Customer concentration risk [Member]
Concentration risk, percentage	17.00%	12.00%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in Accounting Estimate [Line Items]
Self-insurance accruals	$ 71,573				$ 64,801				$ 71,573	$ 64,801
Other assets (noncurrent)	29,756				22,397				29,756	22,397
Other liabilities, noncurrent, total	10,689				11,701				10,689	11,701
Retained earnings	206,711				177,711				206,711	177,711
Operating expense									823,297	730,096	$ 666,141
Gross profit (revenues less costs and expenses, operating)	117,500	$ 128,815	$ 128,265	$ 89,675	103,962	$ 114,280	$ 113,662	$ 81,720
Income from operations	10,718	35,372	44,389	3,722	14,128	22,727	30,288	2,813	94,201	69,956	54,937
Income before income taxes									83,882	53,678	36,743
Income tax expense									22,945	12,628	9,385
Net income (loss)	$ 6,542	$ 24,535	$ 29,881	$ (21)	$ 8,516	$ 13,397	$ 19,729	$ (593)	$ 60,937	$ 41,050	$ 27,358
Earnings per share--basic	$ 0.39	$ 1.07	$ 1.31	$ 0	$ 0.37	$ 0.59	$ 0.86	$ (0.03)	$ 2.77	$ 1.79	$ 1.12
Earnings per share--diluted	$ 0.37	$ 1.03	$ 1.25	$ 0	$ 0.35	$ 0.56	$ 0.82	$ (0.03)	$ 2.65	$ 1.71	$ 1.07
Deferred income taxes									$ (5,358)	$ 1,398	$ 3,880
Self-insurance accruals									13,597	8,791	16,844
Net cash provided by operating activities									$ 152,081	83,353	62,104
Prior to Change in Accounting Principle
Change in Accounting Estimate [Line Items]
Self-insurance accruals					$ 62,113					62,113
Other assets (noncurrent)					22,335					22,335
Other liabilities, noncurrent, total					12,268					12,268
Retained earnings					179,770					179,770
Operating expense										730,507	665,388
Gross profit (revenues less costs and expenses, operating)		$ 128,943	$ 128,187	$ 89,887	103,348	$ 114,336	$ 113,656	$ 81,873
Income from operations		35,500	44,311	3,934	13,514	22,783	30,282	2,966		69,545	55,690
Income before income taxes										53,267	37,496
Income tax expense										12,470	9,519
Net income (loss)		$ 24,627	$ 29,785	$ 173	$ 8,109	$ 13,434	$ 19,747	$ (493)		$ 40,797	$ 27,977
Earnings per share--basic		$ 1.08	$ 1.31	$ 0.01	$ 0.35	$ 0.59	$ 0.86	$ (0.02)		$ 1.78	$ 1.15
Earnings per share--diluted			$ 1.24	$ 0.01	$ 0.34	$ 0.56	$ 0.82	$ (0.02)		$ 1.70	$ 1.10
Deferred income taxes										$ 1,240	$ 4,014
Self-insurance accruals										9,202	16,091
Net cash provided by operating activities										83,353	62,104
Effect of Change
Change in Accounting Estimate [Line Items]
Self-insurance accruals					$ 2,688					2,688
Other assets (noncurrent)					62					62
Other liabilities, noncurrent, total					(567)					(567)
Retained earnings					(2,059)					(2,059)	(2,312)	$ (1,693)
Operating expense										(411)	753
Gross profit (revenues less costs and expenses, operating)		$ (128)	$ 78	$ (212)	614	$ (56)	$ 6	$ (153)
Income from operations		(128)	78	(212)	614	(56)	6	(153)		411	(753)
Income before income taxes										411	(753)
Income tax expense										158	(134)
Net income (loss)		$ (92)	$ 96	$ (194)	$ 407	$ (37)	$ (18)	$ (100)		$ 253	$ (619)
Earnings per share--basic		$ (0.01)	$ 0	$ (0.01)	$ 0.02	$ 0	$ 0	$ (0.01)		$ 0.01	$ (0.03)
Earnings per share--diluted		$ 0	$ 0.01	$ (0.01)	$ 0.01	$ 0	$ 0	$ (0.01)		$ 0.01	$ (0.03)
Deferred income taxes										$ 158	$ (134)
Self-insurance accruals										(411)	753
Net cash provided by operating activities										$ 0	$ 0

Recent Accounting Guidance Rece

Recent Accounting Guidance Recent accounting guidance (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Operating lease assets	$ 55,893	$ 40,033
Non-current operating lease liabilities	$ 36,612	$ 25,200
Other Noncurrent Assets [Member] | Accounting Standards Update 2016-02 [Member]
Operating lease assets			$ 37,429
Other Noncurrent Liabilities [Member] | Accounting Standards Update 2016-02 [Member]
Non-current operating lease liabilities			$ 37,429

Business Combinations (Details)

Business Combinations (Details)	2 Months Ended	12 Months Ended
	Mar. 08, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business acquisition [Line Items]
Investments in businesses		$ 11,150,000	$ 12,620,000	$ 13,244,000
Liabilities assumed		613,000	1,479,000	2,381,000
Debt issued		2,472,000	2,612,000	2,402,000
Goodwill		5,635,000	4,174,000	2,840,000
Goodwill acquired during period, tax deductible amount		$ 5,635,000	$ 1,610,000	$ 2,840,000
Subsequent event [Member]
Business acquisition [Line Items]
Investments in businesses	$ 10,522,000
Liabilities assumed	53,000
Debt issued	$ 2,263,000
Number of Businesses Acquired	3
Tradenames
Business acquisition [Line Items]
Intangible assets, estimated useful life (in years)		6 years
Noncompete agreements [Member]
Business acquisition [Line Items]
Intangible assets, estimated useful life (in years)		5 years

