AAON (AAON) 10-K 27 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	0-18953
Entity Registrant Name	AAON, INC.
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	87-0448736
Entity Address, Address Line One	2425 South Yukon Ave.,
Entity Address, City or Town	Tulsa,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74107
City Area Code	918
Local Phone Number	583-2266
Title of 12(b) Security	Common Stock
Trading Symbol	AAON
Security Exchange Name	NASDAQ
Is Entity a Well-known Seasoned Issuer?	No
Is Entity a Voluntary Filer?	No
Is Entity's Reporting Status Current?	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2,035.2
Entity Common Stock, Shares Outstanding		52,092,212
Documents Incorporated by Reference	Portions of registrant’s definitive Proxy Statement to be filed in connection with the Annual Meeting of Stockholders to be held May 12, 2020, are incorporated into Part III.
Entity Central Index Key	0000824142
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Business Description

Business Description	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Description	Business Description AAON, Inc. is a Nevada corporation which was incorporated on August 18, 1987. Our operating subsidiaries include AAON, Inc., an Oklahoma corporation and AAON Coil Products, Inc., a Texas corporation (collectively, the “Company”). The Consolidated Financial Statements include our accounts and the accounts of our subsidiaries. We are engaged in the engineering, manufacturing, marketing and sale of air conditioning and heating equipment consisting of standard, semi-custom and custom rooftop units, chillers, packaged outdoor mechanical rooms, air handling units, makeup air units, energy recovery units, condensing units, geothermal/water-source heat pumps, coils and controls.

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements Changes to U.S. GAAP are established by the FASB in the form of accounting standards updates (“ASUs”) to the FASB’s Accounting Standards Codification. We consider the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on our consolidated financial statements and notes thereto. In December 2019, the FASB issued ASU 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes. The ASU includes simplification of accounting for income taxes for franchise taxes, step up in tax basis for goodwill as part of a business combination and interim reporting of enacted changes in tax laws. The ASU is effective for the Company beginning after December 15, 2020. We do not expect ASU 2019-12 will have a material effect on our consolidated financial statements and notes thereto. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurements: Changes to the Disclosure Requirement for Fair Value Measurements. The ASU includes additional disclosure requirements for unrealized gains and losses for Level 3 fair value measurement and significant observable inputs used to develop Level 3 fair value measurements. The ASU is effective for the Company beginning after December 15, 2019. We do not expect ASU 2018-13 will have a material effect on our consolidated financial statements and notes thereto.

Consolidated Balance Sheets

Consolidated Balance Sheets $ in Thousands, $ in Millions		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Current assets:
Cash and cash equivalents		$ 26,797	$ 1,994
Restricted cash		17,576	0
Accounts receivable, net		67,399	54,078
Income tax receivable		772	5,901
Note receivable		29	27
Inventories, net		73,601	77,612
Prepaid expenses and other		1,375	1,046
Total current assets		187,549	140,658
Property, plant and equipment:
Land		3,274	3,114
Buildings		101,113	97,393
Machinery and equipment		236,087	212,779
Furniture and fixtures		16,862	16,597
Total property, plant and equipment		357,336	329,883
Less: Accumulated depreciation		179,242	166,880
Property, plant and equipment, net		178,094	163,003
Intangible assets, net		272	506
Goodwill		3,229	3,229
Right of use assets		1,683
Note receivable, long-term		597	598
Total assets		371,424	307,994
Current liabilities:
Revolving credit facility		0	0
Accounts payable		11,759	10,616
Accrued liabilities		44,269	36,875
Total current liabilities		56,028	47,491
Deferred tax liabilities		15,297	9,259
Other long-term liabilities		3,639	1,801
New market tax credit obligation	[1]	6,320	0
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued		0	0
Common stock, $.004 par value, 100,000,000 shares authorized, 52,078,515 and 51,991,242 issued and outstanding at December 31, 2019 and 2018, respectively		208	208
Additional paid-in capital		3,631	0
Retained earnings		286,301	249,235
Total stockholders’ equity		290,140	249,443
Total liabilities and stockholders’ equity		$ 371,424	$ 307,994
[1]	(a) Held by variable interest entities (Note 18)

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 112,340	$ 112,937	$ 109,588	$ 99,082	$ 469,333	$ 433,947	$ 405,232
Cost of sales		86,090	89,233	88,392	84,494	80,107	81,927	83,886	349,908	330,414	281,581
Gross profit	36,381	27,410	30,204	25,430	27,846	32,830	27,661	15,196	119,425	103,533	123,651
Selling, general and administrative expenses		12,374	12,912	13,677	10,723	12,667	13,153	11,651	52,077	48,194	49,371
Loss (gain) on disposal of assets		6	6	284	(3)	2	(4)	(7)	337	(12)	45
Income from operations		15,030	17,286	11,469	17,126	20,161	14,512	3,552	67,011	55,351	74,235
Interest income, net		9	31	9	25	36	67	68	66	196	298
Other (expense) income, net		(7)	17	(26)	(58)	5	12	(6)	(46)	(47)	91
Income before taxes		15,032	17,334	11,452	17,093	20,202	14,591	3,614	67,031	55,500	74,624
Income tax provision		742	3,943	2,695	4,129	5,688	2,894	460	13,320	13,171	20,794
Net income	$ 17,273	$ 14,290	$ 13,391	$ 8,757	$ 12,964	$ 14,514	$ 11,697	$ 3,154	$ 53,711	$ 42,329	$ 53,830
Earnings per share:
Basic (usd per share)	$ 0.33	$ 0.27	$ 0.26	$ 0.17	$ 0.25	$ 0.28	$ 0.22	$ 0.06	$ 1.03	$ 0.81	$ 1.02
Diluted (usd per share)	$ 0.33	$ 0.26	0.26	$ 0.17	0.25	$ 0.27	0.22	$ 0.06	1.02	0.80	1.01
Cash dividends declared per common share (in dollars per share)			$ 0.16		$ 0.16		$ 0.16		$ 0.32	$ 0.32	$ 0.26
Weighted average shares outstanding:
Basic (in shares)		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902	52,079,865	52,284,616	52,572,496
Diluted (in shares)		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223	52,635,415	52,667,939	53,078,734

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings
Balance (in shares) at Dec. 31, 2016		52,651
Balance at Dec. 31, 2016	$ 208,410	$ 211	$ 0	$ 208,199
Net income	53,830			53,830
Stock options exercised and restricted stock awards granted (in shares)		293
Stock options exercised and restricted stock awards granted	2,259	$ 1	2,258
Share-based compensation	6,313		6,313
Stock repurchased and retired (in shares)		(522)
Stock repurchased and retired	(18,234)	$ (2)	(8,571)	(9,661)
Dividends	(13,653)			(13,653)
Balance (in shares) at Dec. 31, 2017		52,422
Balance at Dec. 31, 2017	238,925	$ 210	0	238,715
Net income	3,154
Balance at Mar. 31, 2018	242,011
Balance (in shares) at Dec. 31, 2017		52,422
Balance at Dec. 31, 2017	238,925	$ 210	0	238,715
Net income	42,329			42,329
Stock options exercised and restricted stock awards granted (in shares)		353
Stock options exercised and restricted stock awards granted	4,987	$ 1	4,986
Share-based compensation	7,862		7,862
Stock repurchased and retired (in shares)		(784)
Stock repurchased and retired	(27,943)	$ (3)	(12,848)	(15,092)
Dividends	(16,717)			(16,717)
Balance (in shares) at Dec. 31, 2018		51,991
Balance at Dec. 31, 2018	249,443	$ 208	0	249,235
Balance at Mar. 31, 2018	242,011
Net income	11,697
Balance at Jun. 30, 2018	240,833
Net income	14,514
Balance at Sep. 30, 2018	251,798
Net income	12,964
Balance (in shares) at Dec. 31, 2018		51,991
Balance at Dec. 31, 2018	249,443	$ 208	0	249,235
Net income	8,757
Balance at Mar. 31, 2019	262,546
Balance (in shares) at Dec. 31, 2018		51,991
Balance at Dec. 31, 2018	249,443	$ 208	0	249,235
Net income	53,711			53,711
Stock options exercised and restricted stock awards granted (in shares)		542
Stock options exercised and restricted stock awards granted	12,625	$ 2	12,623
Share-based compensation	11,799		11,799
Stock repurchased and retired (in shares)		(454)
Stock repurchased and retired	(20,793)	$ (2)	(20,791)	0
Dividends	(16,645)			(16,645)
Balance (in shares) at Dec. 31, 2019		52,079
Balance at Dec. 31, 2019	290,140	$ 208	3,631	286,301
Balance at Mar. 31, 2019	262,546
Net income	13,391
Balance at Jun. 30, 2019	267,511
Net income	14,290
Balance at Sep. 30, 2019	282,255
Net income	17,273
Balance (in shares) at Dec. 31, 2019		52,079
Balance at Dec. 31, 2019	$ 290,140	$ 208	$ 3,631	$ 286,301

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income	$ 53,711	$ 42,329	$ 53,830
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,766	17,655	15,007
Amortization of bond premiums	0	13	47
Amortization of debt issuance costs	7	0	0
Provision for losses on accounts receivable, net of adjustments	91	174	179
Provision for excess and obsolete inventories	1,454	152	264
Share-based compensation	11,799	7,862	6,313
Loss (gain) on disposition of assets	337	(12)	45
Foreign currency transaction (gain) loss	(27)	55	(59)
Interest income on note receivable	(25)	(27)	(25)
Deferred income taxes	6,038	2,641	(749)
Changes in assets and liabilities:
Accounts receivable	(13,412)	(2,832)	(7,516)
Income tax receivable	5,129	(4,448)	4,591
Inventories	2,557	(5,598)	(23,698)
Prepaid expenses and other	(329)	(528)	98
Accounts payable	280	(1,176)	3,043
Deferred revenue	425	412	258
Accrued liabilities and donations	7,124	(1,816)	6,366
Net cash provided by operating activities	97,925	54,856	57,994
Investing Activities
Capital expenditures	(37,166)	(37,268)	(41,713)
Cash paid in business combination	0	(6,377)	0
Proceeds from sale of property, plant and equipment	69	13	10
Investment in certificates of deposits	(6,000)	(7,200)	(5,280)
Maturities of certificates of deposits	6,000	10,080	7,912
Purchase of investments held to maturity	0	(9,001)	(13,241)
Maturities of investments held to maturity	0	14,570	19,700
Proceeds from called investments	0	495	1,500
Principal payments from note receivable	51	53	60
Net cash used in investing activities	(37,046)	(34,635)	(31,052)
Financing Activities
Proceeds from financing obligation, net of issuance costs	6,614	0	0
Payment related to financing costs	(301)	0	0
Stock options exercised	12,625	4,987	2,259
Repurchase of stock	(19,586)	(26,846)	(16,620)
Employee taxes paid by withholding shares	(1,207)	(1,097)	(1,614)
Cash dividends paid to stockholders	(16,645)	(16,728)	(13,663)
Net cash used in financing activities	(18,500)	(39,684)	(29,638)
Net increase (decrease) in cash, cash equivalents and restricted cash	42,379	(19,463)	(2,696)
Cash, cash equivalents and restricted cash, beginning of year	1,994	21,457	24,153
Cash, cash equivalents and restricted cash, end of year	$ 44,373	$ 1,994	$ 21,457

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Disaggregated net sales by major source: Years Ended December 31, 2019 2018 2017 (in thousands) Rooftop Units $ 349,427 $ 333,105 $ 317,414 Condensing Units 18,475 18,282 19,276 Air Handlers 24,265 21,905 22,570 Outdoor Mechanical Rooms 1,643 2,408 3,238 Water Source Heat Pumps 25,447 14,660 9,911 Part Sales 33,331 26,732 20,756 Other 16,745 16,855 12,067 Net Sales $ 469,333 $ 433,947 $ 405,232 Other sales include freight, extended warranties and miscellaneous revenue. Disaggregated units sold by major source: Years Ended December 31, 2019 2018 2017 Rooftop Units 14,448 15,273 16,003 Condensing Units 1,738 2,007 2,252 Air Handlers 2,372 2,500 2,577 Outdoor Mechanical Rooms 33 38 64 Water Source Heat Pumps 7,716 5,334 2,485 Total Units 26,307 25,152 23,381

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Business Combination	Business CombinationOn February 28, 2018, we closed on the purchase of substantially all of the assets of WattMaster Controls, Inc. (“WattMaster”). The assets acquired consisted primarily of intellectual property, receivables, inventory and fixed assets. The Company also hired substantially all of the WattMaster employees. These assets and workforce will allow us to accelerate the development of our own electronic controllers for air distribution systems. We funded the business combination with available cash of $6.0 million. In May 2018, we paid the final working capital settlement of $0.4 million with available cash. We have included the results of WattMaster’s operations in our consolidated financial statements beginning March 1, 2018. The following table presents the allocation of the consideration paid to the assets acquired and liabilities assumed, based on their fair values, in the acquisition of WattMaster described above: (in thousands) Accounts receivable $ 1,082 Inventories 1,380 Property, plant and equipment 340 Intellectual property 700 Goodwill 3,229 Assumed current liabilities (354) Consideration paid $ 6,377 Goodwill represents the excess of the consideration paid for the acquired businesses over the fair value of the individual assets acquired, net of liabilities assumed. Goodwill represents a premium paid to acquire the skilled workforce of the business acquired and is deductible for federal income tax purposes.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets Our intangible assets consist of the following: December 31, 2019 2018 (in thousands) Intellectual property $ 700 $ 700 Less: Accumulated amortization (428) (194) Total, net $ 272 $ 506 Amortization expense recorded in cost of sales is as follows: Years Ended December 31, 2019 2018 2017 (in thousands) Amortization expense $ 234 $ 194 $ —

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Years Ended December 31, 2019 2018 2017 Supplemental disclosures: (in thousands) Interest paid $ — $ 6 $ — Income taxes paid, net 2,172 14,979 16,951 Non-cash investing and financing activities: Non-cash capital expenditures 863 481 832

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Disaggregated net sales by major source: Years Ended December 31, 2019 2018 2017 (in thousands) Rooftop Units $ 349,427 $ 333,105 $ 317,414 Condensing Units 18,475 18,282 19,276 Air Handlers 24,265 21,905 22,570 Outdoor Mechanical Rooms 1,643 2,408 3,238 Water Source Heat Pumps 25,447 14,660 9,911 Part Sales 33,331 26,732 20,756 Other 16,745 16,855 12,067 Net Sales $ 469,333 $ 433,947 $ 405,232 Other sales include freight, extended warranties and miscellaneous revenue. Disaggregated units sold by major source: Years Ended December 31, 2019 2018 2017 Rooftop Units 14,448 15,273 16,003 Condensing Units 1,738 2,007 2,252 Air Handlers 2,372 2,500 2,577 Outdoor Mechanical Rooms 33 38 64 Water Source Heat Pumps 7,716 5,334 2,485 Total Units 26,307 25,152 23,381

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Acquisition	The following table presents the allocation of the consideration paid to the assets acquired and liabilities assumed, based on their fair values, in the acquisition of WattMaster described above: (in thousands) Accounts receivable $ 1,082 Inventories 1,380 Property, plant and equipment 340 Intellectual property 700 Goodwill 3,229 Assumed current liabilities (354) Consideration paid $ 6,377

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Our intangible assets consist of the following: December 31, 2019 2018 (in thousands) Intellectual property $ 700 $ 700 Less: Accumulated amortization (428) (194) Total, net $ 272 $ 506
Schedule of Amortization Expense	Amortization expense recorded in cost of sales is as follows: Years Ended December 31, 2019 2018 2017 (in thousands) Amortization expense $ 234 $ 194 $ —

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Years Ended December 31, 2019 2018 2017 Supplemental disclosures: (in thousands) Interest paid $ — $ 6 $ — Income taxes paid, net 2,172 14,979 16,951 Non-cash investing and financing activities: Non-cash capital expenditures 863 481 832

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stockholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.004	$ 0.004	$ 0.004
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)	52,078,515	51,991,242	52,422,801
Common stock, shares outstanding (in shares)	52,078,515	51,991,242	52,422,801

Revenue Recognition (Details)

Revenue Recognition (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)unit	Dec. 31, 2018USD ($)unit	Dec. 31, 2017USD ($)unit
Disaggregation of Revenue [Line Items]
Net sales	$ 469,333	$ 433,947	$ 405,232
Total Units | unit	26,307,000	25,152,000	23,381,000
Rooftop Units
Disaggregation of Revenue [Line Items]
Net sales	$ 349,427	$ 333,105	$ 317,414
Total Units | unit	14,448,000	15,273,000	16,003,000
Condensing Units
Disaggregation of Revenue [Line Items]
Net sales	$ 18,475	$ 18,282	$ 19,276
Total Units | unit	1,738,000	2,007,000	2,252,000
Air Handlers
Disaggregation of Revenue [Line Items]
Net sales	$ 24,265	$ 21,905	$ 22,570
Total Units | unit	2,372,000	2,500,000	2,577,000
Outdoor Mechanical Rooms
Disaggregation of Revenue [Line Items]
Net sales	$ 1,643	$ 2,408	$ 3,238
Total Units | unit	33,000	38,000	64,000
Water Source Heat Pumps
Disaggregation of Revenue [Line Items]
Net sales	$ 25,447	$ 14,660	$ 9,911
Total Units | unit	7,716,000	5,334,000	2,485,000
Part Sales
Disaggregation of Revenue [Line Items]
Net sales	$ 33,331	$ 26,732	$ 20,756
Other
Disaggregation of Revenue [Line Items]
Net sales	$ 16,745	$ 16,855	$ 12,067

Revenue Recognition (Narrative)

Revenue Recognition (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Payments to representatives	$ 46.1	$ 47.8	$ 51.8
Extended product warranties, minimum length	6 months
Extended product warranties, maximum length	10 years

Business Combination (Details)

Business Combination (Details) - USD ($) $ in Thousands	Feb. 28, 2018	May 31, 2018	Mar. 01, 2018
Business Acquisition [Line Items]
Working capital settlement paid		$ 400
WattMaster
Business Acquisition [Line Items]
Payments to acquire businesses	$ 6,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Accounts receivable			$ 1,082
Inventories			1,380
Property, plant and equipment			340
Intellectual property			700
Goodwill			3,229
Assumed current liabilities			(354)
Consideration paid			$ 6,377

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intellectual property
Intellectual property	$ 700	$ 700
Less: Accumulated amortization	(428)	(194)
Total, net	272	506
Amortization expense	$ 234	$ 194	$ 0

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental disclosures:
Interest paid	$ 0	$ 6	$ 0
Income taxes paid, net	2,172	14,979	16,951
Non-cash investing and financing activities:
Non-cash capital expenditures	$ 863	$ 481	$ 832

