Advanced Energy Industries (AEIS) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 02, 2020
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2020
Entity File Number	000-26966
Entity Registrant Name	ADVANCED ENERGY INDUSTRIES INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-0846841
Entity Address, Address Line One	1595 Wynkoop Street, Suite 800
Entity Address, City or Town	Denver
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80202
City Area Code	970
Local Phone Number	407-6626
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AEIS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	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 Common Stock, Shares Outstanding		38,272,715
Entity Central Index Key	0000927003
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 428,977	$ 346,441
Marketable securities	2,601	2,614
Accounts and other receivable, net	240,147	246,564
Inventories	257,374	230,019
Income taxes receivable	13,042	4,245
Other current assets	36,335	36,855
Total current assets	978,476	866,738
Property and equipment, net	109,975	108,109
Operating lease right-of-use assets	108,810	105,404
Deposits and other assets	19,313	22,556
Goodwill	206,559	202,932
Intangible assets, net	169,250	184,011
Deferred income tax assets	50,136	42,656
TOTAL ASSETS	1,642,519	1,532,406
Current liabilities:
Accounts payable	159,332	170,671
Income taxes payable	14,074	9,687
Accrued payroll and employee benefits	67,757	51,545
Other accrued expenses	46,282	41,691
Customer deposits and other	14,332	10,926
Current portion of long-term debt	17,500	17,500
Current portion of operating lease liabilities	17,243	18,312
Total current liabilities	336,520	320,332
Long-term debt	308,794	321,527
Operating lease liabilities	97,604	90,538
Pension benefits	70,156	68,169
Deferred income tax liabilities	10,128	9,952
Uncertain tax positions	16,686	16,055
Long-term deferred revenue	7,357	8,011
Other long-term liabilities	26,541	20,562
Total liabilities	873,786	855,146
Commitments and contingencies (Note 19)
Stockholders' equity:
Preferred stock, $0.001 par value, 1,000 shares authorized, none issued and outstanding
Common stock, $0.001 par value, 70,000 shares authorized; 38,272 and 38,358 issued and outstanding at September 30, 2020 and December 31, 2019, respectively	38	38
Additional paid-in capital	101,485	104,849
Accumulated other comprehensive loss	(3,827)	(5,897)
Retained earnings	670,456	577,724
Advanced Energy stockholders' equity	768,152	676,714
Noncontrolling interest	581	546
Total stockholders' equity	768,733	677,260
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,642,519	$ 1,532,406

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,000	1,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	70,000,000	70,000,000
Common stock, shares issued (in shares)	38,272,000	38,358,000
Common stock, shares outstanding (in shares)	38,272,000	38,358,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Sales, net:
Total sales, net	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
Cost of sales:
Total cost of sales	235,736	101,636	648,537	247,323
Gross profit	153,785	73,491	396,320	203,357
Operating expenses:
Research and development	36,807	24,546	107,432	67,675
Selling, general and administrative	51,481	36,401	145,646	93,027
Amortization of intangible assets	5,049	3,002	15,064	6,849
Restructuring expense	1,494	152	7,940	3,620
Total operating expenses	94,831	64,101	276,082	171,171
Operating income	58,954	9,390	120,238	32,186
Other income (expense), net	(6,558)	1,361	(11,655)	17,649
Income from continuing operations, before income taxes	52,396	10,751	108,583	49,835
Provision for income taxes	6,783	3,495	15,293	3,819
Income from continuing operations	45,613	7,256	93,290	46,016
Income (loss) from discontinued operations, net of income taxes	50	375	(421)	8,690
Net income	45,663	7,631	92,869	54,706
Income from continuing operations attributable to noncontrolling interest	36	10	35	29
Net income attributable to Advanced Energy Industries, Inc.	$ 45,627	$ 7,621	$ 92,834	$ 54,677
Basic weighted-average common shares outstanding	38,325	38,313	38,322	38,258
Diluted weighted-average common shares outstanding	38,528	38,489	38,531	38,457
Earnings per share:
Continuing operations: Basic earnings per share	$ 1.19	$ 0.19	$ 2.43	$ 1.20
Continuing operations: Diluted earnings per share	1.18	0.19	2.42	1.20