Accounts Receivable, Net and _3

Accounts Receivable, Net and Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, net
Accounts receivable	$ 214,887	$ 176,849
Unbilled receivables (1)	42,251	58,277
Accounts receivable, gross, current	257,138	235,126
Less allowances for credit losses	4,217	3,815
Accounts receivable, net	252,921	231,311
Other current assets
Refundable income taxes	0	339
Other	778	984
Other current assets, total	778	1,323
Property, plant and equipment
Land and land improvements	19,731	19,270
Buildings and leasehold improvements	49,460	44,414
Equipment	623,847	604,211
Property and equipment	693,038	667,895
Less accumulated depreciation	488,321	468,045
Property and equipment, net	204,717	199,850
Other assets, noncurrent
Assets invested for self-insurance	19,359	15,426
Investment--cost-method affiliate	1,258	1,314
Other	4,972	5,595
Other assets, noncurrent, total	29,756	22,397
Accrued expenses
Employee compensation	36,108	26,381
Accrued compensated absences	14,534	10,744
Self-insured medical claims	2,065	1,824
Customer advances, deposits	2,067	1,674
Income taxes payable	6,926	6,420
Taxes, other than income	30,354	1,775
Other	6,387	3,613
Accrued expenses, total	98,441	52,431
Other liabilities, noncurrent
Pension and retirement plans	7,365	6,552
Other	3,324	5,149
Other liabilities, noncurrent, total	10,689	11,701
Net deferred tax asset--noncurrent	$ 4,167	$ 62

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Interest paid	$ 7,159	$ 8,463	$ 6,375
Supplemental cash flow information
Income taxes paid, net	27,494	5,758	11,514
Noncash transactions:
Debt issued for purchases of businesses	(2,472)	(2,612)	(2,402)
Detail of acquisitions:
Cash	0	3	0
Accounts receivable	10	2,332	1,311
Operating supplies	22	84	23
Prepaid expense	6	27	89
Equipment	1,932	1,837	4,079
Other assets	0	96	7
Intangible assets	3,545	4,067	4,895
Goodwill	5,635	4,174	2,840
Liabilities assumed	613	1,479	2,381
Cash paid	$ 8,065	$ 8,529	$ 8,461

Identified Intangible Assets _3

Identified Intangible Assets and Goodwill, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, gross	$ 47,660	$ 44,094
Accumulated amortization	35,990	33,160
Intangible assets, net	11,670	10,934
Goodwill	$ 48,256	42,285	$ 37,971
Customer Lists [Member]
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, remaining amortization period	3 years 6 months
Finite-lived intangible assets, gross	$ 30,402	28,301
Accumulated amortization	$ 22,040	20,024
Employment-related
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	$ 9,320	8,391
Accumulated amortization	$ 7,755	7,348
Tradenames
Acquired finite-lived intangible assets [line Items]
Finite-lived intangible assets, remaining amortization period	3 years 10 months 24 days
Finite-lived intangible assets, gross	$ 7,938	7,402
Accumulated amortization	$ 6,195	$ 5,788

Identified Intangible Assets _4

Identified Intangible Assets and Goodwill, Net Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill, balance at January 1	$ 42,285	$ 37,971
Goodwill, acquisitions	5,635	4,174	$ 2,840
Goodwill, translation and other adjustments	336	140
Goodwill, balance at December 31	48,256	42,285	37,971
Utility
Goodwill [Roll Forward]
Goodwill, balance at January 1	4,911	4,911
Goodwill, acquisitions	0	0
Goodwill, translation and other adjustments	0	0
Goodwill, balance at December 31	4,911	4,911	4,911
Residential and Commercial
Goodwill [Roll Forward]
Goodwill, balance at January 1	37,374	33,060
Goodwill, acquisitions	5,635	4,174
Goodwill, translation and other adjustments	336	140
Goodwill, balance at December 31	$ 43,345	$ 37,374	$ 33,060

Identified Intangible Assets _5

Identified Intangible Assets and Goodwill, Net (Future Amortization of Intangibles) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-lived intangible assets, net, amortization expense, fiscal year maturity [Abstract]
Year ending December 31, 2021	$ 2,733
2022	2,502
2023	2,333
2024	1,857
2025	1,284
Thereafter	961
Intangible assets, net	$ 11,670	$ 10,934

Short and Long-Term Debt and _3

Short and Long-Term Debt and Commitments Related to Letters of Credit Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt instrument [Line Items]
Notes payable	$ 0	$ 1,853
Current portion of finance leases	2,273	1,348
Short-term debt	21,813	26,503
Revolving credit facility, noncurrent	0	62,000
Term loans	21,864	24,076
Long-term debt	96,864	167,076
Less debt issuance costs	256	420
Less current portion	19,540	23,302
Long-term debt, excluding current maturities	$ 77,068	143,354
Minimum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.10%
Maximum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.225%
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	0	52,000
5.09% Senior unsecured notes [Member]
Debt instrument [Line Items]
Senior unsecured notes	$ 0	6,000
Accounts receivable securitization [Member] | Base rate, federal funds [Member]
Debt instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
3.99% Senior unsecured notes [Member]
Debt instrument [Line Items]
Senior unsecured notes	$ 50,000	50,000
Unsecured debt additional shelf note capacity allowed by credit facility	25,000
Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	88,242	81,619
Letter of credit [Member] | Accounts receivable securitization [Member]
Debt instrument [Line Items]
Letters of credit outstanding	$ 83,355	$ 76,732
Letter of credit [Member] | Accounts receivable securitization [Member] | Minimum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
Letter of credit [Member] | Accounts receivable securitization [Member] | Maximum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.45%
Line of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, noncurrent	$ 2,877
Line of credit [Member] | LIBOR borrowings [Member]
Debt instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Line of credit [Member] | Base rate, federal funds [Member]
Debt instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Line of credit [Member] | Minimum [Member] | LIBOR borrowings [Member]
Debt instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.875%
Line of credit [Member] | Maximum [Member] | LIBOR borrowings [Member]
Debt instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%