Error Correction

Error Correction	12 Months Ended
	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Error Correction	Error Correction We have corrected herein our consolidated financial statements at December 31, 2018 and for the years ended December 31, 2018 and December 31, 2017, in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 250, Accounting Changes and Error Corrections . The unaudited interim financial information for the quarterly periods ended September 30, 2019, June 30, 2019, March 31, 2019, December 31, 2018, September 30, 2018, June 30, 2018 and March 31, 2018, has also been corrected and is included in Note 25, Quarterly Results (Unaudited) . The 2019 quarterly corrections will be reflected in the filing of our future 2020 unaudited interim consolidated financial statement filings in Quarterly Reports on Form 10-Q. Error Correction Background The Company noted errors in previously issued financial statements relating to share-based compensation expense for stock options and restricted stock awards held by retirement eligible employees and directors. As defined by our Long-Term Incentive Plans (Note 16), stock options and restricted stock awards are fully vested when an active employee or director meets certain retirement eligibility requirements. We corrected the financial statements to recognize all share-based compensation, related to retirement eligible employees or directors, by the earlier of the grant date (if retirement eligible on grant date) or ratably from grant date to retirement eligible date. The corrected financial statements also include corrections for the tax effect of the share-based compensation corrections as well as the corrections' impact on our prior periods' employees profit sharing bonus plan (Note 17). We do not believe that the errors are quantitatively material to any period presented in our prior financial statements. However, due to the qualitative nature of the matters identified in our review, including the number of years over which the errors occurred, we determined that it would be appropriate to correct the errors in our previously issued consolidated financial statements. Accordingly, we have corrected our consolidated financial statements and the impacted amounts within the accompanying footnotes thereto. Description of Tables The following tables represent our corrected consolidated statements of income, statements of stockholders' equity, and statements of cash flows for the years ended December 31, 2018 and December 31, 2017, as well as our corrected consolidated balance sheet at December 31, 2018. The values as previously reported for years ended 2018 and 2017 were derived from our Annual Report on Form 10-K for the year ended December 31, 2018 filed on February 28, 2019. Consolidated Statements of Income Year Ended December 31, 2018 Year Ended December 31, 2017 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except per share data) Net sales $ 433,947 $ — $ 433,947 $ 405,232 $ — $ 405,232 Cost of sales 330,414 — (a) 330,414 281,835 (254) (a) 281,581 Gross profit 103,533 — 103,533 123,397 254 123,651 Selling, general and administrative expenses 47,755 439 (b) 48,194 49,249 122 (b) 49,371 (Gain) loss on disposal of assets (12) — (12) 45 — 45 Income from operations 55,790 (439) 55,351 74,103 132 74,235 Interest income, net 196 — 196 298 — 298 Other (expense) income, net (47) — (47) 91 — 91 Income before taxes 55,939 (439) 55,500 74,492 132 74,624 Income tax provision 13,367 (196) (c) 13,171 19,994 800 (c) 20,794 Net income $ 42,572 $ (243) $ 42,329 $ 54,498 $ (668) $ 53,830 Earnings per share: Basic $ 0.81 $ — $ 0.81 $ 1.04 $ (0.02) $ 1.02 Diluted $ 0.81 $ (0.01) $ 0.80 $ 1.03 $ (0.02) $ 1.01 Cash dividends declared per common share: $ 0.32 $ — $ 0.32 $ 0.26 $ — $ 0.26 Weighted average shares outstanding: Basic 52,284,616 — 52,284,616 52,572,496 — 52,572,496 Diluted 52,667,939 — 52,667,939 53,078,734 — 53,078,734 (a) The share-based compensation correction to cost of sales for the year ended December 31, 2017 was approximately$0.3 million. There was no correction required for the year ended December 31, 2018 for cost of sales. (b) The share-based compensation correction to selling, general and administrative expenses for the years ended December 31, 2018 and 2017 was approximately $0.5 million and $0.1 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the years ended December 31, 2018 and 2017, respectively. (c) The correction to income taxes is the tax affect of the share-based compensation correction discussed above. Consolidated Balance Sheets December 31, 2018 Previously Reported Corrections As Corrected Assets (in thousands, except share and per share data) Current assets: Cash and cash equivalents $ 1,994 $ — $ 1,994 Accounts receivable, net 54,078 — 54,078 Income tax receivable 6,104 (203) (a) 5,901 Note receivable 27 — 27 Inventories, net 77,612 — 77,612 Prepaid expenses and other 1,046 — 1,046 Total current assets 140,861 (203) 140,658 Property, plant and equipment: Land 3,114 — 3,114 Buildings 97,393 — 97,393 Machinery and equipment 212,779 — 212,779 Furniture and fixtures 16,597 — 16,597 Total property, plant and equipment 329,883 — 329,883 Less: Accumulated depreciation 166,880 — 166,880 Property, plant and equipment, net 163,003 — 163,003 Intangible assets, net 506 — 506 Goodwill 3,229 — 3,229 Note receivable, long-term 598 — 598 Total assets $ 308,197 $ (203) $ 307,994 Liabilities and Stockholders’ Equity Current liabilities: Revolving credit facility $ — $ — $ — Accounts payable 10,616 — 10,616 Accrued liabilities 37,455 (580) (b) 36,875 Total current liabilities 48,071 (580) 47,491 Deferred tax liabilities 10,826 (1,567) (a) 9,259 Other long-term liabilities 1,801 — 1,801 Commitments and contingencies Stockholders’ equity: Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued — — — Common stock, $.004 par value, 100,000,000 shares authorized, 51,991,242 and 52,422,801 issued and outstanding at December 31, 2018 and 2017, respectively 208 — 208 Additional paid-in capital — — — Retained earnings 247,291 1,944 (c) 249,235 Total stockholders’ equity 247,499 1,944 249,443 Total liabilities and stockholders’ equity $ 308,197 $ (203) $ 307,994 (a) The correction to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (b) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (c) See descriptions of the stockholders' equity in the consolidated statements of stockholders' equity for the year ended December 31, 2018 in sections below. Consolidated Statements of Stockholders’ Equity Common Stock Paid-in Retained Shares Amount Capital Earnings Total As Previously Reported (in thousands) Balance at December 31, 2017 52,422 $ 210 $ — $ 237,016 $ 237,226 Net income — — — 42,572 42,572 Stock options exercised and restricted 353 1 4,986 — 4,987 stock awards granted Share-based compensation — — 7,374 — 7,374 Stock repurchased and retired (784) (3) (12,360) (15,580) (27,943) Dividends — — — (16,717) (16,717) Balance at December 31, 2018 51,991 208 — 247,291 247,499 Correction Impacts Balance at December 31, 2017 — — — 1,699 1,699 Net income — — — (243) (243) Stock options exercised and restricted — — — — — stock awards granted Share-based compensation — — 488 — 488 Stock repurchased and retired — — (488) 488 — Dividends — — — — — Balance at December 31, 2018 — — — 1,944 1,944 As Corrected — Balance at December 31, 2017 52,422 210 — 238,715 238,925 Net income — — — 42,329 42,329 Stock options exercised and restricted 353 1 4,986 — 4,987 stock awards granted Share-based compensation — — 7,862 — 7,862 Stock repurchased and retired (784) (3) (12,848) (15,092) (27,943) Dividends — — — (16,717) (16,717) Balance at December 31, 2018 51,991 $ 208 $ — $ 249,235 $ 249,443 See descriptions of net income in the consolidated statement of income for the year ended December 31, 2018 in the section above. Consolidated Statements of Stockholders’ Equity Common Stock Paid-in Retained Shares Amount Capital Earnings Total As Previously Reported (in thousands) Balance at December 31, 2016 52,651 $ 211 $ — $ 205,687 $ 205,898 Net income — — — 54,498 54,498 Stock options exercised and restricted 293 1 2,258 — 2,259 stock awards granted Share-based compensation — — 6,458 — 6,458 Stock repurchased and retired (522) (2) (8,716) (9,516) (18,234) Dividends — — — (13,653) (13,653) Balance at December 31, 2017 52,422 210 — 237,016 237,226 Correction Impacts Balance at December 31, 2016 — — — 2,512 2,512 Net income — — — (668) (668) Stock options exercised and restricted — — — — — stock awards granted Share-based compensation — — (145) — (145) Stock repurchased and retired — — 145 (145) — Dividends — — — — — Balance at December 31, 2017 — — — 1,699 1,699 As Corrected Balance at December 31, 2016 52,651 211 — 208,199 208,410 Net income — — — 53,830 53,830 Stock options exercised and restricted 293 1 2,258 — 2,259 stock awards granted Share-based compensation — — 6,313 — 6,313 Stock repurchased and retired (522) (2) (8,571) (9,661) (18,234) Dividends — — — (13,653) (13,653) Balance at December 31, 2017 52,422 $ 210 $ — $ 238,715 $ 238,925 See descriptions of net income in the consolidated statement of income for the year ended December 31, 2017 in the section above. Consolidated Statements of Cash Flows Year Ended December 31, 2018 Year Ended December 31, 2017 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected Operating Activities (in thousands) Net income $ 42,572 $ (243) $ 42,329 $ 54,498 $ (668) $ 53,830 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 17,655 — 17,655 15,007 — 15,007 Amortization of bond premiums 13 — 13 47 — 47 Provision for losses on accounts receivable, net of adjustments 174 — 174 179 — 179 Provision for excess and obsolete inventories 152 — 152 264 — 264 Share-based compensation 7,374 488 7,862 6,458 (145) 6,313 (Gain) loss on disposition of assets (12) — (12) 45 — 45 Foreign currency transaction loss (gain) 55 — 55 (59) — (59) Interest income on note receivable (27) — (27) (25) — (25) Deferred income taxes 2,849 (208) 2,641 (1,554) 805 (749) Changes in assets and liabilities: Accounts receivable (2,832) — (2,832) (7,516) — (7,516) Income tax receivable (4,461) 13 (4,448) 4,596 (5) 4,591 Inventories (5,598) — (5,598) (23,698) — (23,698) Prepaid expenses and other (528) — (528) 98 — 98 Accounts payable (1,176) — (1,176) 3,043 — 3,043 Deferred revenue 412 — 412 258 — 258 Accrued liabilities and donations (1,766) (50) (1,816) 6,353 13 6,366 Net cash provided by operating activities 54,856 — 54,856 57,994 — 57,994 Investing Activities Capital expenditures (37,268) — (37,268) (41,713) — (41,713) Cash paid in business combination (6,377) — (6,377) — — — Proceeds from sale of property, plant and equipment 13 — 13 10 — 10 Investment in certificates of deposits (7,200) — (7,200) (5,280) — (5,280) Maturities of certificates of deposits 10,080 — 10,080 7,912 — 7,912 Purchases of investments held to maturity (9,001) — (9,001) (13,241) — (13,241) Maturities of investments held to maturity 14,570 — 14,570 19,700 — 19,700 Proceeds from called investments 495 — 495 1,500 — 1,500 Principal payments from note receivable 53 — 53 60 — 60 Net cash used in investing activities (34,635) — (34,635) (31,052) — (31,052) Financing Activities Stock options exercised 4,987 — 4,987 2,259 — 2,259 Repurchase of stock (26,846) — (26,846) (16,620) — (16,620) Employee taxes paid by withholding shares (1,097) — (1,097) (1,614) — (1,614) Cash dividends paid to stockholders (16,728) — (16,728) (13,663) — (13,663) Net cash used in financing activities (39,684) — (39,684) (29,638) — (29,638) Net decrease in cash and cash equivalents (19,463) — (19,463) (2,696) — (2,696) Cash and cash equivalents, beginning of year 21,457 — 21,457 24,153 — 24,153 Cash and cash equivalents, end of year $ 1,994 $ — $ 1,994 $ 21,457 $ — $ 21,457

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation These financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated. Our financial statements consolidate all of our affiliated entities in which we have a controlling financial interest. Because we hold certain rights that give us the power to direct the activities of two variable interest entities ("VIEs") (Note 18) that most significantly impact the VIEs economic performance, combined with a variable interest that gives us the right to receive potentially significant benefits or the obligation to absorb potentially significant losses, we have a controlling financial interest in those VIEs. Cash and Cash Equivalents We consider all highly liquid temporary investments with original maturity dates of three months or less to be cash equivalents. Cash and cash equivalents consist of bank deposits and highly liquid, interest-bearing money market funds. The Company’s cash and cash equivalents are held in a few financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected. Restricted Cash Restricted cash held at December 31, 2019 consist of bank deposits and highly liquid, interest-bearing money market funds held for the purpose of the Company's qualified New Markets Tax Credit program (Note 19) to benefit an investment in plant and equipment to facilitate the expansion of our Longview, Texas manufacturing operations. The Company’s restricted cash is held in a financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected. Certificates of Deposit We held no certificates of deposit at December 31, 2019 and 2018. Investments Held to Maturity At December 31, 2019 and 2018, we held no investments. We record the amortized cost basis and accrued interest of the corporate notes and bonds in the Consolidated Balance Sheets. We record the interest and amortization of bond premium to interest income in the Consolidated Statements of Income. Accounts and Note Receivable Accounts and note receivable are stated at amounts due from customers, net of an allowance for doubtful accounts. We generally do not require that our customers provide collateral. The Company determines its allowance for doubtful accounts by considering a number of factors, including the credit risk of specific customers, the customer’s ability to pay current obligations, historical trends, economic and market conditions and the age of the receivable. Accounts are considered past due when the balance has been outstanding for ninety days past negotiated credit terms. Past due accounts are generally written-off against the allowance for doubtful accounts only after all collection attempts have been exhausted. Concentration of Credit Risk Our customers are concentrated primarily in the domestic commercial and industrial new construction and replacement markets. To date, our sales have been primarily to the domestic market, with foreign sales accounting for approximately 3%, 3% and 4% of revenues for the years ended December 31, 2019, 2018, and 2017, respectively. One customer, Texas AirSystems, accounted for approximately 10% of our sales during 2019, 2018 and 2017. No other customer accounted for more than 5% of our sales during 2019, 2018 and 2017. One customer, Texas AirSystems, accounted for approximately 10% of our accounts receivable balance at December 31, 2019. No other customer accounted for 5% or more of our accounts receivable balance at December 31, 2019 and 2018. Inventories Inventories are valued at the lower of cost or net realizable value using the first-in, first-out (“FIFO”) method. Cost in inventory includes purchased parts and materials, direct labor and applied manufacturing overhead. We establish an allowance for excess and obsolete inventories based on product line changes, the feasibility of substituting parts and the need for supply and replacement parts. Property, Plant and Equipment Property, plant and equipment, including significant improvements, are recorded at cost, net of accumulated depreciation. Repairs and maintenance and any gains or losses on disposition are included in operations. Depreciation is computed using the straight-line method over the following estimated useful lives: Buildings 3 - 40 years Machinery and equipment 3 - 15 years Furniture and fixtures 3 - 7 years Business Combinations We record the assets acquired and liabilities assumed in a business combination at their acquisition date fair values. Fair Value Financial Instruments and Measurements The carrying amounts of cash and cash equivalents, receivables, accounts payable and accrued liabilities approximate fair value because of the short-term maturity of the items. The carrying amount of the Company’s revolving line of credit, and other payables, approximate their fair values either due to their short term nature, the variable rates associated with the debt or based on current rates offered to the Company for debt with similar characteristics. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Fair value is based upon assumptions that market participants would use when pricing an asset or liability. We use the following fair value hierarchy, which prioritizes valuation technique inputs used to measure fair value into three broad levels: • Level 1: Quoted prices in active markets for identical assets and liabilities that we have the ability to access at the measurement date. • Level 2: Inputs (other than quoted prices included within Level 1) that are either directly or indirectly observable for the asset or liability, including (i) quoted prices for similar assets or liabilities in active markets, (ii) quoted prices for identical or similar assets or liabilities in inactive markets, (iii) inputs other than quoted prices that are observable for the asset or liability, and (iv) inputs that are derived from observable market data by correlation or other means. • Level 3: Unobservable inputs for the asset or liability including situations where there is little, if any, market activity for the asset or liability. Items categorized in Level 3 include the estimated business combination fair values of property, plant and equipment, intangible assets and goodwill. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to a fair value measurement requires judgment, considering factors specific to the asset or liability. Intangible Assets Our intangible assets include various trademarks, service marks and technical knowledge acquired in our February 2018 business combination (Note 5). We amortize our intangible assets on a straight-line basis over the estimated useful lives of the assets. We evaluate the carrying value of our amortizable intangible assets for potential impairment when events and circumstances warrant such a review. Goodwill Goodwill represents the excess of the consideration paid for the acquired businesses over the fair value of the individual assets acquired, net of liabilities assumed. Goodwill at December 31, 2019 is deductible for income tax purposes. Goodwill is not amortized, but instead is evaluated for impairment at least annually. We perform our annual assessment of impairment during the fourth quarter of our fiscal year, and more frequently if circumstances warrant. To perform this assessment, we first consider qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit exceeds its carrying amount. If we conclude that it is more likely than not that the fair value of a reporting unit does not exceed its carrying amount, we calculate the fair value for the reporting unit and compare the amount to its carrying amount, including goodwill. If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not considered impaired. If the carrying amount of a reporting unit exceeds its fair value, goodwill is considered to be impaired and the goodwill balance is reduced by the difference between the fair value and carrying amount of the reporting unit. We performed a qualitative assessment as of December 31, 2019 to determine whether it was more likely than not that the fair value of the reporting unit was greater than the carrying value of the reporting unit. Based on these qualitative assessments, we determined that the fair value of the reporting unit was more likely than not greater than the carrying value of the reporting unit. Estimates and assumptions used to perform the impairment evaluation are inherently uncertain and can significantly affect the outcome of the analysis. The estimates and assumptions we use in the annual goodwill impairment assessment included market participant considerations and future forecasted operating results. Changes in operating results and other assumptions could materially affect these estimates. Impairment of Long-Lived Assets We review long-lived assets for possible impairment when events or changes in circumstances indicate, in management’s judgment, that the carrying amount of an asset may not be recoverable. Recoverability is measured by a comparison of the carrying amount of an asset or asset group to its estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the undiscounted cash flows are less than the carrying amount of the asset or asset group, an impairment loss is recognized for the amount by which the carrying amount of the asset or asset group exceeds its fair value. Research and Development The costs associated with research and development for the purpose of developing and improving new products are expensed as incurred. For the years ended December 31, 2019, 2018, and 2017 research and development costs amounted to approximately $14.8 million, $13.5 million, and $13.0 million, respectively. Advertising Advertising costs are expensed as incurred. Advertising expense for the years ended December 31, 2019, 2018, and 2017 was approximately $0.8 million, $0.8 million, and $1.7 million, respectively. Shipping and Handling We incur shipping and handling costs in the distribution of products sold that are recorded in cost of sales. Shipping charges that are billed to the customer are recorded in revenues and as an expense in cost of sales. For the years ended December 31, 2019, 2018, and 2017 shipping and handling fees amounted to approximately $14.4 million, $12.6 million, and $11.4 million, respectively. Income Taxes Income taxes are accounted for under the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the book carrying amounts and the tax basis of assets and liabilities. Excess tax benefits and deficiencies are reported as an income tax benefit or expense on the statement of income and are treated as discrete items to the income tax provision in the reporting period in which they occur. We establish accruals for unrecognized tax positions when it is more likely than not that our tax return positions may not be fully sustained. The Company records a valuation allowance for deferred tax assets when, in the opinion of management, it is more likely than not that deferred tax assets will not be realized. Share-Based Compensation The Company recognizes expense for its share-based compensation based on the fair value of the awards that are granted. The Company’s share-based compensation plans provide for the granting of stock options and restricted stock. The fair values of stock options are estimated at the date of grant using the Black-Scholes-Merton option valuation model. The use of the Black-Scholes-Merton option valuation model requires the input of subjective assumptions. The fair value of restricted stock awards is based on the fair market value of AAON common stock on the respective grant dates, reduced for the present value of dividends. Compensation expense is recognized on a straight-line basis over the service period of the related share-based compensation award. Stock options and restricted stock awards, granted to employees, vest at a rate of 20% per year. Restricted stock awards granted to directors historically vest one-third each year or, if granted on or after May 2019, vest over the shorter of directors' remaining elected term or one-third each year. If the employee or director is retirement eligible (as defined by the Long Term Incentive Plans) or becomes retirement eligible during service period of the related share-based compensation award, the service period is the lesser of 1) the grant date, if retirement eligible on grant date, or 2) the period between grant date and retirement eligible date. Forfeitures are accounted for as they occur. Derivative Instruments In the course of normal operations, the Company occasionally enters into contracts such as forward priced physical contracts for the purchase of raw materials that qualify for and are designated as normal purchase or normal sale contracts. Such contracts are exempted from the fair value accounting requirements and are accounted for at the time product is purchased or sold under the related contract. The Company does not engage in speculative transactions, nor does the Company hold or issue financial instruments for trading purposes. Revenue Recognition On January 1, 2018, we adopted the new accounting standard FASB ASC Topic 606, Revenue from Contracts with Customers , and all the related amendments to all contracts using the retrospective method. The impact at adoption was not material to the consolidated financial statements. The new accounting policy provides results substantially consistent with prior revenue recognition policies. The Company recognizes revenue when it satisfies the performance obligation in its contracts. Most of the Company’s products are highly customized, cannot be resold to other customers and the cost of rework to be resold is not economical. The Company has a formal cancellation policy and generally does not accept returns on these units. As a result, many of the Company’s products do not have an alternative use and therefore, for these products we recognize revenue over the time it takes to produce the unit. For all other products that are part sales or standardized units, we satisfy the performance obligation when the control is passed to the customer, generally at time of shipment. Final sales prices are fixed based on purchase orders. Sales allowances and customer incentives are treated as reductions to sales and are provided for based on historical experiences and current estimates. Sales of our products are moderately seasonal with the peak period being July - November of each year. In addition, the Company presents revenues net of sales tax and net of certain payments to our independent manufacturer representatives (“Representatives”). Representatives are national companies that are in the business of providing HVAC units and other related products and services to customers. The end user customer orders a bundled group of products and services from the Representative and expects the Representative to fulfill the order. Only after the specifications are agreed to by the Representative and the customer, and the decision is made to use an AAON HVAC unit, will we receive notice of the order. We establish the amount we must receive for our HVAC unit (“minimum sales price”), but do not control the total order price that is negotiated by the Representative with the end user customer. We are responsible for billings and collections resulting from all sales transactions, including those initiated by our Representatives. The Representatives submit the total order price to us for invoicing and collection. The total order price includes our minimum sales price and an additional amount which may include both the Representatives’ fee and amounts due for additional products and services required by the customer. These additional products and services may include controls purchased from another manufacturer to operate the unit, start-up services, and curbs for supporting the unit (“Third Party Products”). All are associated with the purchase of a HVAC unit but may be provided by the Representative or another third party. The Company is under no obligation related to Third Party Products. The Representatives’ fee and Third Party Products amounts (“Due to Representatives”) are paid only after all amounts associated with the order are collected from the customer. The amount of payments to our representatives was $46.1 million, $47.8 million, and $51.8 million for each of the years ended December 31, 2019, 2018, and 2017, respectively. The Company also sells extended warranties on parts for various lengths of time ranging from six Insurance Reserves Under the Company’s insurance programs, coverage is obtained for significant liability limits as well as those risks required to be insured by law or contract. It is the policy of the Company to self-insure a portion of certain expected losses related primarily to workers’ compensation and medical liability. Provisions for losses expected under these programs are recorded based on the Company’s estimates of the aggregate liabilities for the claims incurred. Product Warranties A provision is made for the estimated cost of maintaining product warranties to customers at the time the product is sold based upon historical claims experience by product line. The Company records a liability and an expense for estimated future warranty claims based upon historical experience and management’s estimate of the level of future claims. Changes in the estimated amounts recognized in prior years are recorded as an adjustment to the liability and expense in the current year. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Because these estimates and assumptions require significant judgment, actual results could differ from those estimates and could have a significant impact on our results of operations, financial position and cash flows. We reevaluate our estimates and assumptions as needed, but at a minimum on a quarterly basis. The most significant estimates include, but are not limited to, the allowance for doubtful accounts, inventory reserves,

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases We adopted ASU No. 2016-02, Leases (Topic 842) , as amended, as of January 1, 2019, using the transition method, which becomes effective upon the date of adoption. The transition method allows entities to initially apply the new leases standard at the adoption date (January 1, 2019) and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed us to carry forward the historical lease classification. We have also elected the short-term lease measurement and recognition exemption which does not require balance sheet presentation for short-term leases. The Company historically does not enter into numerous or material lease agreements to support its manufacturing operations. Furthermore, any lease agreements entered into are usually less than a year and for leases on non material assets such as warehouse vehicles and office equipment.

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Accounts Receivable	Accounts Receivable Accounts receivable and the related allowance for doubtful accounts are as follows: December 31, 2019 2018 (in thousands) Accounts receivable $ 67,752 $ 54,342 Less: Allowance for doubtful accounts (353) (264) Total, net $ 67,399 $ 54,078 Years Ended December 31, 2019 2018 2017 Allowance for doubtful accounts: (in thousands) Balance, beginning of period $ 264 $ 119 $ 90 Provisions for losses on accounts receivable, net of adjustments 91 174 179 Accounts receivable written off, net of recoveries (2) (29) (150) Balance, end of period $ 353 $ 264 $ 119

Inventories

Inventories	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories The components of inventories and the related changes in the allowance for excess and obsolete inventories are as follows: December 31, 2019 2018 (in thousands) Raw materials $ 68,842 $ 67,995 Work in process 1,825 4,060 Finished goods 5,578 6,767 76,245 78,822 Less: Allowance for excess and obsolete inventories (2,644) (1,210) Total, net $ 73,601 $ 77,612 Years Ended December 31, 2019 2018 2017 Allowance for excess and obsolete inventories: (in thousands) Balance, beginning of period $ 1,210 $ 1,118 $ 1,382 Provisions for excess and obsolete inventories 1,454 152 102 Inventories written off (20) (60) (366) Balance, end of period $ 2,644 $ 1,210 $ 1,118

Note Receivable

Note Receivable	12 Months Ended
	Dec. 31, 2019
Note Receivable [Abstract]
Note Receivable	Note Receivable In connection with the closure of our Canadian facility on May 18, 2009, we sold land and a building in September 2010 and assumed a note receivable from the borrower secured by the property. The C$1.1 million, 15 year note has an interest rate of 4.0% and is payable to us monthly, and has a C$0.6 million balloon payment due in October 2025. Interest payments are recognized in interest income. We evaluate the note for impairment on a quarterly basis. We determine the note receivable to be impaired if we are uncertain of its collectability based on the contractual terms. At December 31, 2019 and 2018, there was no impairment.