Discontinued operations: Basic earnings (loss) per share		0.01	(0.01)	0.23
Discontinued operations: Diluted earnings (loss) per share		0.01	(0.01)	0.23
Net income:
Basic earnings per share	1.19	0.20	2.42	1.43
Diluted earnings per share	$ 1.19	$ 0.20	$ 2.41	$ 1.42
Product [Member]
Sales, net:
Total sales, net	$ 358,257	$ 148,138	$ 959,388	$ 366,443
Cost of sales:
Total cost of sales	220,149	87,536	606,750	204,450
Services [Member]
Sales, net:
Total sales, net	31,264	26,989	85,469	84,237
Cost of sales:
Total cost of sales	$ 15,587	$ 14,100	$ 41,787	$ 42,873

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements of Comprehensive Income
Net income	$ 45,663	$ 7,631	$ 92,869	$ 54,706
Other comprehensive income (loss), net of income taxes
Foreign currency translation	5,267	(4,849)	4,706	(6,281)
Change in fair value of cash flow hedges	170		(2,674)
Minimum benefit retirement liability	(116)	92	38	102
Comprehensive income	50,984	2,874	94,939	48,527
Comprehensive income attributable to noncontrolling interest	36	10	35	29
Comprehensive income attributable to Advanced Energy Industries, Inc.	$ 50,948	$ 2,864	$ 94,904	$ 48,498

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Retained Earnings	Non-controlling Interest	Total
Beginning Balance at Dec. 31, 2018	$ 38	$ 97,418	$ (3,449)	$ 512,783	$ 512	$ 607,302
Beginning Balance (in shares) at Dec. 31, 2018	38,164
Stock issued from equity plans		(1,707)				(1,707)
Stock issued from equity plans (in shares)	72
Stock-based compensation		3,199				3,199
Other comprehensive income (loss)			(2,028)			(2,028)
Net income				15,370	8	15,378
Ending Balance at Mar. 31, 2019	$ 38	98,910	(5,477)	528,153	520	622,144
Ending Balance (in shares) at Mar. 31, 2019	38,236
Beginning Balance at Dec. 31, 2018	$ 38	97,418	(3,449)	512,783	512	607,302
Beginning Balance (in shares) at Dec. 31, 2018	38,164
Net income						54,706
Ending Balance at Sep. 30, 2019	$ 38	101,757	(9,628)	567,460	541	660,168
Ending Balance (in shares) at Sep. 30, 2019	38,332
Beginning Balance at Mar. 31, 2019	$ 38	98,910	(5,477)	528,153	520	622,144
Beginning Balance (in shares) at Mar. 31, 2019	38,236
Stock issued from equity plans		665				665
Stock issued from equity plans (in shares)	69
Stock-based compensation		937				937
Other comprehensive income (loss)			606			606
Net income				31,686	11	31,697
Ending Balance at Jun. 30, 2019	$ 38	100,512	(4,871)	559,839	531	656,049
Ending Balance (in shares) at Jun. 30, 2019	38,305
Stock issued from equity plans		328				328
Stock issued from equity plans (in shares)	27
Stock-based compensation		917				917
Other comprehensive income (loss)			(4,757)			(4,757)
Net income				7,621	10	7,631
Ending Balance at Sep. 30, 2019	$ 38	101,757	(9,628)	567,460	541	660,168
Ending Balance (in shares) at Sep. 30, 2019	38,332
Adoption of new accounting standards				(102)		(102)
Beginning Balance at Dec. 31, 2019	$ 38	104,849	(5,897)	577,724	546	$ 677,260
Beginning Balance (in shares) at Dec. 31, 2019	38,358					38,358
Stock issued from equity plans		(2,171)				$ (2,171)
Stock issued from equity plans (in shares)	64
Stock-based compensation		3,048				3,048
Stock buyback		(7,248)				(7,248)
Stock buyback (in shares)	(170)
Other comprehensive income (loss)			(2,907)			(2,907)
Net income				18,063	15	18,078
Ending Balance at Mar. 31, 2020	$ 38	98,478	(8,804)	595,685	561	685,958
Ending Balance (in shares) at Mar. 31, 2020	38,252
Beginning Balance at Dec. 31, 2019	$ 38	104,849	(5,897)	577,724	546	$ 677,260
Beginning Balance (in shares) at Dec. 31, 2019	38,358					38,358
Stock buyback						$ (11,579)
Net income						92,869
Ending Balance at Sep. 30, 2020	$ 38	101,485	(3,827)	670,456	581	$ 768,733
Ending Balance (in shares) at Sep. 30, 2020	38,272					38,272
Beginning Balance at Mar. 31, 2020	$ 38	98,478	(8,804)	595,685	561	$ 685,958
Beginning Balance (in shares) at Mar. 31, 2020	38,252
Stock issued from equity plans		779				779
Stock issued from equity plans (in shares)	73
Stock-based compensation		2,837				2,837
Other comprehensive income (loss)			(344)			(344)
Net income				29,144	(16)	29,128
Ending Balance at Jun. 30, 2020	$ 38	102,094	(9,148)	624,829	545	718,358
Ending Balance (in shares) at Jun. 30, 2020	38,325
Stock issued from equity plans		(59)				(59)
Stock issued from equity plans (in shares)	20
Stock-based compensation		3,781				3,781
Stock buyback		(4,331)				(4,331)
Stock buyback (in shares)	(73)