Short and Long-Term Debt and _4

Short and Long-Term Debt and Commitments Related to Letters of Credit Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Debt instrument [Line Items]
Committed under credit facility	$ 9,168
Revolving credit facility, current borrowing capacity	250,000
Revolving credit facility, maximum borrowing capacity	$ 325,000
Number of principal payments	5
Anniversary when principal payments begin	6
Debt Instrument, Annual Principal Payment	$ 10,000
Unused commitments under credit facility	247,123
Revolving credit facility, noncurrent	$ 0	$ 62,000
Long-term debt, weighted average interest rate	3.89%	4.02%
Long-term debt, fiscal year maturity [Abstract]
2021	$ 19,539
2022	1,673
2023	652
2024	15,000
2025	15,000
thereafter	$ 45,000
Minimum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.10%
Maximum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.225%
Line of credit [Member]
Debt instrument [Line Items]
Revolving credit facility, noncurrent	$ 2,877
Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	$ 88,242	$ 81,619
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%
Base rate, federal funds [Member] | Line of credit [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	0.50%
Swing-line borrowings [Member]
Debt instrument [Line Items]
Revolving credit facility, current borrowing capacity	$ 25,000
Revolving credit facility, noncurrent	0	10,000
Line of credit [Member] | Letter of credit [Member]
Debt instrument [Line Items]
Letters of credit outstanding	2,010	2,010
5.09% Senior unsecured notes [Member]
Debt instrument [Line Items]
Senior unsecured notes	$ 0	6,000
Senior unsecured notes, interest rate	5.09%
Debt Instrument, Face Amount	$ 30,000
3.99% Senior unsecured notes [Member]
Debt instrument [Line Items]
Senior unsecured notes	$ 50,000	50,000
Senior unsecured notes, interest rate	3.99%
Debt Instrument, Face Amount	$ 50,000
Unsecured debt additional shelf note capacity	50,000
Unsecured debt maximum borrowing capacity allowed by credit facility	75,000
Unsecured debt additional shelf note capacity allowed by credit facility	25,000
4.00% Senior unsecured notes [Member]
Debt instrument [Line Items]
Senior unsecured notes	$ 25,000	25,000
Senior unsecured notes, interest rate	4.00%
Unsecured debt additional shelf note capacity	$ 25,000
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	$ 2,877	2,877
Accounts receivable securitization [Member]
Debt instrument [Line Items]
Senior unsecured notes, interest rate	1.00%
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
Letters of credit outstanding	$ 83,355	$ 76,732
Debt instrument, term (in years)	1 year
Accounts receivable securitization [Member] | Letter of credit [Member] | Minimum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
Accounts receivable securitization [Member] | Letter of credit [Member] | Maximum [Member]
Debt instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.45%
Accounts receivable securitization [Member] | Base rate, federal funds [Member]
Debt instrument [Line Items]
Outstanding borrowings interest rate margin adjustment range	0.50%
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

Self-Insurance Accruals (Detail

Self-Insurance Accruals (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Self-Insurance Accruals [Abstract]
Workers' compensation			$ 52,060	$ 44,383
Vehicle liability			10,046	12,209
General liability			47,174	39,091
Total	$ 95,683	$ 95,683	109,280	95,683
Less current portion			37,707	30,882
Noncurrent portion			$ 71,573	$ 64,801
Loss contingency accrual
Balance, beginning of year	95,683	86,884
Provision for claims	51,988	50,854
Payment of claims	(38,391)	(42,055)
Balance, end of year	$ 109,280	$ 95,683

Leases Assets and liabilities l

Leases Assets and liabilities leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of lease assets and liabilities [Line Items]
Operating lease assets	$ 55,893	$ 40,033
Finance lease assets	8,788	3,183
Total lease assets	64,681	43,216
Current operating lease liabilities	19,124	14,665
Non-current operating lease liabilities	36,612	25,200
Total operating lease liabilities	55,736	39,865
Current portion of finance lease liabilities	2,273	1,348
Non-current finance lease liabilities	6,479	1,795
Total finance lease liabilities	8,752	3,143
Total lease liabilities	$ 64,488	$ 43,008

Leases Lease cost (Details)

Leases Lease cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income and expenses, lessee [Line Items]
Finance leases, amortization of right-of-use asset	$ 2,015	$ 1,371
Interest expense on lease liabilities	148	118
Total lease cost	30,959	23,224
Operating expense [Member]
Income and expenses, lessee [Line Items]
Operating lease cost	11,349	6,919
Other lease cost	5,357	4,211
Selling expense [Member]
Income and expenses, lessee [Line Items]
Operating lease cost	9,572	8,699
Other lease cost	1,351	1,062
General and administrative expense [Member]
Income and expenses, lessee [Line Items]
Operating lease cost	1,115	828
Other lease cost	$ 52	$ 16

Leases Weighted average remaini

Leases Weighted average remaining lease term (Details)	Dec. 31, 2020
Leases [Abstract]
Operating lease, weighted average remaining lease term	3 years 9 months 18 days
Finance lease, weighted average remaining lease term	5 years 4 months 24 days

Leases Weighted average interes

Leases Weighted average interest rate (Details)	Dec. 31, 2020
Leases [Abstract]
Operating lease, weighted average discount rate, percent	2.95%
Finance lease, weighted average discount rate, percent	1.88%

Leases Supplemental cash flow i

Leases Supplemental cash flow information for leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating cash flows from operating leases	$ 21,786	$ 17,009
Operating cash flows from finance leases	148	118
Lessee, Finance Lease, Variable Lease Payment, Terms and Conditions	1,996	1,282
Right-of-use asset obtained in exchange for operating lease liability	36,653	56,478
Right-of-use asset obtained in exchange for finance lease liability	$ 7,664	$ 310