Warranties

Warranties	12 Months Ended
	Dec. 31, 2019
Guarantees [Abstract]
Warranties	Warranties The Company has warranties with various terms from 18 months for parts to 25 years for certain heat exchangers. The Company has an obligation to replace parts if conditions under the warranty are met. A provision is made for estimated warranty costs at the time the related products are sold based upon the warranty period, historical trends, new products and any known identifiable warranty issues. Changes in the warranty accrual are as follows: Years Ended December 31, 2019 2018 2017 Warranty accrual: (in thousands) Balance, beginning of period $ 11,421 $ 10,483 $ 7,936 Payments made (6,816) (7,869) (8,686) Provisions 8,047 9,669 11,233 Change in estimate — (862) — Balance, end of period $ 12,652 $ 11,421 $ 10,483 Warranty expense: $ 8,047 $ 8,807 $ 11,233 The change in estimate relates to the Company’s failure rate calculation. During 2018, in reviewing claims data, the Company noted specific claims that were the result of an isolated incident and not representative of the Company’s historical performance or representative of expected future claims. As such, these claims were accounted for as a specific accrual for warranty liability and excluded from our failure rate that the Company utilizes in estimating future claims.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities At December 31, accrued liabilities were comprised of the following: December 31, 2019 2018 (in thousands) Warranty $ 12,652 $ 11,421 Due to representatives 11,538 11,024 Payroll 5,058 4,182 Profit sharing 1,721 1,255 Workers' compensation 522 567 Medical self-insurance 707 1,207 Customer prepayments 4,627 2,367 Donations 354 150 Employee vacation time 3,804 3,173 Other 3,286 1,529 Total $ 44,269 $ 36,875

Revolving Credit Facility

Revolving Credit Facility	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Revolving Credit Facility	Revolving Credit Facility Our revolving credit facility (“BOK Revolver”), as amended, provides for maximum borrowings of $30.0 million which is provided by BOKF, NA dba Bank of Oklahoma (“Bank of Oklahoma”). Under the line of credit, there was one standby letter of credit totaling $1.7 million as of December 31, 2019. Borrowings available under the revolving credit facility at December 31, 2019, were $28.3 million. Interest on borrowings is payable monthly at LIBOR plus 2.0%. No fees are associated with the unused portion of the committed amount. As of December 31, 2019 and 2018, we had no balance outstanding under our revolving credit facility. The revolving credit facility expires on July 26, 2021. At December 31, 2019 and 2018, the weighted average interest rate of our revolving credit facility was 4.3% and 4.2%, respectively. At December 31, 2019, we were in compliance with our financial covenants. These covenants require that we meet certain parameters related to our tangible net worth and total liabilities to tangible net worth ratio. At December 31, 2019 our tangible net worth was $290.1 million, which meets the requirement of being at or above $175.0 million. Our total liabilities to tangible net worth ratio was 0.3 to 1.0, which meets the requirement of not being above 2 to 1. On October 24, 2019 we amended the BOK Revolver to allow for the occurrence of transactions associated with the New Markets Tax Credit transaction (Note 19). This amendment also removed section 8.1.4 which required our Chief Executive Officer, Norman Asbjornson, to maintain ownership of 25% of the Company. As Mr. Norman Asbjornson does not currently, and has not for several years maintained this level of ownership, a limited waiver of default was also added to the amendment.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The provision (benefit) for income taxes consists of the following: Years Ended December 31, 2019 2018 2017 (in thousands) Current $ 7,282 $ 10,530 $ 21,543 Deferred 6,038 2,641 (749) Total $ 13,320 $ 13,171 $ 20,794 The provision for income taxes differs from the amount computed by applying the statutory federal income tax rate before the provision for income taxes. The reconciliation of the federal statutory income tax rate to the effective income tax rate is as follows: Years Ended December 31, 2019 2018 2017 Federal statutory rate 21 % 21 % 35 % State income taxes, net of federal benefit 5 % 6 % 5 % Remeasurement of deferred taxes — % — % (5) % Domestic manufacturing deduction — % — % (3) % Excess tax benefits (3) % (2) % (3) % Return to provision (1) % — % — % Oklahoma amended tax returns (1) % — % — % Other (1) % (1) % (1) % 20 % 24 % 28 % The Tax Cuts and Jobs Act (the “Act”) was enacted on December 22, 2017. Major changes under the Act include the following: • Reducing the corporate rate to 21 percent • Doubling bonus depreciation to 100 percent for five years • Further limitations on executive compensation deductions • Eliminating the domestic manufacturing deduction As a result of these changes, the Company adjusted its deferred tax assets and liabilities in 2017 using the newly enacted rates for the periods when they are expected to be realized. The remeasurement in 2017 resulted in a benefit to income taxes of $3.7 million. The new bonus depreciation provisions resulted in the Company taking $3.2 million of bonus depreciation in 2017. The Company also has historically taken the domestic manufacturing deduction. The Company will no longer receive the benefit of this deduction which typically has lowered our effective tax rate by 3.0%. The Company sometimes has executive compensation that exceeds the $1.0 million limitation. Typically the limit is exceeded due to the volume of stock activity performed by the executives during the year. The limit could also be exceeded by the Chief Executive Officer receiving the maximum amount under our executive annual cash incentive bonus plan. Any compensation that exceeded this limitation in 2018 and in the future will be a permanent difference and cause an increase to our income tax provision. Upon completion of the Company's 2018 tax return in 2019, the Company recorded additional benefit due to higher than expected research and development credit of $0.6 million. Additionally in 2019, the Company determined it could take advantage of an additional 1% tax credit in Oklahoma for years in which the Company's location was deemed to be within an enterprise zone. The additional OK Credit for being in an enterprise zone, or otherwise allowable under Oklahoma law, resulted in a benefit of $1.2 million. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amount used for income tax purposes. The significant components of the Company’s deferred tax assets and liabilities are as follows: December 31, 2019 2018 (in thousands) Deferred income tax assets (liabilities): Accounts receivable and inventory reserves $ 835 $ 401 Warranty accrual 3,523 3,105 Other accruals 1,919 2,445 Share-based compensation 3,906 3,264 Donations 194 80 Other, net 2,140 851 Total deferred income tax assets 12,517 10,146 Property & equipment (27,814) (19,405) Total deferred income tax liabilities $ (27,814) $ (19,405) Net deferred income tax liabilities $ (15,297) $ (9,259) We file income tax returns in the U.S., state and foreign income tax returns jurisdictions. We are subject to U.S. examinations for tax years 2016 to present, and to non-U.S. income tax examinations for the tax years 2015 to present. In addition, we are subject to state and local income tax examinations for tax years 2015 to present. The Company continues to evaluate its need to file returns in various state jurisdictions. Any interest or penalties would be recognized as a component of income tax expense.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	Share-Based Compensation On May 22, 2007, our stockholders adopted a Long-Term Incentive Plan (“LTIP”) which provided an additional 3.3 million shares that could be granted in the form of stock options, stock appreciation rights, restricted stock awards, performance units and performance awards, in addition to the shares from the previous plan, the 1992 Plan. Since inception of the LTIP, non-qualified stock options and restricted stock awards have been granted with a five On May 24, 2016, our stockholders adopted the 2016 Long-Term Incentive Plan (“2016 Plan”) which provides for approximately 6.4 million shares, comprised of 3.4 million new shares provided for under the 2016 Plan, approximately 0.4 million shares that were available for issuance under the previous LTIP that are now authorized for issuance under the 2016 Plan, and an additional 2.6 million shares that were approved by the stockholders on May 15, 2018. Under the 2016 Plan, shares can be granted in the form of stock options, stock appreciation rights, restricted stock awards, performance awards, dividend equivalent rights, and other awards. Under the 2016 Plan, the exercise price of shares granted may not be less than 100% of the fair market value at the date of the grant. The 2016 Plan is administered by the Compensation Committee of the Board of Directors or such other committee of the Board of Directors as is designated by the Board of Directors (the “Committee”). Membership on the Committee is limited to independent directors. The Committee may delegate certain duties to one or more officers of the Company as provided in the 2016 Plan. The Committee determines the persons to whom awards are to be made, determines the type, size and terms of awards, interprets the 2016 Plan, establishes and revises rules and regulations relating to the 2016 Plan and makes any other determinations that it believes necessary for the administration of the 2016 Plan. The following weighted average assumptions were used to determine the fair value of the stock options granted on the original grant date for expense recognition purposes for options granted during December 31, 2019, 2018, and 2017 using a Black Scholes-Merton Model: 2019 2018 2017 Director and Officers: Expected dividend yield $ 0.32 $ 0.26 $ 0.26 Expected volatility 29.54 % 29.73 % 30.81 % Risk-free interest rate 2.40 % 2.20 % 1.90 % Expected life (in years) 5.00 5.00 5.00 Employees: Expected dividend yield $ 0.32 $ 0.26 $ 0.26 Expected volatility 29.54 % 29.82 % 30.67 % Risk-free interest rate 2.38 % 2.51 % 1.89 % Expected life (in years) 5.00 5.00 5.00 The expected term of the options is based on evaluations of historical and expected future employee exercise behavior. The risk-free interest rate is based on the U.S. Treasury rates at the date of grant with maturity dates approximately equal to the expected life at the grant date. Volatility is based on historical volatility of our stock over time periods equal to the expected life at grant date. The following is a summary of stock options vested and exercisable as of December 31, 2019: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $7.18 - 34.10 451,077 5.44 $ 23.47 $ 11,702 $34.15 - 40.87 86,122 7.82 36.33 1,126 $41.37 - 50.68 1,750 1.81 41.59 14 Total 538,949 5.81 $ 25.58 $ 12,842 The following is a summary of stock options vested and exercisable as of December 31, 2018: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $5.67 - 32.80 456,223 5.72 $ 20.25 $ 6,757 $32.85 - 34.10 42,552 7.47 33.95 47 $34.15 - 42.94 17,202 8.30 35.19 7 Total 515,977 5.95 $ 21.88 $ 6,811 The following is a summary of stock options vested and exercisable as of December 31, 2017: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $4.54 - 22.76 424,130 4.36 $ 12.41 $ 10,303 $23.57 - 32.85 107,456 8.31 30.10 709 $32.90 - 37.30 25,725 9.19 34.07 68 Total 557,311 5.35 $ 16.82 $ 11,080 A summary of option activity under the plans is as follows: Weighted Average Exercise Options Shares Price Outstanding at December 31, 2018 2,445,849 $ 30.77 Granted 1,975,820 41.50 Exercised (444,389) 28.40 Forfeited or Expired (350,233) 36.78 Outstanding at December 31, 2019 3,627,047 $ 36.32 Exercisable at December 31, 2019 538,949 $ 25.58 The total pre-tax compensation cost related to unvested stock options not yet recognized as of December 31, 2019 is $19.4 million and is expected to be recognized over a weighted-average period of 3.58 years. The total intrinsic value of options exercised during the years ended December 31, 2019, 2018, and 2017 was $8.1 million, $5.4 million, and $4.5 million, respectively. The cash received from options exercised during the year ended December 31, 2019, 2018, and 2017 was $12.6 million, $5.0 million, and $2.3 million, respectively. The impact of these cash receipts is included in financing activities in the accompanying Consolidated Statements of Cash Flows. A summary of the unvested restricted stock awards is as follows: Weighted Average Grant date Restricted stock Shares Fair Value Unvested at December 31, 2018 292,450 $ 28.54 Granted 113,018 40.98 Vested (122,278) 26.38 Forfeited (15,706) 34.71 Unvested at December 31, 2019 267,484 $ 34.42 At December 31, 2019, unrecognized compensation cost related to unvested restricted stock awards was approximately $4.6 million which is expected to be recognized over a weighted average period of 2.64 years. A summary of share-based compensation is as follows for the years ended December 31, 2019, 2018, and 2017: 2019 2018 2017 Grant date fair value of awards during the period: (in thousands) Options $ 20,442 $ 12,932 $ 3,699 Restricted stock 4,631 3,609 4,217 Total $ 25,073 $ 16,541 $ 7,916 2019 2018 2017 Share-based compensation expense: (in thousands) Options $ 9,145 $ 5,344 $ 3,095 Restricted stock 2,654 2,518 3,218 Total $ 11,799 $ 7,862 $ 6,313 2019 2018 2017 Income tax benefit related to share-based compensation: (in thousands) Options $ 1,197 $ 980 $ 1,413 Restricted stock 575 353 1,051 Total $ 1,772 $ 1,333 $ 2,464

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Defined Contribution Plan - 401(k ) We sponsor a defined contribution plan (the “Plan”). Eligible employees may make contributions in accordance with the Plan and IRS guidelines. In addition to the traditional 401(k), eligible employees are given the option of making an after-tax contribution to a Roth 401(k) or a combination of both. The Plan provides for automatic enrollment and for an automatic increase to the deferral percentage at January 1st of each year and each year thereafter. Eligible employees are automatically enrolled in the Plan at a 6% deferral rate and currently contributing employees deferral rates will be increased to 6% unless their current rate is above 6% or the employee elects to decline the automatic enrollment or increase. Administrative expenses are paid for by Plan participants. The Company paid no administrative expenses for the years ended 2019, 2018 and 2017. The Company matches 175% up to 6% of employee contributions of eligible compensation. Additionally, Plan participant forfeitures are used to reduce the cost of the Company contributions. Years Ended December 31, 2019 2018 2017 (in thousands) Contributions made to the defined contribution plan $ 7.0 $ 8.1 $ 6.1 Profit Sharing Bonus Plan We maintain a discretionary profit sharing bonus plan under which approximately 10% of pre-tax profit is paid to eligible employees on a quarterly basis in order to reward employee productivity. Eligible employees are regular full-time employees who are actively employed and working on the first and last days of the calendar quarter and who were employed full-time for at least three full months prior to the beginning of the calendar quarter, excluding the Company's senior leadership team. Years Ended December 31, 2019 2018 2017 (in thousands) Profit sharing bonus plan expense $ 7.4 $ 6.2 $ 8.4 Employee Medical Plan We self-insure for our employee's health insurance. Eligible employees are regular full-time employees who are actively employed and working. Participants are expected to pay a portion of the premium costs for coverage of the benefits provided under the Plan. We estimate our self-insurance liabilities using an analysis provided by our claims administrator and our historical claims experience. In addition, the Company matches 175% of a participating employee's allowed contributions to a qualified health saving account to assist employees with our heath insurance plan deductibles. Years Ended December 31, 2019 2018 2017 (in thousands) Medical claim payments $ 5.9 $ 5.9 $ 4.8 Heath saving account payments 3.3 2.9 2.5

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Shareholders' Equity	Stockholders’ Equity Stock Repurchase The Board has authorized three stock repurchase programs for the Company. The Company may purchase shares on the open market from time to time, up to a total of 5.7 million shares. The Board must authorize the timing and amount of these purchases and all repurchases are in accordance with the rules and regulations of the SEC allowing the Company to repurchase shares from the open market. Our open market repurchase programs are as follows: Agreement Execution Date Authorized Repurchase $ Expiration Date June 2, 2016 $25 million April 15, 2017 May 16, 2018 $15 million March 1, 2019 March 5, 2019 $20 million March 4, 2020 The Company also has a stock repurchase arrangement by which employee-participants in our 401(k) savings and investment plan are entitled to have shares in AAON, Inc. stock in their accounts sold to the Company. The maximum number of shares to be repurchased is contingent upon the number of shares sold by employee-participants. Lastly, the Company repurchases shares of AAON, Inc. stock from certain of its directors and employees for payment of statutory tax withholdings on stock transactions. All other repurchases from directors or employees are contingent upon Board approval. All repurchases are done at current market prices. Our repurchase activity is as follows: 2019 2018 2017 (in thousands, except share and per share data) Program Shares Total $ $ per share Shares Total $ $ per share Shares Total $ $ per share Open market 5,799 $ 200 $ 34.46 252,272 $ 8,374 $ 33.19 8,676 $ 284 $ 32.69 401(k) 419,963 19,386 46.16 497,753 18,472 37.11 467,580 16,336 34.94 Directors & employees 28,668 1,207 42.11 33,751 1,097 32.49 45,878 1,614 35.19 Total 454,430 $ 20,793 $ 45.76 783,776 $ 27,943 $ 35.65 522,134 $ 18,234 $ 34.92 Inception to Date (in thousands, except share and per share data) Program Shares Total $ $ per share Open market 4,101,566 $ 69,806 $ 17.02 401(k) 7,467,739 119,927 16.06 Directors & employees 1,981,929 19,582 9.88 Total 13,551,234 $ 209,315 $ 15.45 Dividends At the discretion of the Board of Directors, we pay semi-annual cash dividends. Board approval is required to determine the date of declaration and amount for each semi-annual dividend payment. Our recent dividends are as follows: Declaration Date Record Date Payment Date Dividend per Share May 16, 2017 June 9, 2017 July 7, 2017 $0.13 November 7, 2017 November 30, 2017 December 21, 2017 $0.13 May 18, 2018 June 8, 2018 July 6, 2018 $0.16 November 8, 2018 November 29, 2018 December 20, 2018 $0.16 May 20, 2019 June 3, 2019 July 1, 2019 $0.16 November 6, 2019 November 27, 2019 December 18, 2019 $0.16 We paid cash dividends of $16.6 million, $16.7 million, and $13.7 million in 2019, 2018, and 2017, respectively.

New Markets Tax Credit

New Markets Tax Credit	12 Months Ended
	Dec. 31, 2019
New Market Tax Credit [Abstract]
New Markets Tax Credit	New Markets Tax Credit On October 24, 2019, the Company entered into a transaction with a subsidiary of an unrelated third-party financial institution (the “Investor”) and a certified Community Development Entity under a qualified New Markets Tax Credit (“NMTC”) program pursuant to Section 45D of the Internal Revenue Code of 1986, as amended, related to an investment in plant and equipment to facilitate the expansion of our Longview, Texas manufacturing operations (the “Project”). In connection with the NMTC transaction, the Company received a $23.0 million NMTC allocation for the Project and secured low interest financing and the potential for future debt forgiveness related to the Project. Upon closing of the NMTC transaction, the Company provided an aggregate of approximately $15.9 million to the Investor, in the form of a loan receivable, with a term of twenty-five years, bearing an interest rate of 1.0%. This $15.9 million in proceeds plus capital contributed from the Investor was used to make an aggregate $22.5 million loan to a subsidiary of the Company. This financing arrangement is secured by equipment at the Company's Longview, Texas facilities and a guarantee from the Company, including an unconditional guarantee of NMTCs. This transaction also includes a put/call feature that either of which can be exercised at the end of the seven-year compliance period. The Investor may exercise its put option or the Company can exercise the call, both of which could serve to trigger forgiveness of a portion of the debt. The value attributable to the put/call is nominal. The Investor's interest of $6.3 million is recorded in New market tax credit obligation on the consolidated balance sheet. The Company incurred approximately $0.3 million of debt issuance costs related to the above transactions, which are being amortized over the life of the transaction. The Investor is subject to 100 percent recapture of the NMTC it receives for a period of seven years, as provided in the Internal Revenue Code and applicable U.S. Treasury regulations in the event that the financing facility of the Borrower under the transaction (AAON Coil Products, Inc.) becomes ineligible for NMTC treatment per the Internal Revenue Code requirements. The Company is required to be in compliance with various regulations and contractual provisions that apply to the NMTC arrangement. Noncompliance with applicable requirements could result in the Investor’s projected tax benefits not being realized and, therefore, require the Company to indemnify the Investor for any loss or recapture of the NMTC related to the financing until such time as the recapture provisions have expired under the applicable statute of limitations. The Company does not anticipate any credit recapture will be required in connection with this financing arrangement. The Investor and its majority owned community development entity are considered VIEs and the Company is the primary beneficiary of the VIEs. This conclusion was reached based on the following: • the ongoing activities of the VIEs--collecting and remitting interest and fees and NMTC compliance--were all considered in the initial design and are not expected to significantly affect performance throughout the life of the VIE; • contractual arrangements obligate the Company to comply with NMTC rules and regulations and provide various other guarantees to the Investor and community development entity; • the Investor lacks a material interest in the underling economics of the project; and • the Company is obligated to absorb losses of the VIEs. Because the Company is the primary beneficiary of the VIEs, they have been included in the consolidated financial statements. There are no other assets, liabilities or transaction in these VIEs outside of the financing transactions executed as part of the NMTC arrangement.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are subject to various claims and legal actions that arise in the ordinary course of business. We closely monitor these claims and legal actions and frequently consult with our legal counsel to determine whether they may, when resolved, have a material adverse effect on our financial position, results of operations or cash flows and we accrue and/or disclose loss contingencies as appropriate. We have concluded that the likelihood is remote that the ultimate resolution of any pending litigation or claims will be material or have a material adverse effect on the Company’s business, financial position, results of operations or cash flows. We are occasionally party to short-term, cancellable and occasionally non-cancellable, fixed price contracts with major suppliers for the purchase of raw material and component parts. We expect to receive delivery of raw materials for use in our manufacturing operations. These contracts are not accounted for as derivative instruments because they meet the normal purchase and normal sales exemption. At December 31, 2019, we had one material contractual purchase obligation for approximately $2.5 million that expires in December 2020.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic net income per share is calculated by dividing net income by the weighted average number of shares of common stock outstanding during the period. Diluted net income per share assumes the conversion of all potentially dilutive securities and is calculated by dividing net income by the sum of the weighted average number of shares of common stock outstanding plus all potentially dilutive securities. Dilutive common shares consist primarily of stock options and restricted stock awards. The following table sets forth the computation of basic and diluted earnings per share: 2019 2018 2017 Numerator: (in thousands, except share and per share data) Net income $ 53,711 $ 42,329 $ 53,830 Denominator: Basic weighted average shares 52,079,865 52,284,616 52,572,496 Effect of dilutive stock options and restricted stock 555,550 383,323 506,238 Diluted weighted average shares 52,635,415 52,667,939 53,078,734 Earnings per share: Basic $ 1.03 $ 0.81 $ 1.02 Dilutive $ 1.02 $ 0.80 $ 1.01 Anti-dilutive shares: Shares 1,868,087 1,920,313 785,825

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Parties	Related Parties The Company purchases some supplies from an entity controlled by the Company’s CEO. The Company sometimes makes sales to the CEO for parts. Additionally, the Company sells units to an entity owned by a member of the President's immediate family. This entity is also one of the Company’s Representatives and as such, the Company makes payments to the entity for third party products. Following is a summary of transactions and balances with affiliates: Years Ended December 31, 2019 2018 2017 (in thousands) Sales to affiliates $ 886 $ 1,442 $ 1,579 Payments to affiliates 332 342 432 December 31, 2019 2018 (in thousands) Due from affiliates $ 22 $ 79 Due to affiliates 2 —

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Subsequent to December 31, 2019 and through February 24, 2020, the Company repurchased 11,144 shares for $0.6 million from employees for payment of statutory tax withholdings on stock transactions and 73,780 shares for $3.9 million from our 401(k) savings and investment plan.