Other comprehensive income (loss)			5,321			5,321
Net income				45,627	36	45,663
Ending Balance at Sep. 30, 2020	$ 38	$ 101,485	$ (3,827)	$ 670,456	$ 581	$ 768,733
Ending Balance (in shares) at Sep. 30, 2020	38,272					38,272

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 92,869	$ 54,706
Income (loss) from discontinued operations, net of income taxes	(421)	8,690
Income from continuing operations, net of income taxes	93,290	46,016
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	35,433	15,301
Stock-based compensation expense	9,666	5,053
Provision (benefit) for deferred income taxes	(7,849)	2,825
Gain on sale of central inverter service business		(14,804)
Discount on notes receivable	721
Net loss on disposal of assets	678	104
Changes in operating assets and liabilities, net of assets acquired:
Accounts and other receivable, net	8,670	(23,292)
Inventories	(26,983)	(7,217)
Other assets	5,039	13,695
Accounts payable	(12,971)	23,676
Other liabilities and accrued expenses	30,964	(17,779)
Income taxes	(1,626)	(14,720)
Net cash from operating activities from continuing operations	135,032	28,858
Net cash from operating activities from discontinued operations	(659)	317
Net cash from operating activities	134,373	29,175
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sale of marketable securities	3
Proceeds from sale of property and equipment	103	1,742
Acquisitions, net of cash acquired	(1,127)	(365,798)
Issuance of notes receivable	(1,000)	(2,800)
Purchases of property and equipment	(25,232)	(15,681)
Net cash from investing activities from continuing operations	(27,253)	(382,537)
Net cash from investing activities	(27,253)	(382,537)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from long-term borrowings		347,486
Payments on long-term borrowings	(13,125)	(4,375)
Purchase and retirement of common stock	(11,579)
Net payments related to stock-based award activities	(1,451)	(714)
Net cash from financing activities from continuing operations	(26,155)	342,397
Net cash from financing activities	(26,155)	342,397
EFFECT OF CURRENCY TRANSLATION ON CASH	1,571	(3,185)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	82,536	(14,150)
CASH AND CASH EQUIVALENTS, beginning of period	346,441	354,552
CASH AND CASH EQUIVALENTS, end of period	428,977	340,402
CASH AND CASH EQUIVALENTS FROM CONTINUING OPERATIONS, end of period	428,977	340,402
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	4,261	1,049
Cash paid for income taxes	16,079	15,372
Cash received for refunds of income taxes	$ 821	$ 1,537

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2020
BASIS OF PRESENTATION
BASIS OF PRESENTATION	NOTE 1. BASIS OF PRESENTATION ​ Advanced Energy Industries, Inc., a Delaware corporation, and its wholly-owned subsidiaries ("we," "us," "our," "Advanced Energy," or the "Company") design, manufacture, sell and support precision power products that transform, refine, and modify the raw electrical power from the utility and convert it into various types of highly-controllable usable power that is predictable, repeatable and customizable. Our power solutions enable innovation in complex semiconductor and thin film plasma processes such as dry etch, strip, chemical and physical deposition, high and low voltage applications such as process control, analytical instrumentation and medical equipment, and in temperature-critical thermal applications such as material and chemical processing. We also supply related instrumentation products for advanced temperature measurement and control, electrostatic instrumentation products for test and measurement applications, and gas sensing and monitoring solutions for several industrial markets. Our network of service support centers provides local repair and field service capability in key regions, provide upgrades and refurbishment services and sell used equipment to businesses that use our products. In September 2019, we acquired the Artesyn Embedded Power business, which added new power products and technologies used in networking and computing, data center including hyperscale, and industrial and medical applications. As of December 31, 2015, we discontinued our engineering, production, and sales of our Inverter product line. As such, all Inverter product revenues, costs, assets, and liabilities are reported in Discontinued Operations for all periods presented herein, and we currently report as a