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Year ending December 31, 2021	$ 20,427
2022	16,249
2023	9,778
2024	5,434
2025	2,616
Thereafter	4,107
Total lease payments	58,611
Less interest	2,875
Total	55,736	$ 39,865
Year ending December 31, 2021	2,414
2022	1,527
2023	1,327
2024	1,245
2025	1,151
Thereafter	1,529
Total lease payments	9,193
Less interest	441
Total	$ 8,752	$ 3,143

Common Shares, Redeemable Com_3

Common Shares, Redeemable Common Shares and Preferred Shares Common shares outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Preferred shares
Preferred stock, shares authorized	4,000,000
Preferred stock, par value	$ 0
Preferred stock, shares issued	0
Redeemable stock, outstanding	5,112,884	5,146,882	5,642,155
Common stock, number of shares, par value and other disclosures [Abstract]
Common stock, shares authorized	48,000,000
Common stock, par value (in dollars per share)	$ 1
Common stock, shares issued	37,800,876	37,766,878	37,271,606
Treasury stock, shares	20,093,608	19,736,957	20,033,108
Shares purchased, value	$ 39,079	$ 34,647	$ 51,116
Common shares, direct sales	17,315
Common shares, value, direct sales	$ 430
Stock issued during period, shares, employee benefit plan	179,445
Stock issued during period, value, employee retirement plan	$ 4,376
Common shares, employer matching contribution, shares	420,719
Employee retirement plan, employer match	$ 10,282
Accrued 401K match	$ 1,800
Stock issued during period, shares, employee stock purchase plan	393,568
Increase (decrease) in stockholders' equity [Roll Forward]
Shares outstanding, beginning of year	23,176,803	22,880,652
Shares purchased	(1,597,929)	(1,600,595)
Shares sold	1,011,047	723,482
Stock subscription offering, employee cash purchases		872,390
Options exercised	230,231	300,874
Shares outstanding, end of year	22,820,152	23,176,803	22,880,652
Per share amounts and common shares outstanding [Abstract]
Share-based compensation arrangement by share-based payment award, options, exercisable, number	940,277
Treasury stock [Member]
Common stock, number of shares, par value and other disclosures [Abstract]
Shares purchased, value	$ 39,079	$ 34,647	$ 51,116
Employee stock option [Member]
Per share amounts and common shares outstanding [Abstract]
Share-based compensation arrangement by share-based payment award, options, exercisable, number	940,277

Common Shares, Redeemable Com_4

Common Shares, Redeemable Common Shares and Preferred Shares Stock subscription (Details)	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Stock subscription offering [Abstract]
Stock subscription offering, subscription price | $ / shares	$ 9.85
Stock subscription offering, number of shares subscribed | shares	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 | shares	3
Stock subscription offering, number of rights issued | shares	423,600
Stock subscription offering, right expiration term	seven

Common Shares, Redeemable Com_5

Common Shares, Redeemable Common Shares and Preferred Shares Common shares by class (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Shares, Outstanding	22,820,152	23,176,803	22,880,652
Treasury Stock, Shares, Acquired	(1,597,929)	(1,600,595)
Shares sold	1,011,047	723,482
Stock subscription offering, employee cash purchases		872,390
Options exercised	230,231	300,874
Permanent equity [Member]
Class of Stock [Line Items]
Shares, Outstanding	17,707,268	18,029,921	17,238,497
Treasury Stock, Shares, Acquired	(1,076,028)	(853,738)
Shares sold	523,144	471,898
Stock subscription offering, employee cash purchases		872,390
Options exercised	230,231	300,874
Temporary equity [Member]
Class of Stock [Line Items]
Shares, Outstanding	5,112,884	5,146,882
Treasury Stock, Shares, Acquired	(521,901)	(746,857)
Shares sold	487,903	251,584
Stock subscription offering, employee cash purchases		0
Options exercised	0	0

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	$ (4,547,000)	$ (5,403,000)	$ (5,034,000)	$ (8,393,000)
Unrealized gains (losses)	895,000	1,186,000	(2,514,000)
Amounts reclassified from accumulated other comprehensive income (loss)	152,000	(1,551,000)	6,291,000
Tax effect	(39,000)	143,000	(145,000)
Unrecognized amounts from defined benefit pension plans	(259,000)	(323,000)	(279,000)
Tax effect	107,000	176,000	6,000
Net of tax amount	856,000	(369,000)	3,359,000
Foreign currency translation adjustments [Member]
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	(3,738,000)	(4,633,000)	(5,819,000)	(3,305,000)
Unrealized gains (losses)	895,000	1,186,000	(2,514,000)
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	895,000	1,186,000	(2,514,000)
Defined benefit pension plans [Member]
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	(809,000)	(770,000)	785,000	$ (5,088,000)
Unrealized gains (losses)	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	152,000	(1,551,000)	6,291,000
Tax effect	(39,000)	143,000	(145,000)
Unrecognized amounts from defined benefit pension plans	(259,000)	(323,000)	(279,000)
Tax effect	107,000	176,000	6,000
Net of tax amount	$ (39,000)	$ (1,555,000)	$ 5,873,000