Quarterly Results (Unaudited) (

Quarterly Results (Unaudited) (As Corrected)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results (Unaudited)	Quarterly Results (Unaudited) (As Corrected) The following is a summary of the quarterly results of operations for the years ended December 31, 2019 and 2018: Quarter First Second Third Fourth (in thousands, except per share data) 2019 Net sales $ 113,822 $ 119,437 $ 113,500 $ 122,574 Gross profit 25,430 30,204 27,410 36,381 Net income 8,757 13,391 14,290 17,273 Earnings per share: Basic $ 0.17 $ 0.26 $ 0.27 $ 0.33 Diluted $ 0.17 $ 0.26 $ 0.26 $ 0.33 2018 Net sales $ 99,082 $ 109,588 $ 112,937 $ 112,340 Gross profit 15,196 27,661 32,830 27,846 Net income 3,154 11,697 14,514 12,964 Earnings per share: Basic $ 0.06 $ 0.22 $ 0.28 $ 0.25 Diluted $ 0.06 $ 0.22 $ 0.27 $ 0.25 The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended March 31, 2019 and 2018. Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 113,822 $ — $ 113,822 $ 99,082 $ — $ 99,082 Cost of sales 88,029 363 (a) 88,392 83,692 194 (a) 83,886 Gross profit 25,793 (363) 25,430 15,390 (194) 15,196 Selling, general and administrative expenses 11,001 2,676 (b) 13,677 10,219 1,432 (b) 11,651 Loss (gain) on disposal of assets 284 — 284 (7) — (7) Income from operations 14,508 (3,039) 11,469 5,178 (1,626) 3,552 Interest income, net 9 — 9 68 — 68 Other (expense) income, net (26) — (26) (6) — (6) Income before taxes 14,491 (3,039) 11,452 5,240 (1,626) 3,614 Income tax provision 3,589 (894) (c) 2,695 980 (520) (c) 460 Net income $ 10,902 $ (2,145) $ 8,757 $ 4,260 $ (1,106) $ 3,154 Earnings per share: Basic $ 0.21 $ (0.04) $ 0.17 $ 0.08 $ (0.02) $ 0.06 Diluted $ 0.21 $ (0.04) $ 0.17 $ 0.08 $ (0.02) $ 0.06 Weighted average shares outstanding: Basic 51,992,150 — 51,992,150 52,433,902 — 52,433,902 Diluted 52,369,660 — 52,369,660 52,910,223 — 52,910,223 Balance Sheet Data (at end of period): Current assets $ 146,798 $ (287) (c) $ 146,511 $ 154,687 $ (237) (c) $ 154,450 Total assets 319,525 (287) (c) 319,238 306,945 (237) (c) 306,708 Current liabilities 44,000 (918) (d) 43,082 57,292 (711) (d) 56,581 Deferred income taxes 12,713 (2,545) (c) 10,168 8,397 (1,926) (c) 6,471 Other long-term liabilities 3,442 — 3,442 1,645 — 1,645 Total stockholders' equity $ 259,370 $ 3,176 (e) $ 262,546 $ 239,611 $ 2,400 (e) $ 242,011 (a) The share-based compensation correction to cost of sales for the quarters ended March 31, 2019 and 2018 was approximately $0.4 million and $0.2 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended March 31, 2019 and 2018 was approximately $3.0 million and $1.6 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.4 million and $0.2 million for the quarters ended March 31, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation correction. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended June 30, 2019 and 2018. Three Months Ended June 30, 2019 Three Months Ended June 30, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 119,437 $ — $ 119,437 $ 109,588 $ — $ 109,588 Cost of sales 89,262 (29) (a) 89,233 82,003 (76) (a) 81,927 Gross profit 30,175 29 30,204 27,585 76 27,661 Selling, general and administrative expenses 13,481 (569) (b) 12,912 13,086 67 (b) 13,153 Loss (gain) on disposal of assets 6 — 6 (4) — (4) Income from operations 16,688 598 17,286 14,503 9 14,512 Interest income, net 31 — 31 67 — 67 Other (expense) income, net 17 — 17 12 — 12 Income before taxes 16,736 598 17,334 14,582 9 14,591 Income tax provision 3,775 168 (c) 3,943 2,891 3 (c) 2,894 Net income $ 12,961 $ 430 $ 13,391 $ 11,691 $ 6 $ 11,697 Earnings per share: Basic $ 0.25 $ 0.01 $ 0.26 $ 0.22 $ — $ 0.22 Diluted $ 0.25 $ 0.01 $ 0.26 $ 0.22 $ — $ 0.22 Cash dividends declared per common share: $ 0.16 $ — $ 0.16 $ 0.16 $ — $ 0.16 Weighted average shares outstanding: Basic 52,120,272 — 52,120,272 52,383,842 — 52,383,842 Diluted 52,474,199 — 52,474,199 52,717,787 — 52,717,787 Balance Sheet Data (at end of period): Current assets $ 168,630 $ (270) (c) $ 168,360 $ 154,665 $ (237) (c) $ 154,428 Total assets 342,251 (270) (c) 341,981 320,271 (237) (c) 320,034 Current liabilities 58,953 (851) (d) 58,102 71,673 (711) (d) 70,962 Deferred income taxes 14,938 (2,361) (c) 12,577 8,415 (1,922) (c) 6,493 Other long-term liabilities 3,791 — 3,791 1,746 — 1,746 Total stockholders' equity $ 264,569 $ 2,942 (e) $ 267,511 $ 238,437 $ 2,396 (e) $ 240,833 (a) The share-based compensation correction to cost of sales for the quarters ended June 30, 2019 and 2018 was approximately $0.1 million and $0.1 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended June 30, 2019 and 2018 was approximately $0.6 million and $0.1 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the quarters ended June 30, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation correction. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended September 30, 2019 and 2018. Three Months Ended September 30, 2019 Three Months Ended September 30, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 113,500 $ — $ 113,500 $ 112,937 $ — $ 112,937 Cost of sales 86,115 (25) (a) 86,090 80,174 (67) (a) 80,107 Gross profit 27,385 25 27,410 32,763 67 32,830 Selling, general and administrative expenses 12,994 (620) (b) 12,374 13,190 (523) (b) 12,667 Loss (gain) on disposal of assets 6 — 6 2 — 2 Income from operations 14,385 645 15,030 19,571 590 20,161 Interest income, net 9 — 9 36 — 36 Other (expense) income, net (7) — (7) 5 — 5 Income before taxes 14,387 645 15,032 19,612 590 20,202 Income tax provision 560 182 (c) 742 5,527 161 (c) 5,688 Net income $ 13,827 $ 463 $ 14,290 $ 14,085 $ 429 $ 14,514 Earnings per share: Basic $ 0.27 $ — $ 0.27 $ 0.27 $ 0.01 $ 0.28 Diluted $ 0.26 $ — $ 0.26 $ 0.27 $ — $ 0.27 Weighted average shares outstanding: Basic 52,111,444 — 52,111,444 52,238,796 — 52,238,796 Diluted 52,722,127 — 52,722,127 52,627,541 — 52,627,541 Balance Sheet Data (at end of period): Current assets $ 170,536 $ (252) (c) $ 170,284 $ 144,696 $ (220) (c) $ 144,476 Total Assets 352,152 (252) (c) 351,900 314,024 (220) (c) 313,804 Current liabilities 53,882 (779) (d) 53,103 53,716 (645) (d) 53,071 Deferred income taxes 15,034 (2,161) (c) 12,873 8,841 (1,744) (c) 7,097 Other long-term liabilities 3,669 — 3,669 1,838 — 1,838 Total stockholders' equity $ 279,567 $ 2,688 (e) $ 282,255 $ 249,629 $ 2,169 (e) $ 251,798 (a) The share-based compensation correction to cost of sales for the quarters ended September 30, 2019 and 2018 was approximately $0.1 million and $0.1 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended September 30, 2019 and 2018 was approximately $0.7 million and $0.6 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the quarters ended September 30, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following table reconciles our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended December 31, 2018. Three Months Ended December 31, 2018 Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 112,340 $ — $ 112,340 Cost of sales 84,545 (51) (a) 84,494 Gross profit 27,795 51 27,846 Selling, general and administrative expenses 11,260 (537) (b) 10,723 Loss (gain) on disposal of assets (3) — (3) Income from operations 16,538 588 17,126 Interest income, net 25 — 25 Other (expense) income, net (58) — (58) Income before taxes 16,505 588 17,093 Income tax provision 3,969 160 (c) 4,129 Net income $ 12,536 $ 428 $ 12,964 Earnings per share: Basic $ 0.24 $ 0.01 $ 0.25 Diluted $ 0.24 $ 0.01 $ 0.25 Cash dividends declared per common share: $ 0.16 $ — $ 0.16 Weighted average shares outstanding: Basic 52,086,247 — 52,086,247 Diluted 52,420,529 — 52,420,529 Balance Sheet Data (at end of period): Current assets $ 140,861 $ (203) (c) $ 140,658 Total Assets 308,197 (203) (c) 307,994 Current liabilities 48,071 (580) (d) 47,491 Deferred income taxes 10,826 (1,567) (c) 9,259 Other long-term liabilities 1,801 — 1,801 Total stockholders' equity $ 247,499 $ 1,944 (e) $ 249,443 (a) The share-based compensation correction for cost of sales for the quarter ended December 31, 2018 was approximately $0.1 million. (b) The share-based compensation correction to selling, general and administrative expenses for the quarter ended December 31, 2018 was approximately $0.6 million. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million for the quarter ended December 31, 2018. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2018.

Segments

Segments	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segments	Segments The following table summarizes certain financial data related to our segments. Transactions between segments are recorded based on prices negotiated between the segments. Sales of units represents the selling price of our units plus freight and other miscellaneous charges less any returns and allowances. Parts includes sales of purchased and fabricated parts including our coils along with the related freight and less any returns and allowances. The “Other” category in the table below includes certain sales cost and expenses that are not allocated to the reportable segments. Asset information by segment is not easily identifiable or reviewed by the chief operating decision maker. As such, this information is not included below. Years Ended December 31, 2019 2018 2017 (in thousands) Sales Units $ 434,283 $ 406,331 $ 384,853 Parts - External 35,424 28,456 22,050 Parts - Inter-segment 28,053 29,385 29,293 Other (374) (840) (1,671) Eliminations (28,053) (29,385) (29,293) Net sales $ 469,333 $ 433,947 $ 405,232 Gross Profit Units $ 121,878 $ 108,214 $ 128,647 Parts - External 17,301 13,215 9,555 Parts - Inter-segment 985 865 426 Other (19,754) (17,896) (14,551) Eliminations (985) (865) (426) Gross profit $ 119,425 $ 103,533 $ 123,651

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation These financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated. Our financial statements consolidate all of our affiliated entities in which we have a controlling financial interest. Because we hold certain rights that give us the power to direct the activities of two variable interest entities ("VIEs") (Note 18) that most significantly impact the VIEs economic performance, combined with a variable interest that gives us the right to receive potentially significant benefits or the obligation to absorb potentially significant losses, we have a controlling financial interest in those VIEs.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid temporary investments with original maturity dates of three months or less to be cash equivalents. Cash and cash equivalents consist of bank deposits and highly liquid, interest-bearing money market funds. The Company’s cash and cash equivalents are held in a few financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected.
Restricted Cash	Restricted Cash Restricted cash held at December 31, 2019 consist of bank deposits and highly liquid, interest-bearing money market funds held for the purpose of the Company's qualified New Markets Tax Credit program (Note 19) to benefit an investment in plant and equipment to facilitate the expansion of our Longview, Texas manufacturing operations. The Company’s restricted cash is held in a financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected.
Investments	Certificates of Deposit We held no certificates of deposit at December 31, 2019 and 2018. Investments Held to Maturity
Accounts and Note Receivable	Accounts and Note Receivable Accounts and note receivable are stated at amounts due from customers, net of an allowance for doubtful accounts. We generally do not require that our customers provide collateral. The Company determines its allowance for doubtful accounts by considering a number of factors, including the credit risk of specific customers, the customer’s ability to pay current obligations, historical trends, economic and market conditions and the age of the receivable. Accounts are considered past due when the balance has been outstanding for ninety days past negotiated credit terms. Past due accounts are generally written-off against the allowance for doubtful accounts only after all collection attempts have been exhausted.
Concentration of Credit Risk	Concentration of Credit Risk Our customers are concentrated primarily in the domestic commercial and industrial new construction and replacement markets. To date, our sales have been primarily to the domestic market, with foreign sales accounting for approximately 3%, 3% and 4% of revenues for the years ended December 31, 2019, 2018, and 2017, respectively. One customer, Texas AirSystems, accounted for approximately 10% of our sales during 2019, 2018 and 2017. No other customer accounted for more than 5% of our sales during 2019, 2018 and 2017. One customer, Texas AirSystems, accounted for approximately 10% of our accounts receivable balance at December 31, 2019. No other customer accounted for 5% or more of our accounts receivable balance at December 31, 2019 and 2018.
Inventories	Inventories Inventories are valued at the lower of cost or net realizable value using the first-in, first-out (“FIFO”) method. Cost in inventory includes purchased parts and materials, direct labor and applied manufacturing overhead. We establish an allowance for excess and obsolete inventories based on product line changes, the feasibility of substituting parts and the need for supply and replacement parts.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment, including significant improvements, are recorded at cost, net of accumulated depreciation. Repairs and maintenance and any gains or losses on disposition are included in operations. Depreciation is computed using the straight-line method over the following estimated useful lives: Buildings 3 - 40 years Machinery and equipment 3 - 15 years Furniture and fixtures 3 - 7 years
Business Combinations	Business Combinations We record the assets acquired and liabilities assumed in a business combination at their acquisition date fair values.
Fair Value of Financial Instruments	The carrying amounts of cash and cash equivalents, receivables, accounts payable and accrued liabilities approximate fair value because of the short-term maturity of the items. The carrying amount of the Company’s revolving line of credit, and other payables, approximate their fair values either due to their short term nature, the variable rates associated with the debt or based on current rates offered to the Company for debt with similar characteristics.
Fair Value Measurements	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Fair value is based upon assumptions that market participants would use when pricing an asset or liability. We use the following fair value hierarchy, which prioritizes valuation technique inputs used to measure fair value into three broad levels: • Level 1: Quoted prices in active markets for identical assets and liabilities that we have the ability to access at the measurement date. • Level 2: Inputs (other than quoted prices included within Level 1) that are either directly or indirectly observable for the asset or liability, including (i) quoted prices for similar assets or liabilities in active markets, (ii) quoted prices for identical or similar assets or liabilities in inactive markets, (iii) inputs other than quoted prices that are observable for the asset or liability, and (iv) inputs that are derived from observable market data by correlation or other means. • Level 3: Unobservable inputs for the asset or liability including situations where there is little, if any, market activity for the asset or liability. Items categorized in Level 3 include the estimated business combination fair values of property, plant and equipment, intangible assets and goodwill.
Intangible Assets	Intangible Assets Our intangible assets include various trademarks, service marks and technical knowledge acquired in our February 2018 business combination (Note
Goodwill	Goodwill Goodwill represents the excess of the consideration paid for the acquired businesses over the fair value of the individual assets acquired, net of liabilities assumed. Goodwill at December 31, 2019 is deductible for income tax purposes. Goodwill is not amortized, but instead is evaluated for impairment at least annually. We perform our annual assessment of impairment during the fourth quarter of our fiscal year, and more frequently if circumstances warrant. To perform this assessment, we first consider qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit exceeds its carrying amount. If we conclude that it is more likely than not that the fair value of a reporting unit does not exceed its carrying amount, we calculate the fair value for the reporting unit and compare the amount to its carrying amount, including goodwill. If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not considered impaired. If the carrying amount of a reporting unit exceeds its fair value, goodwill is considered to be impaired and the goodwill balance is reduced by the difference between the fair value and carrying amount of the reporting unit. We performed a qualitative assessment as of December 31, 2019 to determine whether it was more likely than not that the fair value of the reporting unit was greater than the carrying value of the reporting unit. Based on these qualitative assessments, we determined that the fair value of the reporting unit was more likely than not greater than the carrying value of the reporting unit. Estimates and assumptions used to perform the impairment evaluation are inherently uncertain and can significantly affect the outcome of the analysis. The estimates and assumptions we use in the annual goodwill impairment assessment included market participant considerations and future forecasted operating results. Changes in operating results and other assumptions could materially affect these estimates.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We review long-lived assets for possible impairment when events or changes in circumstances indicate, in management’s judgment, that the carrying amount of an asset may not be recoverable. Recoverability is measured by a comparison of the carrying amount of an asset or asset group to its estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the undiscounted cash flows are less than the carrying amount of the asset or asset group, an impairment loss is recognized for the amount by which the carrying amount of the asset or asset group exceeds its fair value.
Research and Development	Research and Development The costs associated with research and development for the purpose of developing and improving new products are expensed as incurred. For the years ended December 31, 2019, 2018, and 2017 research and development costs amounted to approximately $14.8 million, $13.5 million, and $13.0 million, respectively.
Advertising	Advertising Advertising costs are expensed as incurred. Advertising expense for the years ended December 31, 2019, 2018, and 2017 was approximately $0.8 million, $0.8 million, and $1.7 million, respectively.
Revenue Recognition	Shipping and Handling We incur shipping and handling costs in the distribution of products sold that are recorded in cost of sales. Shipping charges that are billed to the customer are recorded in revenues and as an expense in cost of sales. For the years ended December 31, 2019, 2018, and 2017 shipping and handling fees amounted to approximately $14.4 million, $12.6 million, and $11.4 million, respectively. Revenue Recognition On January 1, 2018, we adopted the new accounting standard FASB ASC Topic 606, Revenue from Contracts with Customers , and all the related amendments to all contracts using the retrospective method. The impact at adoption was not material to the consolidated financial statements. The new accounting policy provides results substantially consistent with prior revenue recognition policies. The Company recognizes revenue when it satisfies the performance obligation in its contracts. Most of the Company’s products are highly customized, cannot be resold to other customers and the cost of rework to be resold is not economical. The Company has a formal cancellation policy and generally does not accept returns on these units. As a result, many of the Company’s products do not have an alternative use and therefore, for these products we recognize revenue over the time it takes to produce the unit. For all other products that are part sales or standardized units, we satisfy the performance obligation when the control is passed to the customer, generally at time of shipment. Final sales prices are fixed based on purchase orders. Sales allowances and customer incentives are treated as reductions to sales and are provided for based on historical experiences and current estimates. Sales of our products are moderately seasonal with the peak period being July - November of each year. In addition, the Company presents revenues net of sales tax and net of certain payments to our independent manufacturer representatives (“Representatives”). Representatives are national companies that are in the business of providing HVAC units and other related products and services to customers. The end user customer orders a bundled group of products and services from the Representative and expects the Representative to fulfill the order. Only after the specifications are agreed to by the Representative and the customer, and the decision is made to use an AAON HVAC unit, will we receive notice of the order. We establish the amount we must receive for our HVAC unit (“minimum sales price”), but do not control the total order price that is negotiated by the Representative with the end user customer. We are responsible for billings and collections resulting from all sales transactions, including those initiated by our Representatives. The Representatives submit the total order price to us for invoicing and collection. The total order price includes our minimum sales price and an additional amount which may include both the Representatives’ fee and amounts due for additional products and services required by the customer. These additional products and services may include controls purchased from another manufacturer to operate the unit, start-up services, and curbs for supporting the unit (“Third Party Products”). All are associated with the purchase of a HVAC unit but may be provided by the Representative or another third party. The Company is under no obligation related to Third Party Products. The Representatives’ fee and Third Party Products amounts (“Due to Representatives”) are paid only after all amounts associated with the order are collected from the customer. The amount of payments to our representatives was $46.1 million, $47.8 million, and $51.8 million for each of the years ended December 31, 2019, 2018, and 2017, respectively. The Company also sells extended warranties on parts for various lengths of time ranging from six
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the book carrying amounts and the tax basis of assets and liabilities. Excess tax benefits and deficiencies are reported as an income tax benefit or expense on the statement of income and are treated as discrete items to the income tax provision in the reporting period in which they occur. We establish accruals for unrecognized tax positions when it is more likely than not that our tax return positions may not be fully sustained. The Company records a valuation allowance for deferred tax assets when, in the opinion of management, it is more likely than not that deferred tax assets will not be realized.
Share-Based Compensation	Share-Based Compensation The Company recognizes expense for its share-based compensation based on the fair value of the awards that are granted. The Company’s share-based compensation plans provide for the granting of stock options and restricted stock. The fair values of stock options are estimated at the date of grant using the Black-Scholes-Merton option valuation model. The use of the Black-Scholes-Merton option valuation model requires the input of subjective assumptions. The fair value of restricted stock awards is based on the fair market value of AAON common stock on the respective grant dates, reduced for the present value of dividends.
Financial Derivatives	Derivative Instruments In the course of normal operations, the Company occasionally enters into contracts such as forward priced physical contracts for the purchase of raw materials that qualify for and are designated as normal purchase or normal sale contracts. Such contracts are exempted from the fair value accounting requirements and are accounted for at the time product is purchased or sold under the related contract. The Company does not engage in speculative transactions, nor does the Company hold or issue financial instruments for trading purposes.
Insurance Reserves	Insurance Reserves Under the Company’s insurance programs, coverage is obtained for significant liability limits as well as those risks required to be insured by law or contract. It is the policy of the Company to self-insure a portion of certain expected losses related primarily to workers’ compensation and medical liability. Provisions for losses expected under these programs are recorded based on the Company’s estimates of the aggregate liabilities for the claims incurred.
Product Warranties	Product Warranties A provision is made for the estimated cost of maintaining product warranties to customers at the time the product is sold based upon historical claims experience by product line. The Company records a liability and an expense for estimated future warranty claims based upon historical experience and management’s estimate of the level of future claims. Changes in the estimated amounts recognized in prior years are recorded as an adjustment to the liability and expense in the current year.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Because these estimates and assumptions require significant judgment, actual results could differ from those estimates and could have a significant impact on our results of operations, financial position and cash flows. We reevaluate our estimates and assumptions as needed, but at a minimum on a quarterly basis. The most significant estimates include, but are not limited to, the allowance for doubtful accounts, inventory reserves,
New Accounting Pronouncements	Changes to U.S. GAAP are established by the FASB in the form of accounting standards updates (“ASUs”) to the FASB’s Accounting Standards Codification. We consider the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on our consolidated financial statements and notes thereto. In December 2019, the FASB issued ASU 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes. The ASU includes simplification of accounting for income taxes for franchise taxes, step up in tax basis for goodwill as part of a business combination and interim reporting of enacted changes in tax laws. The ASU is effective for the Company beginning after December 15, 2020. We do not expect ASU 2019-12 will have a material effect on our consolidated financial statements and notes thereto. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurements: Changes to the Disclosure Requirement for Fair Value Measurements. The ASU includes additional disclosure requirements for unrealized gains and losses for Level 3 fair value measurement and significant observable inputs used to develop Level 3 fair value measurements. The ASU is effective for the Company beginning after December 15, 2019. We do not expect ASU 2018-13 will have a material effect on our consolidated financial statements and notes thereto.