single unit. See Note 4. Disposed and Discontinued Operations In the opinion of management, the accompanying Unaudited Consolidated Financial Statements contain all adjustments, consisting of normal, recurring adjustments, necessary to present fairly the financial position of the Company as of September 30, 2020, and the results of our operations and cash flows for the three and nine months ended September 30, 2020 and 2019. The Unaudited Consolidated Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") have been omitted pursuant to such rules and regulations. These Unaudited Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto contained in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019 and other financial information filed with the SEC. Use of Estimates in the Preparation of the Consolidated Financial Statements The preparation of our Consolidated Financial Statements in conformity with U.S. GAAP requires us to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, and disclosure of contingent liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. We believe the significant estimates, assumptions, and judgments when accounting for items and matters such as allowances for expected credit loss, excess and obsolete inventory, warranty reserves, right-of-use assets and related operating lease liabilities, acquisitions, asset valuations, asset life, depreciation, amortization, recoverability of assets, impairments, deferred revenue, stock option and restricted stock grants, taxes, and other provisions are reasonable, based upon information available at the time they are made. Actual results may differ from these estimates, making it possible that a change in these estimates could occur in the near term. Critical Accounting Policies Derivatives The Company uses derivative financial instruments to manage risks associated with foreign currency and interest rate fluctuations. Unless we meet specific hedge accounting criteria, changes in the fair value of derivative financial instruments are recognized in the Consolidated Statements of Operations within Other income (expense), net. For derivatives designated as cash flow hedges, changes in fair value are recorded to Accumulated other comprehensive income (loss) on the Consolidated Balance Sheets and are reclassified to earnings when the underlying forecasted transaction affects earnings. We reassess the probability of the underlying forecasted transactions occurring on a quarterly basis. Fair Value We value our financial assets and liabilities using fair value measurements. U.S. GAAP for fair value establishes a hierarchy that prioritizes fair value measurements based on the types of inputs used for the various valuation techniques (market approach, income approach, and cost approach). The Company’s financial assets and liabilities are measured using inputs from the three levels of the fair value hierarchy. The three levels of the hierarchy and the related inputs are as follows: ● Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities that the entity can access at the measurement date. ● Level 2 — Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ● Level 3 — Unobservable inputs for the asset or liability. The Company categorizes fair value measurements within the fair value hierarchy based upon the lowest level of the most significant inputs used to determine fair value. Our assessment of the significance of a particular input to the fair value measurement requires judgement and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels. The carrying amounts of our cash and cash equivalents, accounts receivable, accounts payable and other current assets and liabilities approximate fair value as recorded due to the short-term nature of these instruments. The Company’s non-financial assets, which primarily consist of property and equipment, goodwill, and other intangible assets, are not required to be carried at fair value on a recurring basis and are reported at carrying value. However, on a periodic basis or whenever events or changes in circumstances indicate that their carrying value may not be fully recoverable (and at least annually for goodwill and indefinite-lived intangible assets), non-financial instruments are assessed for impairment and, if applicable, written down to and recorded at fair value. See Note 12, Goodwill, Note 13, Intangible