The Davey 401KSOP and Employe_2

The Davey 401KSOP and Employee Stock Ownership Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Employee stock ownership plan (ESOP), initial shares in ESOP	120,000
Employee Stock Ownership Plan (ESOP), Shares Adjusted for Stock Splits	23,040,000
Employee stock ownership plan (ESOP), initial value in ESOP	$ 2,700
Defined contribution plan, employer matching contribution, percent	4.00%
Defined contribution plan, eligible age	21 years
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	$ 3,298	$ 4,749
Company shares held in 401KSOP and ESOP, fair value	150,089	119,806
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP):	153,387	124,555
Employee retirement plan, employer match	$ 7,687	$ 4,600	$ 4,053
First 3% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	100.00%
3% to 5% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	50.00%
Maximum [Member] | First 3% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	3.00%
Maximum [Member] | 3% to 5% [Member]
Employee Stock Ownership Plan (ESOP) disclosures [Line Items]
Defined contribution plan, employer matching contribution, percent	2.00%

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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%
Salary and Wage, Excluding Cost of Good and Service Sold [Abstract]
Compensation expense	$ 3,407	$ 2,845	$ 3,370
Income tax benefit	$ 538	$ 404	$ 602
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Volatility rate	9.70%	9.90%	10.10%
Risk-free interest rate	0.70%	2.30%	2.70%
Expected dividend yield	0.40%	0.70%	0.70%
Expected life of awards (years)	8 years 1 month 6 days	8 years 9 months 18 days	9 years 2 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercisable, ending balance	940,277
Excess tax benefits	$ 530	$ 1,181	$ 453
Employee stock option [Member]
Salary and Wage, Excluding Cost of Good and Service Sold [Abstract]
Compensation expense	$ 517	$ 550	663
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Vesting period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance	1,428,082
Granted	174,897
Exercised	(166,675)
Forfeited	27,645
Outstanding, ending balance	1,408,659	1,428,082
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercisable, ending balance	940,277
Outstanding, weighted average exercise price, ending balance	$ 16.67	$ 15.13
Granted, weighted average exercise price	24.20
Exercised, weighted average exercise price	11.30
Forfeited, weighted average exercise price	16.79
Exercisable, weighted average exercise price	$ 14.54
Outstanding, weighted average remaining contractual life	5 years 7 months 6 days
Exercisable, weighted average remaining contractual life (years)	4 years 3 months 18 days
Unrecognized compensation cost	$ 1,298
Outstanding, aggregate intrinsic value	11,593
Exercisable, aggregate intrinisic value	$ 9,743
Number outstanding	1,408,659
Outstanding options, weighted average exercise price	$ 16.67
Number exercisable	940,277
Exercisable options, weighted average exercise price	$ 14.54
Stock Appreciation Rights (SARs) [Member]
Salary and Wage, Excluding Cost of Good and Service Sold [Abstract]
Compensation expense	$ 282	$ 363	540
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning balance	262,705
Granted	0
Forfeited	2,254
Vested	(155,215)
Unvested, ending balance	105,236	262,705
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	$ 3.47
Granted, weighted average award date value	0
Forfeited, weighted average award date value	3.53
Vested, weighted average award date value	3.29
Unvested, weighted average award date value, ending balance	$ 3.73	$ 3.47
Weighted average remaining contractual life (years)	1 year 7 months 6 days
Unrecognized compensation cost	$ 241
Aggregate intrinsic value, unvested	2,620
Restricted Stock Units (RSUs) [Member]
Salary and Wage, Excluding Cost of Good and Service Sold [Abstract]
Compensation expense	$ 1,166	$ 814	1,169
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning balance	224,259
Granted	98,863
Forfeited	1,871
Vested	(65,944)
Unvested, ending balance	255,307	224,259
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	$ 17.11
Granted, weighted average award date value	23.74
Forfeited, weighted average award date value	17.37
Vested, weighted average award date value	15.52
Unvested, weighted average award date value, ending balance	$ 20.09	$ 17.11
Weighted average remaining contractual life (years)	2 years 4 months 24 days
Unrecognized compensation cost	$ 2,778
Aggregate intrinsic value, unvested	$ 6,357
Employee PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted	86,959
Unvested, ending balance	220,157
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	$ 19.92
Weighted average remaining contractual life (years)	2 years 8 months 12 days
Unrecognized compensation cost	$ 2,403
Aggregate intrinsic value, unvested	$ 5,482
Nonemployee Director RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted	11,904
Unvested, ending balance	35,150
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	$ 21.14
Weighted average remaining contractual life (years)	1 year 4 months 24 days
Unrecognized compensation cost	$ 375
Aggregate intrinsic value, unvested	$ 875
$11.60 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	212,480
Weighted average remaining contractual life (years)	2 years 6 months
Outstanding options, weighted average exercise price	$ 11.60
Number exercisable	212,480
Exercisable options, weighted average exercise price	$ 11.60
Lower range limit	11.60
Upper range limit	$ 11.60
$13.20 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	240,084
Weighted average remaining contractual life (years)	3 years 6 months
Outstanding options, weighted average exercise price	$ 13.20
Number exercisable	240,084
Exercisable options, weighted average exercise price	$ 13.20
Lower range limit	13.20
Upper range limit	$ 13.20
$15.05 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	191,265
Weighted average remaining contractual life (years)	4 years 6 months
Outstanding options, weighted average exercise price	$ 15.05
Number exercisable	191,265
Exercisable options, weighted average exercise price	$ 15.05
Lower range limit	15.05
Upper range limit	$ 15.05
$16.35 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	210,165
Weighted average remaining contractual life (years)	5 years 6 months
Outstanding options, weighted average exercise price	$ 16.35
Number exercisable	159,165
Exercisable options, weighted average exercise price	$ 16.35
Lower range limit	16.35
Upper range limit	$ 16.35
$17.60 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	121,550
Weighted average remaining contractual life (years)	6 years 6 months
Outstanding options, weighted average exercise price	$ 17.60
Number exercisable	73,650
Exercisable options, weighted average exercise price	$ 17.60
Lower range limit	17.60
Upper range limit	$ 17.60
$19.10 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	127,950
Weighted average remaining contractual life (years)	7 years 6 months
Outstanding options, weighted average exercise price	$ 19.10
Number exercisable	42,000
Exercisable options, weighted average exercise price	$ 19.10
Lower range limit	19.10
Upper range limit	$ 19.10
$21.10 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	26,500
Weighted average remaining contractual life (years)	8 years 2 months 12 days
Outstanding options, weighted average exercise price	$ 21.10
Number exercisable	4,260
Exercisable options, weighted average exercise price	$ 21.10
Lower range limit	21.10
Upper range limit	$ 21.10
$21.10 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	112,068
Weighted average remaining contractual life (years)	8 years 6 months
Outstanding options, weighted average exercise price	$ 21.10
Number exercisable	17,373
Exercisable options, weighted average exercise price	$ 21.10
Lower range limit	21.10
Upper range limit	$ 21.10
$24.20 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	28,397
Weighted average remaining contractual life (years)	9 years 6 months
Outstanding options, weighted average exercise price	$ 24.20
Number exercisable	0
Exercisable options, weighted average exercise price	$ 24.20
Lower range limit	24.20
Upper range limit	$ 24.20
$24.20 [Member] | Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number outstanding	138,200
Weighted average remaining contractual life (years)	9 years 2 months 12 days
Outstanding options, weighted average exercise price	$ 24.20
Number exercisable	0
Exercisable options, weighted average exercise price	$ 24.20
Lower range limit	24.20
Upper range limit	$ 24.20
The Davey Employee Stock Purchase Plan [Member]
Salary and Wage, Excluding Cost of Good and Service Sold [Abstract]
Compensation expense	$ 1,442	$ 1,118	$ 998
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%