Error Correction (Tables)

Error Correction (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Schedule of Error Corrections and Prior Period Adjustments	The following tables represent our corrected consolidated statements of income, statements of stockholders' equity, and statements of cash flows for the years ended December 31, 2018 and December 31, 2017, as well as our corrected consolidated balance sheet at December 31, 2018. The values as previously reported for years ended 2018 and 2017 were derived from our Annual Report on Form 10-K for the year ended December 31, 2018 filed on February 28, 2019. Consolidated Statements of Income Year Ended December 31, 2018 Year Ended December 31, 2017 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except per share data) Net sales $ 433,947 $ — $ 433,947 $ 405,232 $ — $ 405,232 Cost of sales 330,414 — (a) 330,414 281,835 (254) (a) 281,581 Gross profit 103,533 — 103,533 123,397 254 123,651 Selling, general and administrative expenses 47,755 439 (b) 48,194 49,249 122 (b) 49,371 (Gain) loss on disposal of assets (12) — (12) 45 — 45 Income from operations 55,790 (439) 55,351 74,103 132 74,235 Interest income, net 196 — 196 298 — 298 Other (expense) income, net (47) — (47) 91 — 91 Income before taxes 55,939 (439) 55,500 74,492 132 74,624 Income tax provision 13,367 (196) (c) 13,171 19,994 800 (c) 20,794 Net income $ 42,572 $ (243) $ 42,329 $ 54,498 $ (668) $ 53,830 Earnings per share: Basic $ 0.81 $ — $ 0.81 $ 1.04 $ (0.02) $ 1.02 Diluted $ 0.81 $ (0.01) $ 0.80 $ 1.03 $ (0.02) $ 1.01 Cash dividends declared per common share: $ 0.32 $ — $ 0.32 $ 0.26 $ — $ 0.26 Weighted average shares outstanding: Basic 52,284,616 — 52,284,616 52,572,496 — 52,572,496 Diluted 52,667,939 — 52,667,939 53,078,734 — 53,078,734 (a) The share-based compensation correction to cost of sales for the year ended December 31, 2017 was approximately$0.3 million. There was no correction required for the year ended December 31, 2018 for cost of sales. (b) The share-based compensation correction to selling, general and administrative expenses for the years ended December 31, 2018 and 2017 was approximately $0.5 million and $0.1 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the years ended December 31, 2018 and 2017, respectively. (c) The correction to income taxes is the tax affect of the share-based compensation correction discussed above. Consolidated Balance Sheets December 31, 2018 Previously Reported Corrections As Corrected Assets (in thousands, except share and per share data) Current assets: Cash and cash equivalents $ 1,994 $ — $ 1,994 Accounts receivable, net 54,078 — 54,078 Income tax receivable 6,104 (203) (a) 5,901 Note receivable 27 — 27 Inventories, net 77,612 — 77,612 Prepaid expenses and other 1,046 — 1,046 Total current assets 140,861 (203) 140,658 Property, plant and equipment: Land 3,114 — 3,114 Buildings 97,393 — 97,393 Machinery and equipment 212,779 — 212,779 Furniture and fixtures 16,597 — 16,597 Total property, plant and equipment 329,883 — 329,883 Less: Accumulated depreciation 166,880 — 166,880 Property, plant and equipment, net 163,003 — 163,003 Intangible assets, net 506 — 506 Goodwill 3,229 — 3,229 Note receivable, long-term 598 — 598 Total assets $ 308,197 $ (203) $ 307,994 Liabilities and Stockholders’ Equity Current liabilities: Revolving credit facility $ — $ — $ — Accounts payable 10,616 — 10,616 Accrued liabilities 37,455 (580) (b) 36,875 Total current liabilities 48,071 (580) 47,491 Deferred tax liabilities 10,826 (1,567) (a) 9,259 Other long-term liabilities 1,801 — 1,801 Commitments and contingencies Stockholders’ equity: Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued — — — Common stock, $.004 par value, 100,000,000 shares authorized, 51,991,242 and 52,422,801 issued and outstanding at December 31, 2018 and 2017, respectively 208 — 208 Additional paid-in capital — — — Retained earnings 247,291 1,944 (c) 249,235 Total stockholders’ equity 247,499 1,944 249,443 Total liabilities and stockholders’ equity $ 308,197 $ (203) $ 307,994 (a) The correction to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (b) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (c) See descriptions of the stockholders' equity in the consolidated statements of stockholders' equity for the year ended December 31, 2018 in sections below. Consolidated Statements of Stockholders’ Equity Common Stock Paid-in Retained Shares Amount Capital Earnings Total As Previously Reported (in thousands) Balance at December 31, 2017 52,422 $ 210 $ — $ 237,016 $ 237,226 Net income — — — 42,572 42,572 Stock options exercised and restricted 353 1 4,986 — 4,987 stock awards granted Share-based compensation — — 7,374 — 7,374 Stock repurchased and retired (784) (3) (12,360) (15,580) (27,943) Dividends — — — (16,717) (16,717) Balance at December 31, 2018 51,991 208 — 247,291 247,499 Correction Impacts Balance at December 31, 2017 — — — 1,699 1,699 Net income — — — (243) (243) Stock options exercised and restricted — — — — — stock awards granted Share-based compensation — — 488 — 488 Stock repurchased and retired — — (488) 488 — Dividends — — — — — Balance at December 31, 2018 — — — 1,944 1,944 As Corrected — Balance at December 31, 2017 52,422 210 — 238,715 238,925 Net income — — — 42,329 42,329 Stock options exercised and restricted 353 1 4,986 — 4,987 stock awards granted Share-based compensation — — 7,862 — 7,862 Stock repurchased and retired (784) (3) (12,848) (15,092) (27,943) Dividends — — — (16,717) (16,717) Balance at December 31, 2018 51,991 $ 208 $ — $ 249,235 $ 249,443 See descriptions of net income in the consolidated statement of income for the year ended December 31, 2018 in the section above. Consolidated Statements of Stockholders’ Equity Common Stock Paid-in Retained Shares Amount Capital Earnings Total As Previously Reported (in thousands) Balance at December 31, 2016 52,651 $ 211 $ — $ 205,687 $ 205,898 Net income — — — 54,498 54,498 Stock options exercised and restricted 293 1 2,258 — 2,259 stock awards granted Share-based compensation — — 6,458 — 6,458 Stock repurchased and retired (522) (2) (8,716) (9,516) (18,234) Dividends — — — (13,653) (13,653) Balance at December 31, 2017 52,422 210 — 237,016 237,226 Correction Impacts Balance at December 31, 2016 — — — 2,512 2,512 Net income — — — (668) (668) Stock options exercised and restricted — — — — — stock awards granted Share-based compensation — — (145) — (145) Stock repurchased and retired — — 145 (145) — Dividends — — — — — Balance at December 31, 2017 — — — 1,699 1,699 As Corrected Balance at December 31, 2016 52,651 211 — 208,199 208,410 Net income — — — 53,830 53,830 Stock options exercised and restricted 293 1 2,258 — 2,259 stock awards granted Share-based compensation — — 6,313 — 6,313 Stock repurchased and retired (522) (2) (8,571) (9,661) (18,234) Dividends — — — (13,653) (13,653) Balance at December 31, 2017 52,422 $ 210 $ — $ 238,715 $ 238,925 See descriptions of net income in the consolidated statement of income for the year ended December 31, 2017 in the section above. Consolidated Statements of Cash Flows Year Ended December 31, 2018 Year Ended December 31, 2017 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected Operating Activities (in thousands) Net income $ 42,572 $ (243) $ 42,329 $ 54,498 $ (668) $ 53,830 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 17,655 — 17,655 15,007 — 15,007 Amortization of bond premiums 13 — 13 47 — 47 Provision for losses on accounts receivable, net of adjustments 174 — 174 179 — 179 Provision for excess and obsolete inventories 152 — 152 264 — 264 Share-based compensation 7,374 488 7,862 6,458 (145) 6,313 (Gain) loss on disposition of assets (12) — (12) 45 — 45 Foreign currency transaction loss (gain) 55 — 55 (59) — (59) Interest income on note receivable (27) — (27) (25) — (25) Deferred income taxes 2,849 (208) 2,641 (1,554) 805 (749) Changes in assets and liabilities: Accounts receivable (2,832) — (2,832) (7,516) — (7,516) Income tax receivable (4,461) 13 (4,448) 4,596 (5) 4,591 Inventories (5,598) — (5,598) (23,698) — (23,698) Prepaid expenses and other (528) — (528) 98 — 98 Accounts payable (1,176) — (1,176) 3,043 — 3,043 Deferred revenue 412 — 412 258 — 258 Accrued liabilities and donations (1,766) (50) (1,816) 6,353 13 6,366 Net cash provided by operating activities 54,856 — 54,856 57,994 — 57,994 Investing Activities Capital expenditures (37,268) — (37,268) (41,713) — (41,713) Cash paid in business combination (6,377) — (6,377) — — — Proceeds from sale of property, plant and equipment 13 — 13 10 — 10 Investment in certificates of deposits (7,200) — (7,200) (5,280) — (5,280) Maturities of certificates of deposits 10,080 — 10,080 7,912 — 7,912 Purchases of investments held to maturity (9,001) — (9,001) (13,241) — (13,241) Maturities of investments held to maturity 14,570 — 14,570 19,700 — 19,700 Proceeds from called investments 495 — 495 1,500 — 1,500 Principal payments from note receivable 53 — 53 60 — 60 Net cash used in investing activities (34,635) — (34,635) (31,052) — (31,052) Financing Activities Stock options exercised 4,987 — 4,987 2,259 — 2,259 Repurchase of stock (26,846) — (26,846) (16,620) — (16,620) Employee taxes paid by withholding shares (1,097) — (1,097) (1,614) — (1,614) Cash dividends paid to stockholders (16,728) — (16,728) (13,663) — (13,663) Net cash used in financing activities (39,684) — (39,684) (29,638) — (29,638) Net decrease in cash and cash equivalents (19,463) — (19,463) (2,696) — (2,696) Cash and cash equivalents, beginning of year 21,457 — 21,457 24,153 — 24,153 Cash and cash equivalents, end of year $ 1,994 $ — $ 1,994 $ 21,457 $ — $ 21,457

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Estimated Useful Lives	Depreciation is computed using the straight-line method over the following estimated useful lives: Buildings 3 - 40 years Machinery and equipment 3 - 15 years Furniture and fixtures 3 - 7 years

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Accounts Receivable	December 31, 2019 2018 (in thousands) Accounts receivable $ 67,752 $ 54,342 Less: Allowance for doubtful accounts (353) (264) Total, net $ 67,399 $ 54,078
Accounts Receivable (Allowance)	Years Ended December 31, 2019 2018 2017 Allowance for doubtful accounts: (in thousands) Balance, beginning of period $ 264 $ 119 $ 90 Provisions for losses on accounts receivable, net of adjustments 91 174 179 Accounts receivable written off, net of recoveries (2) (29) (150) Balance, end of period $ 353 $ 264 $ 119

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventories	The components of inventories and the related changes in the allowance for excess and obsolete inventories are as follows: December 31, 2019 2018 (in thousands) Raw materials $ 68,842 $ 67,995 Work in process 1,825 4,060 Finished goods 5,578 6,767 76,245 78,822 Less: Allowance for excess and obsolete inventories (2,644) (1,210) Total, net $ 73,601 $ 77,612
Inventories (Allowance)	Years Ended December 31, 2019 2018 2017 Allowance for excess and obsolete inventories: (in thousands) Balance, beginning of period $ 1,210 $ 1,118 $ 1,382 Provisions for excess and obsolete inventories 1,454 152 102 Inventories written off (20) (60) (366) Balance, end of period $ 2,644 $ 1,210 $ 1,118

Warranties (Tables)

Warranties (Tables)	12 Months Ended
	Dec. 31, 2019
Guarantees [Abstract]
Warranty	Changes in the warranty accrual are as follows: Years Ended December 31, 2019 2018 2017 Warranty accrual: (in thousands) Balance, beginning of period $ 11,421 $ 10,483 $ 7,936 Payments made (6,816) (7,869) (8,686) Provisions 8,047 9,669 11,233 Change in estimate — (862) — Balance, end of period $ 12,652 $ 11,421 $ 10,483 Warranty expense: $ 8,047 $ 8,807 $ 11,233

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	At December 31, accrued liabilities were comprised of the following: December 31, 2019 2018 (in thousands) Warranty $ 12,652 $ 11,421 Due to representatives 11,538 11,024 Payroll 5,058 4,182 Profit sharing 1,721 1,255 Workers' compensation 522 567 Medical self-insurance 707 1,207 Customer prepayments 4,627 2,367 Donations 354 150 Employee vacation time 3,804 3,173 Other 3,286 1,529 Total $ 44,269 $ 36,875

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Provision for Income Taxes	The provision (benefit) for income taxes consists of the following: Years Ended December 31, 2019 2018 2017 (in thousands) Current $ 7,282 $ 10,530 $ 21,543 Deferred 6,038 2,641 (749) Total $ 13,320 $ 13,171 $ 20,794
Federal Statutory Income Tax Rate Reconciliation	The reconciliation of the federal statutory income tax rate to the effective income tax rate is as follows: Years Ended December 31, 2019 2018 2017 Federal statutory rate 21 % 21 % 35 % State income taxes, net of federal benefit 5 % 6 % 5 % Remeasurement of deferred taxes — % — % (5) % Domestic manufacturing deduction — % — % (3) % Excess tax benefits (3) % (2) % (3) % Return to provision (1) % — % — % Oklahoma amended tax returns (1) % — % — % Other (1) % (1) % (1) % 20 % 24 % 28 %
Deferred Tax Assets and Liabilities	The significant components of the Company’s deferred tax assets and liabilities are as follows: December 31, 2019 2018 (in thousands) Deferred income tax assets (liabilities): Accounts receivable and inventory reserves $ 835 $ 401 Warranty accrual 3,523 3,105 Other accruals 1,919 2,445 Share-based compensation 3,906 3,264 Donations 194 80 Other, net 2,140 851 Total deferred income tax assets 12,517 10,146 Property & equipment (27,814) (19,405) Total deferred income tax liabilities $ (27,814) $ (19,405) Net deferred income tax liabilities $ (15,297) $ (9,259)

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Summary of Stock Option Assumptions	The following weighted average assumptions were used to determine the fair value of the stock options granted on the original grant date for expense recognition purposes for options granted during December 31, 2019, 2018, and 2017 using a Black Scholes-Merton Model: 2019 2018 2017 Director and Officers: Expected dividend yield $ 0.32 $ 0.26 $ 0.26 Expected volatility 29.54 % 29.73 % 30.81 % Risk-free interest rate 2.40 % 2.20 % 1.90 % Expected life (in years) 5.00 5.00 5.00 Employees: Expected dividend yield $ 0.32 $ 0.26 $ 0.26 Expected volatility 29.54 % 29.82 % 30.67 % Risk-free interest rate 2.38 % 2.51 % 1.89 % Expected life (in years) 5.00 5.00 5.00
Summary of Stock Options Outstanding	The following is a summary of stock options vested and exercisable as of December 31, 2019: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $7.18 - 34.10 451,077 5.44 $ 23.47 $ 11,702 $34.15 - 40.87 86,122 7.82 36.33 1,126 $41.37 - 50.68 1,750 1.81 41.59 14 Total 538,949 5.81 $ 25.58 $ 12,842 The following is a summary of stock options vested and exercisable as of December 31, 2018: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $5.67 - 32.80 456,223 5.72 $ 20.25 $ 6,757 $32.85 - 34.10 42,552 7.47 33.95 47 $34.15 - 42.94 17,202 8.30 35.19 7 Total 515,977 5.95 $ 21.88 $ 6,811 The following is a summary of stock options vested and exercisable as of December 31, 2017: Weighted Average Weighted Range of Number Remaining Average Exercise of Contractual Exercise Intrinsic Prices Shares Life Price Value (in thousands) $4.54 - 22.76 424,130 4.36 $ 12.41 $ 10,303 $23.57 - 32.85 107,456 8.31 30.10 709 $32.90 - 37.30 25,725 9.19 34.07 68 Total 557,311 5.35 $ 16.82 $ 11,080
Summary of Stock Option Activity	A summary of option activity under the plans is as follows: Weighted Average Exercise Options Shares Price Outstanding at December 31, 2018 2,445,849 $ 30.77 Granted 1,975,820 41.50 Exercised (444,389) 28.40 Forfeited or Expired (350,233) 36.78 Outstanding at December 31, 2019 3,627,047 $ 36.32 Exercisable at December 31, 2019 538,949 $ 25.58
Summary of Unvested Restricted Stock Awards	A summary of the unvested restricted stock awards is as follows: Weighted Average Grant date Restricted stock Shares Fair Value Unvested at December 31, 2018 292,450 $ 28.54 Granted 113,018 40.98 Vested (122,278) 26.38 Forfeited (15,706) 34.71 Unvested at December 31, 2019 267,484 $ 34.42
Summary of Grant Date Fair Value of Awards During Period	2019 2018 2017 Grant date fair value of awards during the period: (in thousands) Options $ 20,442 $ 12,932 $ 3,699 Restricted stock 4,631 3,609 4,217 Total $ 25,073 $ 16,541 $ 7,916
Summary of Share-Based Compensation Expense	2019 2018 2017 Share-based compensation expense: (in thousands) Options $ 9,145 $ 5,344 $ 3,095 Restricted stock 2,654 2,518 3,218 Total $ 11,799 $ 7,862 $ 6,313
Summary of Income Tax Benefit Related to Share-Based Compensation	2019 2018 2017 Income tax benefit related to share-based compensation: (in thousands) Options $ 1,197 $ 980 $ 1,413 Restricted stock 575 353 1,051 Total $ 1,772 $ 1,333 $ 2,464

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Schedule of Defined Contribution Plan Disclosures	The Company matches 175% up to 6% of employee contributions of eligible compensation. Additionally, Plan participant forfeitures are used to reduce the cost of the Company contributions. Years Ended December 31, 2019 2018 2017 (in thousands) Contributions made to the defined contribution plan $ 7.0 $ 8.1 $ 6.1
Schedule of Profit Sharing Bonus Plan	We maintain a discretionary profit sharing bonus plan under which approximately 10% of pre-tax profit is paid to eligible employees on a quarterly basis in order to reward employee productivity. Eligible employees are regular full-time employees who are actively employed and working on the first and last days of the calendar quarter and who were employed full-time for at least three full months prior to the beginning of the calendar quarter, excluding the Company's senior leadership team. Years Ended December 31, 2019 2018 2017 (in thousands) Profit sharing bonus plan expense $ 7.4 $ 6.2 $ 8.4
Schedule of Employee Medical Plan	We self-insure for our employee's health insurance. Eligible employees are regular full-time employees who are actively employed and working. Participants are expected to pay a portion of the premium costs for coverage of the benefits provided under the Plan. We estimate our self-insurance liabilities using an analysis provided by our claims administrator and our historical claims experience. In addition, the Company matches 175% of a participating employee's allowed contributions to a qualified health saving account to assist employees with our heath insurance plan deductibles. Years Ended December 31, 2019 2018 2017 (in thousands) Medical claim payments $ 5.9 $ 5.9 $ 4.8 Heath saving account payments 3.3 2.9 2.5

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of Class of Treasury Stock	Our open market repurchase programs are as follows: Agreement Execution Date Authorized Repurchase $ Expiration Date June 2, 2016 $25 million April 15, 2017 May 16, 2018 $15 million March 1, 2019 March 5, 2019 $20 million March 4, 2020
Schedule of Share Repurchases	Our repurchase activity is as follows: 2019 2018 2017 (in thousands, except share and per share data) Program Shares Total $ $ per share Shares Total $ $ per share Shares Total $ $ per share Open market 5,799 $ 200 $ 34.46 252,272 $ 8,374 $ 33.19 8,676 $ 284 $ 32.69 401(k) 419,963 19,386 46.16 497,753 18,472 37.11 467,580 16,336 34.94 Directors & employees 28,668 1,207 42.11 33,751 1,097 32.49 45,878 1,614 35.19 Total 454,430 $ 20,793 $ 45.76 783,776 $ 27,943 $ 35.65 522,134 $ 18,234 $ 34.92 Inception to Date (in thousands, except share and per share data) Program Shares Total $ $ per share Open market 4,101,566 $ 69,806 $ 17.02 401(k) 7,467,739 119,927 16.06 Directors & employees 1,981,929 19,582 9.88 Total 13,551,234 $ 209,315 $ 15.45
Schedule of Dividends	Our recent dividends are as follows: Declaration Date Record Date Payment Date Dividend per Share May 16, 2017 June 9, 2017 July 7, 2017 $0.13 November 7, 2017 November 30, 2017 December 21, 2017 $0.13 May 18, 2018 June 8, 2018 July 6, 2018 $0.16 November 8, 2018 November 29, 2018 December 20, 2018 $0.16 May 20, 2019 June 3, 2019 July 1, 2019 $0.16 November 6, 2019 November 27, 2019 December 18, 2019 $0.16

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share Table	The following table sets forth the computation of basic and diluted earnings per share: 2019 2018 2017 Numerator: (in thousands, except share and per share data) Net income $ 53,711 $ 42,329 $ 53,830 Denominator: Basic weighted average shares 52,079,865 52,284,616 52,572,496 Effect of dilutive stock options and restricted stock 555,550 383,323 506,238 Diluted weighted average shares 52,635,415 52,667,939 53,078,734 Earnings per share: Basic $ 1.03 $ 0.81 $ 1.02 Dilutive $ 1.02 $ 0.80 $ 1.01 Anti-dilutive shares: Shares 1,868,087 1,920,313 785,825