Assets, The fair value of borrowings approximates the recorded borrowing value based upon market interest rates for similar facilities. See Note 22, Credit Facility New Accounting Standards From time to time, the Financial Accounting Standards Board ("FASB") or other standards setting bodies issue new accounting pronouncements. Updates to the FASB Accounting Standards Codification ("ASC") are communicated through issuance of an Accounting Standards Update ("ASU"). Unless otherwise discussed, we believe that the impact of recently issued guidance, whether adopted or to be adopted in the future, is not expected to have a material impact on the Consolidated Financial Statements upon adoption. Recently issued accounting pronouncements not yet adopted In August 2018, the FASB issued ASU 2018-14, "Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20)" ("ASU 2018-14"). ASU 2018-14 eliminates requirements for certain disclosures and requires additional disclosures under defined benefit pension plans and other post-retirement plans. ASU 2018-14 is effective for fiscal years ending after December 15, 2020 and shall be applied to all periods presented on a retrospective basis. Early adoption is permitted. We are currently assessing and do not believe ASU 2018-14 will have a significant impact on our defined benefit plan disclosure requirements. In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (“ASU 2020-04”). ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another rate that is expected to be discontinued. ASU 2020-04 will be in effect through December 31, 2022. We are currently assessing the potential impact of ASU 2020-04 on our Consolidated Financial Statements. Recently adopted accounting pronouncements In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses (Topic 326)" The Company’s principal customers are original equipment manufacturers and end user customers, which operate globally through wholly owned subsidiaries that purchase the Company’s products under substantially the same credit terms, with similar historical credit risks. As a result, the Company assesses credit risks for its customers as a single group. The Company evaluates collection risk and establishes its expected credit loss primarily through a combination of the following: an assessment of customer credit risk ratings utilizing third party credit risk data, analysis of historical aging and credit loss experience, and customer specific information. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820)" In December 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes" ​

BUSINESS ACQUISITIONS

BUSINESS ACQUISITIONS	9 Months Ended
	Sep. 30, 2020
BUSINESS ACQUISITIONS
BUSINESS ACQUISITIONS	NOTE 2. BUSINESS ACQUISITIONS Artesyn’s Embedded Power Business In September 2019, we completed the acquisition of Artesyn Embedded Technologies, Inc.’s (“Artesyn”) Embedded Power business pursuant to the Stock Purchase Agreement, dated May 14, 2019 as amended (the “Acquisition Agreement”). Pursuant to the Acquisition Agreement, we acquired all of Artesyn’s issued and outstanding shares for a purchase price of $370.2 million including the assumption of certain liabilities and the finalization of the net working capital adjustment. In connection with the Acquisition Agreement, we entered into a credit agreement that provided us with aggregate financing of $500.0 million which was used to partially fund the Artesyn acquisition. Note 22. Credit Facility for additional details related to the credit agreement. Artesyn’s Embedded Power business is one of the world’s largest providers of highly engineered, application-specific power supplies for demanding applications. This acquisition diversified our product portfolio and gave us access to additional growth markets, including data centers and hyperscale, telecom infrastructure in next generation 5G networks, embedded industrial power applications and medical power for diagnostic and treatment applications. The components of the fair value of the total consideration transferred for the acquisition is as follows: ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for acquisition ​ $ 390,453 Contingent consideration ​ ​ 3,008 Total fair value of consideration transferred ​ ​ 393,461 Less cash acquired ​ (23,225) Total purchase price ​ $ 370,236 ​ The following table summarizes the final fair values