Defined Benefit Pension Plans C

Defined Benefit Pension Plans Change in benefit obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined benefit plan, change in benefit obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 3,265	$ 7,064
Service cost	0	45
Interest cost	105	170
Actuarial (gains)/losses	259	323
Settlements	0	(1,677)
Benefits paid	(158)	(2,660)
Projected benefit obligation at end of year	3,471	3,265
Accumulated benefit obligation at end of year	$ 3,471	$ 3,265

Defined Benefit Pension Plans_2

Defined Benefit Pension Plans Change in fair value of plan assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Defined benefit plan, change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 0	$ 3,758
Employer contributions	158	579
Settlements	0	(1,677)
Defined Benefit Plan, Plan Assets, Benefits Paid	(158)	(2,660)
Fair value of plan assets at end of year	$ 0	$ 0
Employee retirement plan [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, number of employees settled	231

Defined Benefit Pension Plans F

Defined Benefit Pension Plans Funded status of the plans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0	$ 3,758
Projected benefit obligation	3,471	3,265	$ 7,064
Funded status of the plans	(3,471)	(3,265)
Supplemental Employee Retirement Plan [Member]
Defined benefit plan disclosure [Line Items]
Funded status of the plans	(3,019)	(2,833)
Other Postretirement Benefits Plan [Member]
Defined benefit plan disclosure [Line Items]
Funded status of the plans	$ (452)	$ (432)

Defined Benefit Pension Plans A

Defined Benefit Pension Plans Amounts reported in the consolidated balance sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined benefit plan disclosure [Line Items]
Current liability	$ (203)	$ (202)
Noncurrent liability	(3,268)	(3,063)
Funded status of the plans	$ (3,471)	$ (3,265)

Defined Benefit Pension Plans_3

Defined Benefit Pension Plans Amounts reported in accumulated other comprehensive income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	$ 892	$ 723
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax	737	638
Unrecognized prior service cost, pretax	87	150
Unrecognized prior service cost, net of tax	72	132
Amounts reported in accumulated other comprehensive income, pretax	979	873
Amounts reported in accumulated other comprehensive income, net of tax	809	770
Amortization of Costs Expected to be Recognized Next Year
Defined Benefit Plan Amortization Of Net Gains (Losses), Before Tax	(138)
Unrecognized net actuarial loss, net of tax	(100)
Unrecognized prior service cost, pretax	63
Unrecognized prior service cost, net of tax	46
Amortization of costs expected to be recognized next year, pretax	201
Amortization of costs expected to be recognized next year, net of tax	146
For pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	3,471	3,265	$ 7,064
Accumulated benefit obligation	3,471	3,265
Fair value of plan assets	$ 0	$ 0	$ 3,758

Defined Benefit Pension Plans_4

Defined Benefit Pension Plans Actuarial Assumptions (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined benefit plan disclosure [Line Items]
SERP	3.34%	3.34%	4.37%
Restoration Plan	3.23%	3.23%	4.28%

Defined Benefit Pension Plans_5

Defined Benefit Pension Plans Components of Pension Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs--increase in benefit obligation earned	$ 0	$ 75	$ 400
Interest cost on projected benefit obligation	105	198	718
Expected return on plan assets	0	(59)	(231)
Settlement loss	0	1,677	5,499
Amortization of net actuarial loss	89	87	728
Amortization of prior service cost	64	64	64
Net pension expense of defined benefit pension plans	$ 258	$ 2,042	$ 7,178
Employee retirement plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, number of employees settled	231

Defined Benefit Pension Plans_6

Defined Benefit Pension Plans Fair Value of Plan Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined benefit plan disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0	$ 3,758
Employee retirement plan [Member]
Defined benefit plan disclosure [Line Items]
Defined benefit plan, number of employees settled	231

Defined Benefit Pension Plans E

Defined Benefit Pension Plans Expected Benefits (Details) $ in Thousands	Dec. 31, 2020USD ($)
Defined benefit plan disclosure [Line Items]
Year ending December 31, 2021	$ 205
2022	202
2023	198
2024	194
2025	189
Years 2026 to 2030	$ 988