Related Parties (Tables)

Related Parties (Tables)	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Following is a summary of transactions and balances with affiliates: Years Ended December 31, 2019 2018 2017 (in thousands) Sales to affiliates $ 886 $ 1,442 $ 1,579 Payments to affiliates 332 342 432 December 31, 2019 2018 (in thousands) Due from affiliates $ 22 $ 79 Due to affiliates 2 —

Quarterly Results (Unaudited)_2

Quarterly Results (Unaudited) (As Corrected) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations	The following is a summary of the quarterly results of operations for the years ended December 31, 2019 and 2018: Quarter First Second Third Fourth (in thousands, except per share data) 2019 Net sales $ 113,822 $ 119,437 $ 113,500 $ 122,574 Gross profit 25,430 30,204 27,410 36,381 Net income 8,757 13,391 14,290 17,273 Earnings per share: Basic $ 0.17 $ 0.26 $ 0.27 $ 0.33 Diluted $ 0.17 $ 0.26 $ 0.26 $ 0.33 2018 Net sales $ 99,082 $ 109,588 $ 112,937 $ 112,340 Gross profit 15,196 27,661 32,830 27,846 Net income 3,154 11,697 14,514 12,964 Earnings per share: Basic $ 0.06 $ 0.22 $ 0.28 $ 0.25 Diluted $ 0.06 $ 0.22 $ 0.27 $ 0.25 The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended March 31, 2019 and 2018. Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 113,822 $ — $ 113,822 $ 99,082 $ — $ 99,082 Cost of sales 88,029 363 (a) 88,392 83,692 194 (a) 83,886 Gross profit 25,793 (363) 25,430 15,390 (194) 15,196 Selling, general and administrative expenses 11,001 2,676 (b) 13,677 10,219 1,432 (b) 11,651 Loss (gain) on disposal of assets 284 — 284 (7) — (7) Income from operations 14,508 (3,039) 11,469 5,178 (1,626) 3,552 Interest income, net 9 — 9 68 — 68 Other (expense) income, net (26) — (26) (6) — (6) Income before taxes 14,491 (3,039) 11,452 5,240 (1,626) 3,614 Income tax provision 3,589 (894) (c) 2,695 980 (520) (c) 460 Net income $ 10,902 $ (2,145) $ 8,757 $ 4,260 $ (1,106) $ 3,154 Earnings per share: Basic $ 0.21 $ (0.04) $ 0.17 $ 0.08 $ (0.02) $ 0.06 Diluted $ 0.21 $ (0.04) $ 0.17 $ 0.08 $ (0.02) $ 0.06 Weighted average shares outstanding: Basic 51,992,150 — 51,992,150 52,433,902 — 52,433,902 Diluted 52,369,660 — 52,369,660 52,910,223 — 52,910,223 Balance Sheet Data (at end of period): Current assets $ 146,798 $ (287) (c) $ 146,511 $ 154,687 $ (237) (c) $ 154,450 Total assets 319,525 (287) (c) 319,238 306,945 (237) (c) 306,708 Current liabilities 44,000 (918) (d) 43,082 57,292 (711) (d) 56,581 Deferred income taxes 12,713 (2,545) (c) 10,168 8,397 (1,926) (c) 6,471 Other long-term liabilities 3,442 — 3,442 1,645 — 1,645 Total stockholders' equity $ 259,370 $ 3,176 (e) $ 262,546 $ 239,611 $ 2,400 (e) $ 242,011 (a) The share-based compensation correction to cost of sales for the quarters ended March 31, 2019 and 2018 was approximately $0.4 million and $0.2 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended March 31, 2019 and 2018 was approximately $3.0 million and $1.6 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.4 million and $0.2 million for the quarters ended March 31, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation correction. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended June 30, 2019 and 2018. Three Months Ended June 30, 2019 Three Months Ended June 30, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 119,437 $ — $ 119,437 $ 109,588 $ — $ 109,588 Cost of sales 89,262 (29) (a) 89,233 82,003 (76) (a) 81,927 Gross profit 30,175 29 30,204 27,585 76 27,661 Selling, general and administrative expenses 13,481 (569) (b) 12,912 13,086 67 (b) 13,153 Loss (gain) on disposal of assets 6 — 6 (4) — (4) Income from operations 16,688 598 17,286 14,503 9 14,512 Interest income, net 31 — 31 67 — 67 Other (expense) income, net 17 — 17 12 — 12 Income before taxes 16,736 598 17,334 14,582 9 14,591 Income tax provision 3,775 168 (c) 3,943 2,891 3 (c) 2,894 Net income $ 12,961 $ 430 $ 13,391 $ 11,691 $ 6 $ 11,697 Earnings per share: Basic $ 0.25 $ 0.01 $ 0.26 $ 0.22 $ — $ 0.22 Diluted $ 0.25 $ 0.01 $ 0.26 $ 0.22 $ — $ 0.22 Cash dividends declared per common share: $ 0.16 $ — $ 0.16 $ 0.16 $ — $ 0.16 Weighted average shares outstanding: Basic 52,120,272 — 52,120,272 52,383,842 — 52,383,842 Diluted 52,474,199 — 52,474,199 52,717,787 — 52,717,787 Balance Sheet Data (at end of period): Current assets $ 168,630 $ (270) (c) $ 168,360 $ 154,665 $ (237) (c) $ 154,428 Total assets 342,251 (270) (c) 341,981 320,271 (237) (c) 320,034 Current liabilities 58,953 (851) (d) 58,102 71,673 (711) (d) 70,962 Deferred income taxes 14,938 (2,361) (c) 12,577 8,415 (1,922) (c) 6,493 Other long-term liabilities 3,791 — 3,791 1,746 — 1,746 Total stockholders' equity $ 264,569 $ 2,942 (e) $ 267,511 $ 238,437 $ 2,396 (e) $ 240,833 (a) The share-based compensation correction to cost of sales for the quarters ended June 30, 2019 and 2018 was approximately $0.1 million and $0.1 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended June 30, 2019 and 2018 was approximately $0.6 million and $0.1 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the quarters ended June 30, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation correction. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following tables reconcile our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended September 30, 2019 and 2018. Three Months Ended September 30, 2019 Three Months Ended September 30, 2018 Previously Reported Corrections As Corrected Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 113,500 $ — $ 113,500 $ 112,937 $ — $ 112,937 Cost of sales 86,115 (25) (a) 86,090 80,174 (67) (a) 80,107 Gross profit 27,385 25 27,410 32,763 67 32,830 Selling, general and administrative expenses 12,994 (620) (b) 12,374 13,190 (523) (b) 12,667 Loss (gain) on disposal of assets 6 — 6 2 — 2 Income from operations 14,385 645 15,030 19,571 590 20,161 Interest income, net 9 — 9 36 — 36 Other (expense) income, net (7) — (7) 5 — 5 Income before taxes 14,387 645 15,032 19,612 590 20,202 Income tax provision 560 182 (c) 742 5,527 161 (c) 5,688 Net income $ 13,827 $ 463 $ 14,290 $ 14,085 $ 429 $ 14,514 Earnings per share: Basic $ 0.27 $ — $ 0.27 $ 0.27 $ 0.01 $ 0.28 Diluted $ 0.26 $ — $ 0.26 $ 0.27 $ — $ 0.27 Weighted average shares outstanding: Basic 52,111,444 — 52,111,444 52,238,796 — 52,238,796 Diluted 52,722,127 — 52,722,127 52,627,541 — 52,627,541 Balance Sheet Data (at end of period): Current assets $ 170,536 $ (252) (c) $ 170,284 $ 144,696 $ (220) (c) $ 144,476 Total Assets 352,152 (252) (c) 351,900 314,024 (220) (c) 313,804 Current liabilities 53,882 (779) (d) 53,103 53,716 (645) (d) 53,071 Deferred income taxes 15,034 (2,161) (c) 12,873 8,841 (1,744) (c) 7,097 Other long-term liabilities 3,669 — 3,669 1,838 — 1,838 Total stockholders' equity $ 279,567 $ 2,688 (e) $ 282,255 $ 249,629 $ 2,169 (e) $ 251,798 (a) The share-based compensation correction to cost of sales for the quarters ended September 30, 2019 and 2018 was approximately $0.1 million and $0.1 million, respectively. (b) The share-based compensation correction to selling, general and administrative expenses for the quarters ended September 30, 2019 and 2018 was approximately $0.7 million and $0.6 million, respectively. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million and $0.1 million for the quarters ended September 30, 2019 and 2018, respectively. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2019 and 2018. The following table reconciles our previously reported quarterly financial information with the corrected quarterly financial information as of and for the three months ended December 31, 2018. Three Months Ended December 31, 2018 Previously Reported Corrections As Corrected (in thousands, except share and per share data) Net sales $ 112,340 $ — $ 112,340 Cost of sales 84,545 (51) (a) 84,494 Gross profit 27,795 51 27,846 Selling, general and administrative expenses 11,260 (537) (b) 10,723 Loss (gain) on disposal of assets (3) — (3) Income from operations 16,538 588 17,126 Interest income, net 25 — 25 Other (expense) income, net (58) — (58) Income before taxes 16,505 588 17,093 Income tax provision 3,969 160 (c) 4,129 Net income $ 12,536 $ 428 $ 12,964 Earnings per share: Basic $ 0.24 $ 0.01 $ 0.25 Diluted $ 0.24 $ 0.01 $ 0.25 Cash dividends declared per common share: $ 0.16 $ — $ 0.16 Weighted average shares outstanding: Basic 52,086,247 — 52,086,247 Diluted 52,420,529 — 52,420,529 Balance Sheet Data (at end of period): Current assets $ 140,861 $ (203) (c) $ 140,658 Total Assets 308,197 (203) (c) 307,994 Current liabilities 48,071 (580) (d) 47,491 Deferred income taxes 10,826 (1,567) (c) 9,259 Other long-term liabilities 1,801 — 1,801 Total stockholders' equity $ 247,499 $ 1,944 (e) $ 249,443 (a) The share-based compensation correction for cost of sales for the quarter ended December 31, 2018 was approximately $0.1 million. (b) The share-based compensation correction to selling, general and administrative expenses for the quarter ended December 31, 2018 was approximately $0.6 million. Included in the correction to selling, general and administrative expenses is a correction to our employee profit sharing bonus plan (Note 17) of approximately $0.1 million for the quarter ended December 31, 2018. (c) The corrections to income tax receivable and deferred tax liability are the tax effect of the share-based compensation corrections. (d) This is the cumulative reduction of our employee profit sharing bonus plan (Note 17) liability as a result of the share-based compensation correction. The prior period costs will be recovered through our estimated 2019 fourth quarter payment which will be paid in early 2020. (e) This is the cumulative effect on stockholders' equity as result of the share-based compensation correction. See Note 2, Error Correction , for a descriptions of the changes in stockholders' equity in the consolidated statements of stockholders' equity for the years ended December 31, 2018.

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	The following table summarizes certain financial data related to our segments. Transactions between segments are recorded based on prices negotiated between the segments. Sales of units represents the selling price of our units plus freight and other miscellaneous charges less any returns and allowances. Parts includes sales of purchased and fabricated parts including our coils along with the related freight and less any returns and allowances. The “Other” category in the table below includes certain sales cost and expenses that are not allocated to the reportable segments. Asset information by segment is not easily identifiable or reviewed by the chief operating decision maker. As such, this information is not included below. Years Ended December 31, 2019 2018 2017 (in thousands) Sales Units $ 434,283 $ 406,331 $ 384,853 Parts - External 35,424 28,456 22,050 Parts - Inter-segment 28,053 29,385 29,293 Other (374) (840) (1,671) Eliminations (28,053) (29,385) (29,293) Net sales $ 469,333 $ 433,947 $ 405,232 Gross Profit Units $ 121,878 $ 108,214 $ 128,647 Parts - External 17,301 13,215 9,555 Parts - Inter-segment 985 865 426 Other (19,754) (17,896) (14,551) Eliminations (985) (865) (426) Gross profit $ 119,425 $ 103,533 $ 123,651