of the assets acquired and liabilities assumed from the acquisition, along with the measurement period adjustments that occurred during the quarter: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Preliminary Measurement Final Fair Accounts and other receivable, net ​ $ 132,466 ​ $ — ​ $ 132,466 Inventories ​ 156,407 ​ ​ — ​ ​ 156,407 Property and equipment ​ 63,321 ​ ​ — ​ ​ 63,321 Operating lease right-of-use assets ​ ​ 54,439 ​ ​ — ​ ​ 54,439 Goodwill ​ 117,762 ​ ​ (2,764) ​ ​ 114,998 Intangible assets ​ 124,000 ​ ​ — ​ ​ 124,000 Other assets ​ 63,863 ​ ​ (649) ​ ​ 63,214 Total assets acquired ​ 712,258 ​ ​ (3,413) ​ ​ 708,845 Accounts payable ​ 152,635 ​ ​ — ​ ​ 152,635 Operating lease liability ​ ​ 54,515 ​ ​ — ​ ​ 54,515 Pension liability ​ ​ 48,315 ​ ​ — ​ ​ 48,315 Deferred income tax liabilities ​ 5,870 ​ ​ (4,175) ​ ​ 1,695 Other liabilities ​ 86,648 ​ ​ (5,199) ​ ​ 81,449 Total liabilities assumed ​ 347,983 ​ ​ (9,374) ​ ​ 338,609 Total fair value of net assets acquired ​ $ 364,275 ​ $ 5,961 ​ $ 370,236 ​ A summary of the intangible assets acquired, amortization method and estimated useful lives are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization ​ ​ ​ ​ ​ ​ ​ Method ​ Useful Life ​ Technology ​ $ 28,000 Straight-line 5 ​ Customer relationships ​ 75,000 Straight-line 15 ​ Tradename ​ 21,000 Straight-line 10 ​ Total ​ $ 124,000 ​ ​ Goodwill and intangible assets are recorded in the functional currency of the entity and are subject to changes due to translation at each balance sheet date. The goodwill represents expected operating synergies from combining operations with the acquired company and the estimated value associated with the enhancements to our comprehensive product lines and access to new markets. During the quarter, Advanced Energy settled the adjustment for net working capital and finalized the fair value for the assets acquired and liabilities assumed related to the Artesyn acquisition. Accordingly, the purchase price allocation presented above is final. ​ Pro forma results for Advanced Energy Inc. giving effect to the Artesyn Embedded Power Business Transactions The following unaudited pro forma financial information presents the combined results of operations of Advanced Energy and Artesyn as if the acquisition had been completed at the beginning of fiscal year 2019. The unaudited pro forma financial information is presented for informational purposes and is not indicative of the results of operations that would have been achieved if the acquisitions had taken place at the beginning of the year prior to the acquisition dates, nor are they indicative of future results. ​ The unaudited pro forma financial information for the three and nine months ended September 30, 2019 combines Advanced Energy’s results with the pre-acquisition results of Artesyn for that period. The following tables present our unaudited pro forma results for the acquisition of Artesyn: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2019 ​ 2019 ​ As Reported Pro Forma As Reported Pro Forma Total sales $ 175,127 $ 293,658 $ 450,680 $ 864,522 Net income attributable to Advanced Energy Industries, Inc. $ 7,621 $ 12,577 $ 54,677 $ 54,622 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ Basic earnings per share ​ $ 0.20 ​ $ 0.33 ​ $ 1.43 ​ $ 1.43 Diluted earnings per share ​ $ 0.20 ​ $ 0.33 ​ $ 1.42 ​ $ 1.42 ​ The unaudited pro forma results for all periods presented include adjustments made to account for certain costs and transactions that would have been incurred had the acquisitions been completed at the beginning of the year prior to the year of acquisition. These include adjustments to amortization charges for acquired intangible assets, interest and financing expenses, transaction costs, amortization of purchased gross profit and the alignment of various accounting policies. These adjustments are net of any applicable tax impact and were included to arrive at the pro forma results above. Artesyn’s operating results have been included in the Advanced Energy’s operating results for the periods after the completion of the acquisition on September 10, 2019. Artesyn contributed total sales of $188.8 million and net income of $14.9 million for the three months ended September 30, 2020, and $502.5 million in total sales and net income of $23.5 million for the nine months ended September 30, 2020.