Defined Benefit Pension Plans M

Defined Benefit Pension Plans Multiemployer Pension Plans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 3,400	$ 1,094	$ 910
National Electric Benefit Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 3,239	904	768
Eighth District Electrical Pension Fund [Member]
Multiemployer Plans [Line Items]
Number of collective-bargaining agreements	1
Multiemployer Plan, Employer Contribution, Cost	$ 161	$ 190	$ 142

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Income before income taxes
Income before income taxes	$ 83,882	$ 53,678	$ 36,743
Provision for income taxes
Federal	22,093	7,934	3,165
State	6,260	3,624	2,290
Canadian	(50)	(328)	50
Total current	28,303	11,230	5,505
Deferred taxes	(5,358)	1,398	3,880
Total taxes on income	$ 22,945	$ 12,628	$ 9,385
Tax rate reconciliation
Statutory U.S. federal tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	5.20%	5.60%	5.70%
Effect of Canadian income taxes	0.20%	0.00%	0.10%
Nondeductible expenses	1.30%	2.20%	2.10%
Stock compensation	(0.30%)	(1.80%)	(0.70%)
ESOP dividend deduction	(0.10%)	(0.20%)	(0.30%)
Uncertain tax adjustments and audit settlement	0.10%	0.20%	(3.80%)
Pension termination	0.00%	(2.90%)	0.00%
All other, net	0.00%	(0.70%)	1.40%
Effective income tax rate	27.40%	23.40%	25.50%
Noncurrent deferred tax assets and liabilities, net
Self-insurance accruals				$ 22,847	$ 20,120
Accrued compensated absences				1,876	1,389
Accrued expenses and other liabilities				942	841
Accrued stock compensation				2,105	1,906
Foreign tax credit carryforward				1,597	2,137
Other future deductible amounts, net				4,076	4,167
Deferred tax assets, gross,noncurrent				33,443	30,560
Less deferred tax asset valuation allowance				1,185	1,683
Deferred tax assets, net--noncurrent				32,258	28,877
Intangibles				1,407	1,065
Prepaid expenses				4,243	3,701
Property and equipment				22,441	24,049
Deferred tax liabilities, gross, noncurrent				28,091	28,815
Net deferred tax asset--noncurrent				4,167	62
Undistributed earnings of foreign subsidiaries				29,390
Unrecognized benefits and related interest and penalties
Unrecognized tax benefits	$ 1,850	$ 1,325	$ 2,581	1,183	1,850
Portion, if recognized, would reduce tax expense and effective tax rate				735	654
Accrued interest on unrecognized tax benefits				$ 72	$ 64
Reconciliation of unrecognized tax benefits
Balance, beginning of year	1,850	1,325	2,581
Additions based on tax positions related to the current year	0	(547)	(224)
Reductions based on tax positions related to the current year	(187)	0	0
Additions for tax positions of prior years	101	23	20
Reductions for tax positions of prior years	0	0	1,500
Lapses in statutes of limitations	(581)	(45)	0
Balance, end of year	1,183	1,850	1,325
United States
Income before income taxes
Income before income taxes	82,382	54,569	36,624
Canada
Income before income taxes
Income before income taxes	$ 1,500	$ (891)	$ 119

Earnings Per Share Informatio_2

Earnings Per Share Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 6,542	$ 24,535	$ 29,881	$ (21)	$ 8,516	$ 13,397	$ 19,729	$ (593)	$ 60,937	$ 41,050	$ 27,358
Weighted-average shares, basic
Outstanding									21,981,950	22,906,264	23,698,478
Partially-paid share subscriptions									0	0	690,260
Basic weighted-average shares									21,981,950	22,906,264	24,388,738
Weighted-average shares, diluted
Exercise of stock subscription purchase rights									0	54,961	141,287
Exercise of stock options and awards									1,051,136	1,016,864	950,593
Diluted weighted-average shares									23,033,086	23,978,089	25,480,618
Earnings per share--basic	$ 0.39	$ 1.07	$ 1.31	$ 0	$ 0.37	$ 0.59	$ 0.86	$ (0.03)	$ 2.77	$ 1.79	$ 1.12
Earnings per share--diluted	$ 0.37	$ 1.03	$ 1.25	$ 0	$ 0.35	$ 0.56	$ 0.82	$ (0.03)	$ 2.65	$ 1.71	$ 1.07

Operations by Business Segmen_3

Operations by Business Segment and Geographic Information Operations by Busines Segment (Details) $ in Thousands		3 Months Ended									12 Months Ended
		Dec. 31, 2020USD ($)		Sep. 26, 2020USD ($)	Jun. 27, 2020USD ($)	Mar. 28, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 28, 2019USD ($)	Jun. 29, 2019USD ($)	Mar. 30, 2019USD ($)	Dec. 31, 2020USD ($)		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments											2
Revenues		$ 342,572		$ 337,453	$ 319,247	$ 288,280	$ 286,924	$ 307,473	$ 301,434	$ 247,889	$ 1,287,552		$ 1,143,720	$ 1,024,791
Income from operations		10,718		$ 35,372	$ 44,389	$ 3,722	14,128	$ 22,727	$ 30,288	$ 2,813	94,201		69,956	54,937
Interest expense											6,899		8,514	7,039
Interest income											2,135		348	350
Other											(5,555)		(8,112)	(11,505)
Income before income taxes											83,882		53,678	36,743
Depreciation											53,888		57,292	54,914
Amortization											2,827		2,545	2,055
Capital expenditures											51,650		58,665	60,410
Segment assets, total		655,354					596,924				655,354		596,924	526,623
Utility Services
Segment Reporting Information [Line Items]
Revenues											739,118		607,556	537,484
Income from operations											73,592		37,696	32,370
Depreciation											27,545		30,304	29,526
Amortization											530		474	211
Capital expenditures											22,595		26,528	32,148
Segment assets, total		280,467					267,982				280,467		267,982	239,426
Residential Commercial Services
Segment Reporting Information [Line Items]
Revenues											545,357		534,655	486,005
Income from operations											53,623		52,471	47,812
Depreciation											23,553		23,537	21,720
Amortization											2,297		2,071	1,842
Capital expenditures											21,327		24,573	22,256
Segment assets, total		238,876					226,313				238,876		226,313	208,369
All Other
Segment Reporting Information [Line Items]
Revenues											3,077		1,509	1,302
Income from operations											(25,297)		(12,963)	(20,569)
Depreciation											0		0	0
Amortization											0		0	0
Capital expenditures											0		0	0
Segment assets, total		0					0				0		0	0
Reconciling  Adjustments
Segment Reporting Information [Line Items]
Revenues											0		0	0
Income from operations											(7,717)	[1]	(7,248)	(4,676)	[1]
Interest expense											6,899		8,514	7,039
Interest income											2,135		348	350
Other											(5,555)		(8,112)	(11,505)
Depreciation	[2]										2,790		3,451	3,668
Amortization											0		0	2
Capital expenditures											7,728		7,564	6,006
Segment assets, total		$ 136,011	[3]				$ 102,629				$ 136,011	[3]	$ 102,629	$ 78,828	[3]
[1]	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 Segmen_4