Error Correction (Restated Cons

Error Correction (Restated Consolidated Statements) (Details) $ / shares in Units, $ in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares	Sep. 30, 2019USD ($)$ / sharesshares	Jun. 30, 2019USD ($)$ / sharesshares	Mar. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2018USD ($)$ / sharesshares	Mar. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Sep. 30, 2010CAD ($)
Income Statement Related Disclosures [Abstract]
Net sales	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 112,340	$ 112,937	$ 109,588	$ 99,082	$ 469,333	$ 433,947	$ 405,232
Cost of sales		86,090	89,233	88,392	84,494	80,107	81,927	83,886	349,908	330,414	281,581
Gross profit	36,381	27,410	30,204	25,430	27,846	32,830	27,661	15,196	119,425	103,533	123,651
Selling, general and administrative expenses		12,374	12,912	13,677	10,723	12,667	13,153	11,651	52,077	48,194	49,371
Loss (gain) on disposition of assets		6	6	284	(3)	2	(4)	(7)	337	(12)	45
Operating Income (Loss)		15,030	17,286	11,469	17,126	20,161	14,512	3,552	67,011	55,351	74,235
Interest income, net		9	31	9	25	36	67	68	66	196	298
Other (expense) income, net		(7)	17	(26)	(58)	5	12	(6)	(46)	(47)	91
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		15,032	17,334	11,452	17,093	20,202	14,591	3,614	67,031	55,500	74,624
Income tax provision		742	3,943	2,695	4,129	5,688	2,894	460	13,320	13,171	20,794
Net income	$ 17,273	$ 14,290	$ 13,391	$ 8,757	$ 12,964	$ 14,514	$ 11,697	$ 3,154	$ 53,711	$ 42,329	$ 53,830
Earnings per share:
Basic (usd per share) | $ / shares	$ 0.33	$ 0.27	$ 0.26	$ 0.17	$ 0.25	$ 0.28	$ 0.22	$ 0.06	$ 1.03	$ 0.81	$ 1.02
Diluted (usd per share) | $ / shares	$ 0.33	$ 0.26	0.26	$ 0.17	0.25	$ 0.27	0.22	$ 0.06	1.02	0.80	1.01
Cash dividends declared per common share (in dollars per share) | $ / shares			$ 0.16		$ 0.16		$ 0.16		$ 0.32	$ 0.32	$ 0.26
Weighted average shares outstanding:
Basic weighted average shares (in shares) | shares		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902	52,079,865	52,284,616	52,572,496
Weighted Average Number of Shares Outstanding, Diluted | shares		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223	52,635,415	52,667,939	53,078,734
Current assets:
Cash and cash equivalents	$ 26,797				$ 1,994				$ 26,797	$ 1,994
Accounts receivable, net	67,399				54,078				67,399	54,078
Income tax receivable	772				5,901				772	5,901
Note receivable	29				27				29	27
Inventories, net	73,601				77,612				73,601	77,612
Prepaid expenses and other	1,375				1,046				1,375	1,046
Current assets	187,549	$ 170,284	$ 168,360	$ 146,511	140,658	$ 144,476	$ 154,428	$ 154,450	187,549	140,658
Property, plant and equipment:
Land	3,274				3,114				3,274	3,114
Buildings	101,113				97,393				101,113	97,393
Machinery and equipment	236,087				212,779				236,087	212,779
Furniture and fixtures	16,862				16,597				16,862	16,597
Property, Plant and Equipment, Gross	357,336				329,883				357,336	329,883
Less: Accumulated depreciation	179,242				166,880				179,242	166,880
Property, Plant and Equipment, Net	178,094				163,003				178,094	163,003
Intangible assets, net	272				506				272	506
Goodwill	3,229				3,229				3,229	3,229
Note receivable, long-term	597				598				597	598			$ 1.1
Total assets	371,424	351,900	341,981	319,238	307,994	313,804	320,034	306,708	371,424	307,994
Current liabilities:
Revolving credit facility	0				0				0	0
Accounts payable	11,759				10,616				11,759	10,616
Accrued liabilities	44,269				36,875				44,269	36,875
Current liabilities	56,028	53,103	58,102	43,082	47,491	53,071	70,962	56,581	56,028	47,491
Deferred tax liabilities	15,297	12,873	12,577	10,168	9,259	7,097	6,493	6,471	15,297	9,259
Other long-term liabilities	3,639	3,669	3,791	3,442	1,801	1,838	1,746	1,645	3,639	1,801
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued	0				0				0	0
Common stock, $.004 par value, 100,000,000 shares authorized, 52,078,515 and 51,991,242 issued and outstanding at December 31, 2019 and 2018, respectively	208				208				208	208
Additional paid-in capital	3,631				0				3,631	0
Retained earnings	286,301				249,235				286,301	249,235
Total stockholders' equity	290,140	282,255	267,511	262,546	249,443	251,798	240,833	242,011	290,140	249,443	$ 238,925	$ 208,410
Liabilities and Equity	$ 371,424				$ 307,994				$ 371,424	$ 307,994
Parenthetical Disclosure
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001				$ 0.001				$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares) | shares	5,000,000				5,000,000				5,000,000	5,000,000
Preferred stock, shares issued (in shares) | shares	0				0				0	0
Common stock, par value (in dollars per share) | $ / shares	$ 0.004				$ 0.004				$ 0.004	$ 0.004	$ 0.004
Common stock, shares authorized (in shares) | shares	100,000,000				100,000,000				100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares) | shares	52,078,515				51,991,242				52,078,515	51,991,242	52,422,801
Common stock, shares outstanding (in shares) | shares	52,078,515				51,991,242				52,078,515	51,991,242	52,422,801
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity	$ 290,140	282,255	267,511	262,546	$ 249,443	251,798	240,833	242,011	$ 290,140	$ 249,443	$ 238,925	208,410
Net income	17,273	14,290	13,391	8,757	12,964	14,514	11,697	3,154	53,711	42,329	53,830
Stock options exercised and restricted stock awards granted									12,625	4,987	2,259
Share-based compensation									11,799	7,862	6,313
Stock Repurchased and Retired During Period, Value									20,793	27,943	18,234
Dividends, Common Stock, Cash									16,645	16,717	13,653
Operating Activities
Net income	17,273	14,290	13,391	8,757	12,964	14,514	11,697	3,154	53,711	42,329	53,830
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									22,766	17,655	15,007
Amortization of bond premiums									0	13	47
Provision for losses on accounts receivable, net of adjustments									91	174	179
Provision for excess and obsolete inventories									1,454	152	264
Share-based Compensation									11,799	7,862	6,313
Loss (gain) on disposition of assets		6	6	284	(3)	2	(4)	(7)	337	(12)	45
Foreign currency transaction (gain) loss									(27)	55	(59)
Interest income on note receivable									(25)	(27)	(25)
Deferred income taxes									6,038	2,641	(749)
Changes in assets and liabilities:
Accounts receivable									(13,412)	(2,832)	(7,516)
Income tax receivable									5,129	(4,448)	4,591
Inventories									2,557	(5,598)	(23,698)
Prepaid expenses and other									(329)	(528)	98
Accounts payable									280	(1,176)	3,043
Deferred revenue									425	412	258
Accrued liabilities and donations									7,124	(1,816)	6,366
Net cash provided by operating activities									97,925	54,856	57,994
Investing Activities
Payments to Acquire Productive Assets									37,166	37,268	41,713
Payments to Acquire Businesses, Net of Cash Acquired									0	6,377	0
Proceeds from sale of property, plant and equipment									69	13	10
Payments to Acquire Other Investments									6,000	7,200	5,280
Maturities of certificates of deposits									6,000	10,080	7,912
Payments to Acquire Held-to-maturity Securities									0	9,001	13,241
Maturities of investments held to maturity									0	14,570	19,700
Proceeds from called investments									0	495	1,500
Principal payments from note receivable									51	53	60
Net cash used in investing activities									(37,046)	(34,635)	(31,052)
Financing Activities
Stock options exercised									12,625	4,987	2,259
Repurchase of stock									(19,586)	(26,846)	(16,620)
Employee taxes paid by withholding shares									(1,207)	(1,097)	(1,614)
Cash dividends paid to stockholders									(16,645)	(16,728)	(13,663)
Net cash used in financing activities									(18,500)	(39,684)	(29,638)
Net increase (decrease) in cash, cash equivalents and restricted cash									42,379	(19,463)	(2,696)
Cash, cash equivalents and restricted cash, beginning of year				1,994				21,457	1,994	21,457	24,153
Cash, cash equivalents and restricted cash, end of year	44,373				1,994				44,373	1,994	21,457
Common Stock
Stockholders’ equity:
Total stockholders' equity	$ 208				$ 208				$ 208	$ 208	$ 210	$ 211
Statement of Stockholders' Equity [Abstract]
Shares, Outstanding | shares	52,079,000				51,991,000				52,079,000	51,991,000	52,422,000	52,651,000
Total stockholders' equity	$ 208				$ 208				$ 208	$ 208	$ 210	$ 211
Stock options exercised and restricted stock awards granted (in shares) | shares									542,000	353,000	293,000
Stock options exercised and restricted stock awards granted									$ 2	$ 1	$ 1
Stock Repurchased and Retired During Period, Shares | shares									454,000	784,000	522,000
Stock Repurchased and Retired During Period, Value									$ 2	$ 3	$ 2
Paid-in Capital
Stockholders’ equity:
Total stockholders' equity	3,631				0				3,631	0	0	0
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity	3,631				0				3,631	0	0	0
Stock options exercised and restricted stock awards granted									12,623	4,986	2,258
Share-based compensation									11,799	7,862	6,313
Stock Repurchased and Retired During Period, Value									20,791	12,848	8,571
Retained Earnings
Income Statement Related Disclosures [Abstract]
Net income									53,711	42,329	53,830
Stockholders’ equity:
Total stockholders' equity	286,301				249,235				286,301	249,235	238,715	208,199
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity	$ 286,301				249,235				286,301	249,235	238,715	208,199
Net income									53,711	42,329	53,830
Stock Repurchased and Retired During Period, Value									0	15,092	9,661
Dividends, Common Stock, Cash									16,645	16,717	13,653
Operating Activities
Net income									53,711	42,329	53,830
Previously Reported
Income Statement Related Disclosures [Abstract]
Net sales		113,500	119,437	113,822	112,340	112,937	109,588	99,082		433,947	405,232
Cost of sales		86,115	89,262	88,029	84,545	80,174	82,003	83,692		330,414	281,835
Gross profit		27,385	30,175	25,793	27,795	32,763	27,585	15,390		103,533	123,397
Selling, general and administrative expenses		12,994	13,481	11,001	11,260	13,190	13,086	10,219		47,755	49,249
Loss (gain) on disposition of assets		6	6	284	(3)	2	(4)	(7)		(12)	45
Operating Income (Loss)		14,385	16,688	14,508	16,538	19,571	14,503	5,178		55,790	74,103
Interest income, net		9	31	9	25	36	67	68		196	298
Other (expense) income, net		(7)	17	(26)	(58)	5	12	(6)		(47)	91
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		14,387	16,736	14,491	16,505	19,612	14,582	5,240		55,939	74,492
Income tax provision		560	3,775	3,589	3,969	5,527	2,891	980		13,367	19,994
Net income		$ 13,827	$ 12,961	$ 10,902	$ 12,536	$ 14,085	$ 11,691	$ 4,260		$ 42,572	$ 54,498
Earnings per share:
Basic (usd per share) | $ / shares		$ 0.27	$ 0.25	$ 0.21	$ 0.24	$ 0.27	$ 0.22	$ 0.08		$ 0.81	$ 1.04
Diluted (usd per share) | $ / shares		$ 0.26	0.25	$ 0.21	0.24	$ 0.27	0.22	$ 0.08		0.81	1.03
Cash dividends declared per common share (in dollars per share) | $ / shares			$ 0.16		$ 0.16		$ 0.16			$ 0.32	$ 0.26
Weighted average shares outstanding:
Basic weighted average shares (in shares) | shares		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902		52,284,616	52,572,496
Weighted Average Number of Shares Outstanding, Diluted | shares		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223		52,667,939	53,078,734
Current assets:
Cash and cash equivalents					$ 1,994					$ 1,994
Accounts receivable, net					54,078					54,078
Income tax receivable					6,104					6,104
Note receivable					27					27
Inventories, net					77,612					77,612
Current assets		$ 170,536	$ 168,630	$ 146,798	140,861	$ 144,696	$ 154,665	$ 154,687		140,861
Property, plant and equipment:
Land					3,114					3,114
Buildings					97,393					97,393
Machinery and equipment					212,779					212,779
Furniture and fixtures					16,597					16,597
Property, Plant and Equipment, Gross					329,883					329,883
Less: Accumulated depreciation					166,880					166,880
Property, Plant and Equipment, Net					163,003					163,003
Intangible assets, net					506					506
Goodwill					3,229					3,229
Note receivable, long-term					598					598
Total assets		352,152	342,251	319,525	308,197	314,024	320,271	306,945		308,197
Current liabilities:
Revolving credit facility					0					0
Accounts payable					10,616					10,616
Accrued liabilities					37,455					37,455
Current liabilities		53,882	58,953	44,000	48,071	53,716	71,673	57,292		48,071
Deferred tax liabilities		15,034	14,938	12,713	10,826	8,841	8,415	8,397		10,826
Other long-term liabilities		3,669	3,791	3,442	1,801	1,838	1,746	1,645		1,801
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued					0					0
Common stock, $.004 par value, 100,000,000 shares authorized, 52,078,515 and 51,991,242 issued and outstanding at December 31, 2019 and 2018, respectively					208					208
Additional paid-in capital					0					0
Retained earnings					247,291					247,291
Total stockholders' equity		279,567	264,569	259,370	247,499	249,629	238,437	239,611		247,499	$ 237,226	205,898
Liabilities and Equity					308,197					308,197
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity		279,567	264,569	259,370	247,499	249,629	238,437	239,611		247,499	237,226	205,898
Net income		13,827	12,961	10,902	12,536	14,085	11,691	4,260		42,572	54,498
Stock options exercised and restricted stock awards granted										4,987	2,259
Share-based compensation										7,374	6,458
Stock Repurchased and Retired During Period, Value										27,943	18,234
Dividends, Common Stock, Cash										16,717	13,653
Operating Activities
Net income		13,827	12,961	10,902	12,536	14,085	11,691	4,260		42,572	54,498
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization										17,655	15,007
Amortization of bond premiums										13	47
Provision for losses on accounts receivable, net of adjustments										174	179
Provision for excess and obsolete inventories										152	264
Share-based Compensation										7,374	6,458
Loss (gain) on disposition of assets		6	6	284	(3)	2	(4)	(7)		(12)	45
Foreign currency transaction (gain) loss										55	(59)
Interest income on note receivable										(27)	(25)
Deferred income taxes										2,849	(1,554)
Changes in assets and liabilities:
Accounts receivable										(2,832)	(7,516)
Income tax receivable										(4,461)	4,596
Inventories										(5,598)	(23,698)
Prepaid expenses and other										(528)	98
Accounts payable										(1,176)	3,043
Deferred revenue										412	258
Accrued liabilities and donations										(1,766)	6,353
Net cash provided by operating activities										54,856	57,994
Investing Activities
Payments to Acquire Productive Assets										37,268	41,713
Payments to Acquire Businesses, Net of Cash Acquired										6,377	0
Proceeds from sale of property, plant and equipment										13	10
Payments to Acquire Other Investments										7,200	5,280
Maturities of certificates of deposits										10,080	7,912
Payments to Acquire Held-to-maturity Securities										9,001	13,241
Maturities of investments held to maturity										14,570	19,700
Proceeds from called investments										495	1,500
Principal payments from note receivable										53	60
Net cash used in investing activities										(34,635)	(31,052)
Financing Activities
Stock options exercised										4,987	2,259
Repurchase of stock										(26,846)	(16,620)
Employee taxes paid by withholding shares										(1,097)	(1,614)
Cash dividends paid to stockholders										(16,728)	(13,663)
Net cash used in financing activities										(39,684)	(29,638)
Net increase (decrease) in cash, cash equivalents and restricted cash										(19,463)	(2,696)
Cash, cash equivalents and restricted cash, beginning of year				1,994				21,457	1,994	21,457	24,153
Cash, cash equivalents and restricted cash, end of year					1,994					1,994	21,457
Previously Reported | Common Stock
Stockholders’ equity:
Total stockholders' equity					$ 208					$ 208	$ 210	$ 211
Statement of Stockholders' Equity [Abstract]
Shares, Outstanding | shares					51,991,000					51,991,000	52,422,000	52,651,000
Total stockholders' equity					$ 208					$ 208	$ 210	$ 211
Stock options exercised and restricted stock awards granted (in shares) | shares										353,000	293,000
Stock options exercised and restricted stock awards granted										$ 1	$ 1
Stock Repurchased and Retired During Period, Shares | shares										784,000	522,000
Stock Repurchased and Retired During Period, Value										$ 3	$ 2
Previously Reported | Paid-in Capital
Stockholders’ equity:
Total stockholders' equity					0					0	0	0
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity					0					0	0	0
Stock options exercised and restricted stock awards granted										4,986	2,258
Share-based compensation										7,374	6,458
Stock Repurchased and Retired During Period, Value										12,360	8,716
Previously Reported | Retained Earnings
Income Statement Related Disclosures [Abstract]
Net income										42,572	54,498
Stockholders’ equity:
Total stockholders' equity					247,291					247,291	237,016	205,687
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity					247,291					247,291	237,016	205,687
Net income										42,572	54,498
Stock Repurchased and Retired During Period, Value										15,580	9,516
Dividends, Common Stock, Cash										16,717	13,653
Operating Activities
Net income										42,572	54,498
Corrections
Income Statement Related Disclosures [Abstract]
Net sales		0	0	0	0	0	0	0		0	0
Cost of sales		(25)	(29)	363	(51)	(67)	(76)	194		0	(254)
Gross profit		25	29	(363)	51	67	76	(194)		0	254
Selling, general and administrative expenses		(620)	(569)	2,676	(537)	(523)	67	1,432		439	122
Loss (gain) on disposition of assets		0	0	0	0	0	0	0		0	0
Operating Income (Loss)		645	598	(3,039)	588	590	9	(1,626)		(439)	132
Interest income, net		0	0	0	0	0	0	0		0	0
Other (expense) income, net		0	0	0	0	0	0	0		0	0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		645	598	(3,039)	588	590	9	(1,626)		(439)	132
Income tax provision		182	168	(894)	160	161	3	(520)		(196)	800
Net income		$ 463	$ 430	$ (2,145)	$ 428	$ 429	$ 6	$ (1,106)		$ (243)	$ (668)
Earnings per share:
Basic (usd per share) | $ / shares		$ 0	$ 0.01	$ (0.04)	$ 0.01	$ 0.01	$ 0	$ (0.02)		$ 0	$ (0.02)
Diluted (usd per share) | $ / shares		$ 0	0.01	$ (0.04)	0.01	$ 0	0	$ (0.02)		(0.01)	(0.02)
Cash dividends declared per common share (in dollars per share) | $ / shares			$ 0		$ 0		$ 0			$ 0	$ 0
Weighted average shares outstanding:
Basic weighted average shares (in shares) | shares		0	0	0	0	0	0	0		0	0
Weighted Average Number of Shares Outstanding, Diluted | shares		0	0	0	0	0	0	0		0	0
Current assets:
Cash and cash equivalents					$ 0					$ 0
Accounts receivable, net					0					0
Income tax receivable					(203)					(203)
Note receivable					0					0
Inventories, net					0					0
Prepaid expenses and other					0					0
Current assets		$ (252)	$ (270)	$ (287)	(203)	$ (220)	$ (237)	$ (237)		(203)
Property, plant and equipment:
Land					0					0
Buildings					0					0
Machinery and equipment					0					0
Furniture and fixtures					0					0
Property, Plant and Equipment, Gross					0					0
Less: Accumulated depreciation					0					0
Property, Plant and Equipment, Net					0					0
Intangible assets, net					0					0
Goodwill					0					0
Note receivable, long-term					0					0
Total assets		(252)	(270)	(287)	(203)	(220)	(237)	(237)		(203)
Current liabilities:
Revolving credit facility					0					0
Accounts payable					0					0
Accrued liabilities					(580)					(580)
Current liabilities		(779)	(851)	(918)	(580)	(645)	(711)	(711)		(580)
Deferred tax liabilities		(2,161)	(2,361)	(2,545)	(1,567)	(1,744)	(1,922)	(1,926)		(1,567)
Other long-term liabilities		0	0	0	0	0	0	0		0
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued					0					0
Common stock, $.004 par value, 100,000,000 shares authorized, 52,078,515 and 51,991,242 issued and outstanding at December 31, 2019 and 2018, respectively					0					0
Additional paid-in capital					0					0
Retained earnings					1,944					1,944
Total stockholders' equity		2,688	2,942	3,176	1,944	2,169	2,396	2,400		1,944	$ 1,699	2,512
Liabilities and Equity					(203)					(203)
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity		2,688	2,942	3,176	1,944	2,169	2,396	2,400		1,944	1,699	2,512
Net income		463	430	(2,145)	428	429	6	(1,106)		(243)	(668)
Stock options exercised and restricted stock awards granted										0	0
Share-based compensation										488	(145)
Stock Repurchased and Retired During Period, Value										0	0
Dividends, Common Stock, Cash										0	0
Operating Activities
Net income		463	430	(2,145)	428	429	6	(1,106)		(243)	(668)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization										0	0
Amortization of bond premiums										0	0
Provision for losses on accounts receivable, net of adjustments										0	0
Provision for excess and obsolete inventories										0	0
Share-based Compensation										488	(145)
Loss (gain) on disposition of assets		$ 0	$ 0	0	0	$ 0	$ 0	0		0	0
Foreign currency transaction (gain) loss										0	0
Interest income on note receivable										0	0
Deferred income taxes										(208)	805
Changes in assets and liabilities:
Accounts receivable										0	0
Income tax receivable										13	(5)
Inventories										0	0
Prepaid expenses and other										0	0
Accounts payable										0	0
Deferred revenue										0	0
Accrued liabilities and donations										(50)	13
Net cash provided by operating activities										0	0
Investing Activities
Payments to Acquire Productive Assets										0	0
Payments to Acquire Businesses, Net of Cash Acquired										0	0
Proceeds from sale of property, plant and equipment										0	0
Payments to Acquire Other Investments										0	0
Maturities of certificates of deposits										0	0
Payments to Acquire Held-to-maturity Securities										0	0
Maturities of investments held to maturity										0	0
Proceeds from called investments										0	0
Principal payments from note receivable										0	0
Net cash used in investing activities										0	0
Financing Activities
Stock options exercised										0	0
Repurchase of stock										0	0
Employee taxes paid by withholding shares										0	0
Cash dividends paid to stockholders										0	0
Net cash used in financing activities										0	0
Net increase (decrease) in cash, cash equivalents and restricted cash										0	0
Cash, cash equivalents and restricted cash, beginning of year				$ 0				$ 0	$ 0	0	0
Cash, cash equivalents and restricted cash, end of year					0					0	0
Corrections | Common Stock
Stockholders’ equity:
Total stockholders' equity					$ 0					$ 0	$ 0	$ 0
Statement of Stockholders' Equity [Abstract]
Shares, Outstanding | shares					0					0	0	0
Total stockholders' equity					$ 0					$ 0	$ 0	$ 0
Stock options exercised and restricted stock awards granted (in shares) | shares										0	0
Stock options exercised and restricted stock awards granted										$ 0	$ 0
Stock Repurchased and Retired During Period, Shares | shares										0	0
Stock Repurchased and Retired During Period, Value										$ 0	$ 0
Corrections | Paid-in Capital
Stockholders’ equity:
Total stockholders' equity					0					0	0	0
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity					0					0	0	0
Stock options exercised and restricted stock awards granted										0	0
Share-based compensation										488	(145)
Stock Repurchased and Retired During Period, Value										488	(145)
Corrections | Retained Earnings
Income Statement Related Disclosures [Abstract]
Net income										(243)	(668)
Stockholders’ equity:
Total stockholders' equity					1,944					1,944	1,699	2,512
Statement of Stockholders' Equity [Abstract]
Total stockholders' equity					$ 1,944					1,944	1,699	$ 2,512
Net income										(243)	(668)
Stock Repurchased and Retired During Period, Value										(488)	145
Dividends, Common Stock, Cash										0	0
Operating Activities
Net income										$ (243)	$ (668)

Error Correction (Narrative) (D

Error Correction (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation								$ 11,799,000	$ 7,862,000	$ 6,313,000
Employee profit sharing bonus plan								$ 7,400,000	6,200,000	8,400,000
Corrections | Cost of Sales
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		0	300,000
Corrections | Selling, General and Administrative Expenses
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	700,000	600,000	3,000,000	(600,000)	(600,000)	100,000	1,600,000		500,000	100,000
Employee profit sharing bonus plan	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		$ 100,000	$ 100,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended							12 Months Ended
	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)numberOfEntitiescustomer	Dec. 31, 2018USD ($)customer	Dec. 31, 2017USD ($)customer
Schedule of Accounting Policies [Line Items]
Number of Veriable Interes Entities | numberOfEntities								2
Certificates of deposit				$ 0				$ 0	$ 0
Investments held to maturity				0				0	0
Research and development costs								14,800,000	13,500,000	$ 13,000,000
Advertising expense								800,000	800,000	1,700,000
Cost of sales	$ 86,090,000	$ 89,233,000	$ 88,392,000	$ 84,494,000	$ 80,107,000	$ 81,927,000	$ 83,886,000	$ 349,908,000	330,414,000	281,581,000
Vesting percentage								20.00%
Payments to representatives								$ 46,100,000	47,800,000	51,800,000
Extended product warranties, minimum length								6 months
Extended product warranties, maximum length								10 years
Shipping and Handling
Schedule of Accounting Policies [Line Items]
Cost of sales								$ 14,400,000	$ 12,600,000	$ 11,400,000
Foreign Sales Revenue, Net
Schedule of Accounting Policies [Line Items]
Concentration risk, percentage								3.00%	3.00%	4.00%
Sales Revenue, Net
Schedule of Accounting Policies [Line Items]
Number of major customers | customer								1	1	1
Accounts Receivable
Schedule of Accounting Policies [Line Items]
Number of major customers | customer								1,000,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2019
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Furniture and Fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and Fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
Leases [Abstract]
Right of use assets	$ 1,683	$ 1,800
Operating Lease, Liability		$ 1,800

Accounts Receivable (Balance) (

Accounts Receivable (Balance) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Accounts receivable	$ 67,752	$ 54,342
Less: Allowance for doubtful accounts	(353)	(264)
Total, net	$ 67,399	$ 54,078

Accounts Receivable (Allowance)

Accounts Receivable (Allowance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts:
Balance, beginning of period	$ 264	$ 119	$ 90
Provision for losses on accounts receivable, net of adjustments	91	174	179
Accounts receivable written off, net of recoveries	(2)	(29)	(150)
Balance, end of period	$ 353	$ 264	$ 119

Inventories - Components (Detai

Inventories - Components (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 68,842	$ 67,995
Work in process	1,825	4,060
Finished goods	5,578	6,767
Inventory, gross	76,245	78,822
Less: Allowance for excess and obsolete inventories	(2,644)	(1,210)	$ (1,118)	$ (1,382)
Total, net	$ 73,601	$ 77,612

Inventories - Allowance (Detail

Inventories - Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for excess and obsolete inventories:
Balance, beginning of period	$ 1,210	$ 1,118	$ 1,382
Provisions for excess and obsolete inventories	1,454	152	102
Inventories written off	(20)	(60)	(366)
Balance, end of period	$ 2,644	$ 1,210	$ 1,118

Note Receivable (Details)

Note Receivable (Details) $ in Thousands, $ in Millions	Sep. 30, 2010CAD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Note Receivable [Abstract]
Note receivable	$ 1.1	$ 597	$ 598
Term	15 years
Interest rate	4.00%
Balloon payment on note receivable	$ 0.6
Balloon payment due date		October 2025
Financing receivable impairment charge		$ 0	$ 0

Warranties - Narrative (Details

Warranties - Narrative (Details)	12 Months Ended
	Dec. 31, 2019
Guarantees [Abstract]
Product warranty accrual, minimum length	18 months
Product warranty accrual, maximum length	25 years

Warranties - Changes in Warrant

Warranties - Changes in Warrants (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Warranty accrual:
Balance, beginning of period	$ 11,421	$ 10,483	$ 7,936
Payments made	(6,816)	(7,869)	(8,686)
Provisions	8,047	9,669	11,233
Change in estimate	0	(862)	0
Balance, end of period	12,652	11,421	10,483
Warranty expense	$ 8,047	$ 8,807	$ 11,233

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Warranty	$ 12,652	$ 11,421
Due to representatives	11,538	11,024
Payroll	5,058	4,182
Profit sharing	1,721	1,255
Workers' compensation	522	567
Medical self-insurance	707	1,207
Customer prepayments	4,627	2,367
Donations	354	150
Employee vacation time	3,804	3,173
Other	3,286	1,529
Total	$ 44,269	$ 36,875

Revolving Credit Facility (Deta

Revolving Credit Facility (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Oct. 24, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Actual net worth for compliance	$ 290,100,000
Minimum net worth required for compliance	$ 175,000,000
Ratio of total liability to net worth	0.3
Maximum ratio of total liability to net worth for compliance	2
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility maximum borrowings	$ 30,000,000	$ 23,000,000
Standby letter of credit	1,700,000
Borrowings available under the revolving credit facility	$ 28,300,000
Frequency of periodic payments	monthly
Fees associated with unused portion of committed amount	$ 0
Borrowings outstanding under revolving credit facility	$ 0		$ 0
Weighted average interest rate	4.30%		4.20%
Percent of ownership previously required		25.00%
Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Stated percentage	2.00%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Doubling bonus depreciation for five years, percent	100.00%								100.00%
Tax Cuts and Jobs Act of 2017, income tax benefit	$ 3,700
Tax Cuts and Jobs Act of 2017, Change in tax rate, bonus depreciation	$ 3,200
Deduction to effective income tax rate, percent									3.00%
Additional income tax expense (benefit)										$ (600)
Percent of eligible investments for state and local tax credit	1.00%								1.00%
Executive compensation limitation	$ 1,000								$ 1,000
Income Tax Examination [Line Items]
Income tax provision		$ 742	$ 3,943	$ 2,695	$ 4,129	$ 5,688	$ 2,894	$ 460	$ 13,320	13,171	$ 20,794
State and Local Jurisdiction
Income Tax Examination [Line Items]
Income tax provision										$ (1,200)

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current								$ 7,282	$ 10,530	$ 21,543
Deferred								6,038	2,641	(749)
Total	$ 742	$ 3,943	$ 2,695	$ 4,129	$ 5,688	$ 2,894	$ 460	$ 13,320	$ 13,171	$ 20,794

Income Taxes - Federal Statutor

Income Taxes - Federal Statutory Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%	35.00%
State income taxes, net of federal benefit	5.00%	6.00%	5.00%
Remeasurement of deferred taxes	0.00%	0.00%	5.00%
Domestic manufacturing deduction	0.00%	0.00%	(3.00%)
Excess tax benefits	(3.00%)	(2.00%)	(3.00%)
Return to provision	1.00%	0.00%	0.00%
Oklahoma amended tax returns	1.00%	0.00%	0.00%
Other	(1.00%)	(1.00%)	(1.00%)
Total	20.00%	24.00%	28.00%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Net long-term deferred assets and (liabilities) relating to:
Accounts receivable and inventory reserves	$ 835	$ 401
Warranty accrual	3,523	3,105
Other accruals	1,919	2,445
Share-based compensation	3,906	3,264
Donations	194	80
Other, net	2,140	851
Total deferred income tax assets	12,517	10,146
Property & equipment	(27,814)	(19,405)
Total deferred income tax liabilities	(27,814)	(19,405)
Net deferred income tax liabilities	$ 15,297	$ 9,259

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	May 24, 2016	May 22, 2007	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 15, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock authorized to be issued under plan (in shares)	6,400,000
Total intrinsic value of options exercised during period			$ 8,100	$ 5,400	$ 4,500
Cash received from options exercised during period			12,625	$ 4,987	$ 2,259
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized pre-tax compensation cost			$ 19,400
Weighted average recognition period (in years)			3 years 6 months 29 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized pre-tax compensation cost			$ 4,600
Weighted average recognition period (in years)			2 years 7 months 20 days
2007 Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock authorized to be issued under plan (in shares)	400,000	3,300,000
Award vesting period		5 years
Exercise price of shares granted may not be less than fair market value (percentage)		100.00%
2016 Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock authorized to be issued under plan (in shares)	3,400,000					2,600,000
Exercise price of shares granted may not be less than fair market value (percentage)	100.00%

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Assumptions (Details) - 2007 Long-Term Incentive Plan	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Director and Officers
Expected dividend yield	32.00%	26.00%	26.00%
Expected volatility	29.54%	29.73%	30.81%
Risk-free interest rate	2.40%	2.20%	1.90%
Expected life (in years)	5 years	5 years	5 years
Employees
Expected dividend yield	32.00%	26.00%	26.00%
Expected volatility	29.54%	29.82%	30.67%
Risk-free interest rate	2.38%	2.51%	1.89%
Expected life (in years)	5 years	5 years	5 years

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Options Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares vested and exercisable (in shares)	538,949	515,977	557,311
Options vested and exercisable weighted average remaining contractual life	5 years 9 months 21 days	5 years 11 months 12 days	5 years 4 months 6 days
Options vested and exercisable weighted average exercise price (in dollars per share)	$ 25.58	$ 21.88	$ 16.82
Options vested and exercisable intrinsic value	$ 12,842	$ 6,811	$ 11,080
$7.18 - 34.10
Range of exercise prices, lower range	$ 7.18
Range of exercise prices, upper range	$ 34.10
Number of shares vested and exercisable (in shares)	451,077
Options vested and exercisable weighted average remaining contractual life	5 years 5 months 8 days
Options vested and exercisable weighted average exercise price (in dollars per share)	$ 23.47
Options vested and exercisable intrinsic value	$ 11,702
$34.15 - 40.87
Range of exercise prices, lower range	$ 34.15
Range of exercise prices, upper range	$ 40.87
Number of shares vested and exercisable (in shares)	86,122
Options vested and exercisable weighted average remaining contractual life	7 years 9 months 25 days
Options vested and exercisable weighted average exercise price (in dollars per share)	$ 36.33
Options vested and exercisable intrinsic value	$ 1,126
$41.37 - 50.68
Range of exercise prices, lower range	$ 41.37
Range of exercise prices, upper range	$ 50.68
Number of shares vested and exercisable (in shares)	1,750
Options vested and exercisable weighted average remaining contractual life	1 year 9 months 21 days
Options vested and exercisable weighted average exercise price (in dollars per share)	$ 41.59
Options vested and exercisable intrinsic value	$ 14
$5.67 - 32.80
Range of exercise prices, lower range		$ 5.67
Range of exercise prices, upper range		$ 32.80
Number of shares vested and exercisable (in shares)		456,223
Options vested and exercisable weighted average remaining contractual life		5 years 8 months 19 days
Options vested and exercisable weighted average exercise price (in dollars per share)		$ 20.25
Options vested and exercisable intrinsic value		$ 6,757
$32.85 - 34.10
Range of exercise prices, lower range		$ 32.85
Range of exercise prices, upper range		$ 34.10
Number of shares vested and exercisable (in shares)		42,552
Options vested and exercisable weighted average remaining contractual life		7 years 5 months 19 days
Options vested and exercisable weighted average exercise price (in dollars per share)		$ 33.95
Options vested and exercisable intrinsic value		$ 47
$34.15 - 42.94
Range of exercise prices, lower range		$ 34.15
Range of exercise prices, upper range		$ 42.94
Number of shares vested and exercisable (in shares)		17,202
Options vested and exercisable weighted average remaining contractual life		8 years 3 months 18 days
Options vested and exercisable weighted average exercise price (in dollars per share)		$ 35.19
Options vested and exercisable intrinsic value		$ 7
$4.54 - 22.76
Range of exercise prices, lower range			$ 4.54
Range of exercise prices, upper range			$ 22.76
Number of shares vested and exercisable (in shares)			424,130
Options vested and exercisable weighted average remaining contractual life			4 years 4 months 9 days
Options vested and exercisable weighted average exercise price (in dollars per share)			$ 12.41
Options vested and exercisable intrinsic value			$ 10,303
$23.57 - 32.85
Range of exercise prices, lower range			$ 23.57
Range of exercise prices, upper range			$ 32.85
Number of shares vested and exercisable (in shares)			107,456
Options vested and exercisable weighted average remaining contractual life			8 years 3 months 21 days
Options vested and exercisable weighted average exercise price (in dollars per share)			$ 30.10
Options vested and exercisable intrinsic value			$ 709
$32.90 - 37.30
Range of exercise prices, lower range			$ 32.90
Range of exercise prices, upper range			$ 37.30
Number of shares vested and exercisable (in shares)			25,725
Options vested and exercisable weighted average remaining contractual life			9 years 2 months 8 days
Options vested and exercisable weighted average exercise price (in dollars per share)			$ 34.07
Options vested and exercisable intrinsic value			$ 68

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Shares
Outstanding, beginning of period (in shares) | shares	2,445,849
Granted (in shares) | shares	1,975,820
Exercised (in shares) | shares	(444,389)
Forfeited or Expired (in shares) | shares	(350,233)
Outstanding, end of period (in shares) | shares	3,627,047
Exercisable, end of period (in shares) | shares	538,949
Weighted Average Exercise Price
Outstanding, beginning of period (weighted average exercise price) | $ / shares	$ 30.77
Granted (weighted average exercise price) | $ / shares	41.50
Exercised (weighted average exercise price) | $ / shares	28.40
Forfeited or Expired (weighted average exercise price) | $ / shares	36.78
Outstanding, end of period (weighted average exercise price) | $ / shares	36.32
Exercisable, end of period (weighted average exercise price) | $ / shares	$ 25.58

Share-Based Compensation - Su_4

Share-Based Compensation - Summary of Unvested Restricted Stock Awards (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of period (in shares) | shares	292,450
Granted (in shares) | shares	113,018
Vested (in shares) | shares	(122,278)
Forfeited (in shares) | shares	(15,706)
Unvested, end of period (in shares) | shares	267,484
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested, beginning of period (weighted average grant date fair value) | $ / shares	$ 28.54
Granted (weighted average grant date fair value) | $ / shares	40.98
Vested (weighted average grant date fair value) | $ / shares	26.38
Forfeited (weighted average grant date fair value) | $ / shares	34.71
Unvested, end of period (weighted average grant date fair value) | $ / shares	$ 34.42

Share-Based Compensation - Su_5

Share-Based Compensation - Summary of Grant Date Fair Value of Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Options	$ 20,442	$ 12,932	$ 3,699
Restricted stock	4,631	3,609	4,217
Total	$ 25,073	$ 16,541	$ 7,916

Share-Based Compensation - Su_6

Share-Based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Options	$ 9,145	$ 5,344	$ 3,095
Restricted stock	2,654	2,518	3,218
Total	$ 11,799	$ 7,862	$ 6,313

Share-Based Compensation - Su_7

Share-Based Compensation - Summary of Income Tax Benefit Related to Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Options	$ 1,197	$ 980	$ 1,413
Restricted stock	575	353	1,051
Total	$ 1,772	$ 1,333	$ 2,464

Employee Benefits (Details)

Employee Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Definedcontributionemployeeautomaticcontributionpercentag	6.00%
Administrative expenses	$ 0	$ 0	$ 0
Contributions made to the defined contribution plan	$ 7,000,000	8,100,000	6,100,000
Profits sharing, percent of pre-tax profit paid to eligible employees on quarterly basis	10.00%
Employee profit sharing bonus plan	$ 7,400,000	6,200,000	8,400,000
Medical claim payments	5,900,000	5,900,000	4,800,000
Heath saving account payments	$ 3,300,000	$ 2,900,000	$ 2,500,000
Effective January 1, 2016
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of match	175.00%
Maximum annual contributions per employee, percent	6.00%

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($)	Nov. 08, 2018	May 18, 2018	Nov. 07, 2017	May 16, 2017	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Mar. 05, 2019	May 16, 2018	Jun. 02, 2016	May 19, 2015
Schedule of Shareholders' Equity [Line Items]
Authorized Repurchase														$ 20,000,000	$ 15,000,000	$ 25,000,000
Stock repurchased during period (in shares)								454,430	783,776	522,134			13,551,234
Aggregate price of shares repurchased since inception								$ 20,793,000	$ 27,943,000	$ 18,234,000			$ 209,315,000
Average price of shares repurchased since inception (per share)								$ 45.76	$ 35.65	$ 34.92			$ 15.45
Dividends declared (in dollars per share)					$ 0.16	$ 0.16	$ 0.16	$ 0.32	$ 0.32	$ 0.26
Cash dividends paid								$ 16,600,000	$ 16,700,000	$ 13,700,000
Regular Semi-Annual Dividend
Schedule of Shareholders' Equity [Line Items]
Dividends declared (in dollars per share)	$ 0.16	$ 0.16	$ 0.13	$ 0.13
Open market
Schedule of Shareholders' Equity [Line Items]
Stock repurchase program amount authorized (in shares)																	5,700,000
Stock repurchased during period (in shares)								5,799	252,272	8,676	4,101,566
Aggregate price of shares repurchased since inception								$ 200,000	$ 8,374,000	$ 284,000	$ 69,806,000
Average price of shares repurchased since inception (per share)								$ 34.46	$ 33.19	$ 32.69	$ 17.02
401(k)
Schedule of Shareholders' Equity [Line Items]
Stock repurchased during period (in shares)								419,963	497,753	467,580			7,467,739
Aggregate price of shares repurchased since inception								$ 19,386,000	$ 18,472,000	$ 16,336,000			$ 119,927,000
Average price of shares repurchased since inception (per share)								$ 46.16	$ 37.11	$ 34.94			$ 16.06
Directors & employees
Schedule of Shareholders' Equity [Line Items]
Stock repurchased during period (in shares)								28,668	33,751	45,878		1,981,929
Aggregate price of shares repurchased since inception								$ 1,207,000	$ 1,097,000	$ 1,614,000		$ 19,582,000
Average price of shares repurchased since inception (per share)								$ 42.11	$ 32.49	$ 35.19		$ 9.88

New Markets Tax Credit (Details

New Markets Tax Credit (Details) - USD ($)	Oct. 24, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Proceeds from financing obligation, net of issuance costs		$ 6,614,000	$ 0	$ 0
Due to affiliates		2	0
Debt issuance costs		7,000	$ 0	$ 0
Subsidiary
Line of Credit Facility [Line Items]
Due to affiliates	$ 22,500,000
Investor
Line of Credit Facility [Line Items]
Loans and leases receivable	$ 15,900,000
Loans and leases receivable, term	25 years
Loans and leases receivable, interest rate	1.00%
Proceeds from financing obligation, net of issuance costs	$ 15,900,000
Interest	6,300,000
Debt issuance costs	300,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility maximum borrowings	$ 23,000,000	$ 30,000,000

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2019USD ($)contract
Commitments and Contingencies Disclosure [Abstract]
Number of contracts | contract	1
Contractual obligation | $	$ 2.5

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 17,273	$ 14,290	$ 13,391	$ 8,757	$ 12,964	$ 14,514	$ 11,697	$ 3,154	$ 53,711	$ 42,329	$ 53,830
Basic weighted average shares (in shares)		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902	52,079,865	52,284,616	52,572,496
Effect of dilutive stock options and restricted stock									555,550	383,323	506,238
Diluted weighted average shares		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223	52,635,415	52,667,939	53,078,734
Basic (usd per share)	$ 0.33	$ 0.27	$ 0.26	$ 0.17	$ 0.25	$ 0.28	$ 0.22	$ 0.06	$ 1.03	$ 0.81	$ 1.02
Diluted (usd per share)	$ 0.33	$ 0.26	$ 0.26	$ 0.17	$ 0.25	$ 0.27	$ 0.22	$ 0.06	$ 1.02	$ 0.80	$ 1.01
Anti-dilutive shares (in shares)									1,868,087	1,920,313	785,825

Related Parties (Details)

Related Parties (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
Sales to affiliates	$ 886	$ 1,442	$ 1,579
Payments to affiliates	332	342	$ 432
Due from affiliates	22	79
Due to affiliates	$ 2	$ 0

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event $ in Millions	2 Months Ended
	Feb. 24, 2020USD ($)shares
Open Market
Subsequent Event [Line Items]
Stock repurchased during period (in shares) | shares	11,144
Stock repurchased during period | $	$ 0.6
401(k) Savings and Investment Plan
Subsequent Event [Line Items]
Stock repurchased during period (in shares) | shares	73,780
Stock repurchased during period | $	$ 3.9

Quarterly Results (Unaudited)_3

Quarterly Results (Unaudited) (As Corrected) (Quarterly Results) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 112,340	$ 112,937	$ 109,588	$ 99,082	$ 469,333	$ 433,947	$ 405,232
Gross profit	36,381	27,410	30,204	25,430	27,846	32,830	27,661	15,196	119,425	103,533	123,651
Net income	$ 17,273	$ 14,290	$ 13,391	$ 8,757	$ 12,964	$ 14,514	$ 11,697	$ 3,154	$ 53,711	$ 42,329	$ 53,830
Earnings per share:
Basic (usd per share)	$ 0.33	$ 0.27	$ 0.26	$ 0.17	$ 0.25	$ 0.28	$ 0.22	$ 0.06	$ 1.03	$ 0.81	$ 1.02
Diluted (usd per share)	$ 0.33	$ 0.26	$ 0.26	$ 0.17	$ 0.25	$ 0.27	$ 0.22	$ 0.06	$ 1.02	$ 0.80	$ 1.01

Quarterly Results (Unaudited)_4

Quarterly Results (Unaudited) (As Corrected) (Previously Reported Quarterly Results) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement Related Disclosures [Abstract]
Net sales	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 112,340	$ 112,937	$ 109,588	$ 99,082	$ 469,333	$ 433,947	$ 405,232
Cost of sales		86,090	89,233	88,392	84,494	80,107	81,927	83,886	349,908	330,414	281,581
Gross profit	36,381	27,410	30,204	25,430	27,846	32,830	27,661	15,196	119,425	103,533	123,651
Selling, general and administrative expenses		12,374	12,912	13,677	10,723	12,667	13,153	11,651	52,077	48,194	49,371
Loss (gain) on disposal of assets		6	6	284	(3)	2	(4)	(7)	337	(12)	45
Income from operations		15,030	17,286	11,469	17,126	20,161	14,512	3,552	67,011	55,351	74,235
Interest income, net		9	31	9	25	36	67	68	66	196	298
Other (expense) income, net		(7)	17	(26)	(58)	5	12	(6)	(46)	(47)	91
Income before taxes		15,032	17,334	11,452	17,093	20,202	14,591	3,614	67,031	55,500	74,624
Income tax provision		742	3,943	2,695	4,129	5,688	2,894	460	13,320	13,171	20,794
Net income	$ 17,273	$ 14,290	$ 13,391	$ 8,757	$ 12,964	$ 14,514	$ 11,697	$ 3,154	$ 53,711	$ 42,329	$ 53,830
Earnings per share:
Basic (usd per share)	$ 0.33	$ 0.27	$ 0.26	$ 0.17	$ 0.25	$ 0.28	$ 0.22	$ 0.06	$ 1.03	$ 0.81	$ 1.02
Diluted (usd per share)	$ 0.33	$ 0.26	0.26	$ 0.17	0.25	$ 0.27	0.22	$ 0.06	1.02	0.80	1.01
Cash dividends declared per common share (in dollars per share)			$ 0.16		$ 0.16		$ 0.16		$ 0.32	$ 0.32	$ 0.26
Weighted average shares outstanding:
Basic (in shares)		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902	52,079,865	52,284,616	52,572,496
Diluted (in shares)		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223	52,635,415	52,667,939	53,078,734
Balance Sheet Data (at end of period):
Current assets	$ 187,549	$ 170,284	$ 168,360	$ 146,511	$ 140,658	$ 144,476	$ 154,428	$ 154,450	$ 187,549	$ 140,658
Total assets	371,424	351,900	341,981	319,238	307,994	313,804	320,034	306,708	371,424	307,994
Current liabilities	56,028	53,103	58,102	43,082	47,491	53,071	70,962	56,581	56,028	47,491
Deferred tax liabilities	15,297	12,873	12,577	10,168	9,259	7,097	6,493	6,471	15,297	9,259
Other long-term liabilities	3,639	3,669	3,791	3,442	1,801	1,838	1,746	1,645	3,639	1,801
Total stockholders' equity	$ 290,140	282,255	267,511	262,546	249,443	251,798	240,833	242,011	$ 290,140	249,443	$ 238,925	$ 208,410
Previously Reported
Income Statement Related Disclosures [Abstract]
Net sales		113,500	119,437	113,822	112,340	112,937	109,588	99,082		433,947	405,232
Cost of sales		86,115	89,262	88,029	84,545	80,174	82,003	83,692		330,414	281,835
Gross profit		27,385	30,175	25,793	27,795	32,763	27,585	15,390		103,533	123,397
Selling, general and administrative expenses		12,994	13,481	11,001	11,260	13,190	13,086	10,219		47,755	49,249
Loss (gain) on disposal of assets		6	6	284	(3)	2	(4)	(7)		(12)	45
Income from operations		14,385	16,688	14,508	16,538	19,571	14,503	5,178		55,790	74,103
Interest income, net		9	31	9	25	36	67	68		196	298
Other (expense) income, net		(7)	17	(26)	(58)	5	12	(6)		(47)	91
Income before taxes		14,387	16,736	14,491	16,505	19,612	14,582	5,240		55,939	74,492
Income tax provision		560	3,775	3,589	3,969	5,527	2,891	980		13,367	19,994
Net income		$ 13,827	$ 12,961	$ 10,902	$ 12,536	$ 14,085	$ 11,691	$ 4,260		$ 42,572	$ 54,498
Earnings per share:
Basic (usd per share)		$ 0.27	$ 0.25	$ 0.21	$ 0.24	$ 0.27	$ 0.22	$ 0.08		$ 0.81	$ 1.04
Diluted (usd per share)		$ 0.26	0.25	$ 0.21	0.24	$ 0.27	0.22	$ 0.08		0.81	1.03
Cash dividends declared per common share (in dollars per share)			$ 0.16		$ 0.16		$ 0.16			$ 0.32	$ 0.26
Weighted average shares outstanding:
Basic (in shares)		52,111,444	52,120,272	51,992,150	52,086,247	52,238,796	52,383,842	52,433,902		52,284,616	52,572,496
Diluted (in shares)		52,722,127	52,474,199	52,369,660	52,420,529	52,627,541	52,717,787	52,910,223		52,667,939	53,078,734
Balance Sheet Data (at end of period):
Current assets		$ 170,536	$ 168,630	$ 146,798	$ 140,861	$ 144,696	$ 154,665	$ 154,687		$ 140,861
Total assets		352,152	342,251	319,525	308,197	314,024	320,271	306,945		308,197
Current liabilities		53,882	58,953	44,000	48,071	53,716	71,673	57,292		48,071
Deferred tax liabilities		15,034	14,938	12,713	10,826	8,841	8,415	8,397		10,826
Other long-term liabilities		3,669	3,791	3,442	1,801	1,838	1,746	1,645		1,801
Total stockholders' equity		279,567	264,569	259,370	247,499	249,629	238,437	239,611		247,499	$ 237,226	205,898
Corrections
Income Statement Related Disclosures [Abstract]
Net sales		0	0	0	0	0	0	0		0	0
Cost of sales		(25)	(29)	363	(51)	(67)	(76)	194		0	(254)
Gross profit		25	29	(363)	51	67	76	(194)		0	254
Selling, general and administrative expenses		(620)	(569)	2,676	(537)	(523)	67	1,432		439	122
Loss (gain) on disposal of assets		0	0	0	0	0	0	0		0	0
Income from operations		645	598	(3,039)	588	590	9	(1,626)		(439)	132
Interest income, net		0	0	0	0	0	0	0		0	0
Other (expense) income, net		0	0	0	0	0	0	0		0	0
Income before taxes		645	598	(3,039)	588	590	9	(1,626)		(439)	132
Income tax provision		182	168	(894)	160	161	3	(520)		(196)	800
Net income		$ 463	$ 430	$ (2,145)	$ 428	$ 429	$ 6	$ (1,106)		$ (243)	$ (668)
Earnings per share:
Basic (usd per share)		$ 0	$ 0.01	$ (0.04)	$ 0.01	$ 0.01	$ 0	$ (0.02)		$ 0	$ (0.02)
Diluted (usd per share)		$ 0	0.01	$ (0.04)	0.01	$ 0	0	$ (0.02)		(0.01)	(0.02)
Cash dividends declared per common share (in dollars per share)			$ 0		$ 0		$ 0			$ 0	$ 0
Weighted average shares outstanding:
Basic (in shares)		0	0	0	0	0	0	0		0	0
Diluted (in shares)		0	0	0	0	0	0	0		0	0
Balance Sheet Data (at end of period):
Current assets		$ (252)	$ (270)	$ (287)	$ (203)	$ (220)	$ (237)	$ (237)		$ (203)
Total assets		(252)	(270)	(287)	(203)	(220)	(237)	(237)		(203)
Current liabilities		(779)	(851)	(918)	(580)	(645)	(711)	(711)		(580)
Deferred tax liabilities		(2,161)	(2,361)	(2,545)	(1,567)	(1,744)	(1,922)	(1,926)		(1,567)
Other long-term liabilities		0	0	0	0	0	0	0		0
Total stockholders' equity		$ 2,688	$ 2,942	$ 3,176	$ 1,944	$ 2,169	$ 2,396	$ 2,400		$ 1,944	$ 1,699	$ 2,512

Quarterly Results (Unaudited)_5

Quarterly Results (Unaudited) (As Corrected) (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation								$ 11,799,000	$ 7,862,000	$ 6,313,000
Employee profit sharing bonus plan								$ 7,400,000	6,200,000	8,400,000
Corrections | Cost of Sales
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		0	300,000
Corrections | Selling, General and Administrative Expenses
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	700,000	600,000	3,000,000	(600,000)	(600,000)	100,000	1,600,000		500,000	100,000
Employee profit sharing bonus plan	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		$ 100,000	$ 100,000

Segments (Details)

Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 112,340	$ 112,937	$ 109,588	$ 99,082	$ 469,333	$ 433,947	$ 405,232
Gross profit	$ 36,381	$ 27,410	$ 30,204	$ 25,430	$ 27,846	$ 32,830	$ 27,661	$ 15,196	119,425	103,533	123,651
Operating Segments | Units
Segment Reporting Information [Line Items]
Net sales									434,283	406,331	384,853
Gross profit									121,878	108,214	128,647
Operating Segments | Parts
Segment Reporting Information [Line Items]
Net sales									35,424	28,456	22,050
Gross profit									17,301	13,215	9,555
Other
Segment Reporting Information [Line Items]
Net sales									(374)	(840)	(1,671)
Gross profit									(19,754)	(17,896)	(14,551)
Inter-segment
Segment Reporting Information [Line Items]
Net sales									28,053	29,385	29,293
Gross profit									$ 985	$ 865	$ 426