Operations by Business Segment and Geographic Information Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 342,572	$ 337,453	$ 319,247	$ 288,280	$ 286,924	$ 307,473	$ 301,434	$ 247,889	$ 1,287,552	$ 1,143,720	$ 1,024,791
Long-lived assets, net	350,292				315,499				350,292	315,499	271,555
United States
Segment Reporting Information [Line Items]
Revenues									1,214,628	1,066,035	949,317
Long-lived assets, net	324,776				288,196				324,776	288,196	251,181
Canada
Segment Reporting Information [Line Items]
Revenues									72,924	77,685	75,474
Long-lived assets, net	$ 25,516				$ 27,303				$ 25,516	$ 27,303	$ 20,374

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	$ 1,287,552	$ 1,143,720	$ 1,024,791
Contract with customer, asset and liability [Abstract]
Revenue recognized	1,530	2,230
Contract liabilities - current	3,242	3,129
Contract liabilities - noncurrent	1,754	2,705
Net contract liabilities	4,996	5,834
Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	739,118	607,556	537,484
Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	545,357	534,655	486,005
All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	3,077	1,509	1,302
United States
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	1,214,628	1,066,035	949,317
United States | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	703,324	567,134	499,242
United States | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	508,227	497,392	448,773
United States | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	3,077	1,509	1,302
Canada
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	72,924	77,685	75,474
Canada | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	35,794	40,422	38,242
Canada | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	37,130	37,263	37,232
Canada | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0	0	0
Tree and plant care
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	853,382	753,582	683,901
Tree and plant care | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	535,260	448,325	394,481
Tree and plant care | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	318,061	305,365	290,940
Tree and plant care | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	61	(108)	(1,520)
Grounds maintenance
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	138,885	152,283	117,498
Grounds maintenance | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0	0	0
Grounds maintenance | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	138,885	152,283	117,498
Grounds maintenance | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0	0	0
Storm damage services
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	30,631	8,001	23,311
Storm damage services | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	20,907	3,096	13,864
Storm damage services | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	9,724	4,905	9,447
Storm damage services | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0	0	0
Consulting and other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	264,654	229,854	200,081
Consulting and other | Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	182,951	156,135	129,139
Consulting and other | Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	78,687	72,102	68,120
Consulting and other | All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	$ 3,016	$ 1,617	$ 2,822

Fair Value Measurements and F_3

Fair Value Measurements and Financial Instruments Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	$ 0	$ 62,000
Total	77,068	143,354
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	19,359	15,402
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
Deferred compensation	3,192	2,786
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
Deferred compensation	0	0
Total carrying value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	0	62,000
Senior unsecured notes	75,000	75,000
Term loans, noncurrent	2,324	6,774
Total	77,324	143,774
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	19,359	15,402
Deferred compensation	3,192	2,786
Fair value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	0	62,000
Senior unsecured notes	81,424	79,558
Term loans, noncurrent	2,451	7,124
Total	$ 83,875	$ 148,682

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loss contingency number of claims alleged	3
Letter of credit [Member]
Letters of credit outstanding	$ 88,242	$ 81,619
Customer concentration risk [Member]
Concentration risk, percentage	17.00%	12.00%
Pre-petition accounts receivable balance	$ 15,000

Quarterly Results of Operatio_3

Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 342,572	$ 337,453	$ 319,247	$ 288,280	$ 286,924	$ 307,473	$ 301,434	$ 247,889	$ 1,287,552	$ 1,143,720	$ 1,024,791
Gross profit (revenues less costs and expenses, operating)	117,500	128,815	128,265	89,675	103,962	114,280	113,662	81,720
Income from operations	10,718	35,372	44,389	3,722	14,128	22,727	30,288	2,813	94,201	69,956	54,937
Net income (loss)	$ 6,542	$ 24,535	$ 29,881	$ (21)	$ 8,516	$ 13,397	$ 19,729	$ (593)	$ 60,937	$ 41,050	$ 27,358
Net income (loss) per share -- Basic	$ 0.39	$ 1.07	$ 1.31	$ 0	$ 0.37	$ 0.59	$ 0.86	$ (0.03)	$ 2.77	$ 1.79	$ 1.12
Net income (loss) per share -- Diluted	0.37	1.03	1.25	0	0.35	0.56	0.82	(0.03)	$ 2.65	$ 1.71	$ 1.07
ESOT valuation per share	$ 30	$ 24.90	$ 24.90	$ 24.20	$ 24.20	$ 22.60	$ 22.60	$ 21.10
Increase/(decrease) in casualty insurance expense	$ 915				$ (2,077)