REVENUE

REVENUE	9 Months Ended
	Sep. 30, 2020
REVENUE
REVENUE	NOTE 3. REVENUE Revenue Recognition We recognize revenue when we have satisfied our performance obligations which typically occurs when control of the products or services has been transferred to our customers. The transaction price is based upon the standalone selling price. In most transactions, we have no obligations to our customers after the date products are shipped, other than pursuant to warranty obligations. Shipping and handling fees billed to customers, if any, are recognized as revenue. The related shipping and handling costs are recognized in cost of sales. Support services include warranty and non-warranty repair services, upgrades, and refurbishments on the products we sell. Repairs that are covered under our standard warranty do not generate revenue. Practical Expedients We expense incremental costs of obtaining contracts when the amortization period of the costs is less than one year. These costs are included in selling, general, and administrative expenses. Nature of goods and services Products Advanced Energy provides highly engineered, mission-critical, precision power conversion, measurement, and control solutions to our global customers. We design, manufacture, sell and support precision power products that transform electrical power into various usable forms. Our power conversion products refine, modify, and control the raw electrical power from a utility and convert it into power that is predictable, repeatable and customizable. Our products enable thin film manufacturing processes such as plasma enhanced chemical and physical deposition and etch for various semiconductor and industrial products, industrial thermal applications for material and chemical processes, and specialty power for critical industrial technology applications. We also supply thermal instrumentation products for advanced temperature measurement and control in these markets. As a result of the Artesyn acquisition, we now sell precision power conversion products into the telecom and networking, data center, including hyperscale, and new medical and industrial markets. Our products are designed to enable new process technologies, improve productivity, and lower the cost of ownership for our customers. We also provide repair and maintenance services for all our products. We principally serve original equipment manufacturers ("OEM") and end customers in the semiconductor, flat panel display, high voltage, solar panel, telecom and networking, data center, medical, and other industrial capital equipment markets. Our advanced power products are used in diverse markets, applications, and processes including the manufacture of capital equipment for semiconductor device manufacturing, thin film applications for thin film renewables and architectural glass, and for other thin film applications including flat panel displays, and industrial coatings. Our embedded power products are used in a wide range of applications, including 5G, datacenter including hyperscale and other industrial and medical applications. Services Our services group offers warranty and after-market repair services in the regions in which we operate, providing us with preventive maintenance opportunities. Our customers continue to pursue low cost of ownership of their capital equipment and are increasingly sensitive to the costs of system downtime. They expect that suppliers offer comprehensive local repair service and customer support. To meet these market requirements, we maintain a worldwide support organization comprising both direct and indirect activities, through partnership with local distributors, primarily in the United States ("U.S."), the People’s Republic of China ("PRC"), Japan, South Korea, Taiwan, Malaysia, Israel, Philippines, Germany, Singapore and United Kingdom. As part of our ongoing service business, we satisfy our service obligations under preventative maintenance contracts and extended warranties which had previously been offered on our discontinued inverter products. Any up-front fees received for extended warranties or maintenance plans are deferred. Revenue under these arrangements is recognized ratably over the underlying terms as we do not have historical information which would allow us to project the estimated service usage pattern at this time. In May 2019, we sold our grid-tied central inverter repair and service operation to a third party. In connection with this sale, approximately $22.0 million of deferred revenue related to extended warranties and service contracts were transferred to the buyer. See Note 4. Disposed and Discontinued Operations Disaggregation of Revenue The following table presents our sales by product line, inclusive of both products and services, which includes certain reclassification to prior comparative periods to conform to our current year presentation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Semiconductor Equipment ​ $ 167,058 ​ $ 96,426 ​ $ 446,107 ​ $ 277,911 ​ Industrial & Medical ​ 87,013 ​ 55,187 ​ 219,877 ​ 149,255 ​ Data Center Computing ​ ​ 87,741 ​ ​ 13,498 ​ ​ 257,240 ​ ​ 13,498 ​ Telecom & Networking ​ ​ 47,709 ​ ​ 10,016 ​ ​ 121,633 ​ ​ 10,016 ​ Total ​ $ 389,521 ​ $ 175,127 ​ $ 1,044,857 ​ $ 450,680 ​ ​ The following table presents our sales by geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 ​ 2019 2020 ​ 2019 North America ​ $ 190,629 $ 83,632 ​ $ 504,719 $ 203,531 Asia ​ 180,660 ​ 66,157 ​ ​ 462,388 ​ 175,554 Europe ​ 17,886 ​ 25,008 ​ ​ 76,070 ​ 70,526 Other ​ 346 ​ 330 ​ ​ 1,680 ​ 1,069 Total ​ $ 389,521 $ 175,127 ​ $ 1,044,857 $ 450,680 ​ The following table presents our net sales by extended warranty and service contracts recognized over time and our product and service revenue recognized at a point in time: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Product and service revenue recognized at point in time ​ $ 389,306 ​ $ 174,827 ​ $ 1,044,255 ​ $ 448,964 ​ Extended warranty and service contracts recognized over time ​ 215 ​ 300 ​ 602 ​ 1,716 ​ Total ​ $ 389,521 ​ $ 175,127 ​ $ 1,044,857 ​ $ 450,680 ​ ​

DISPOSED AND DISCONTINUED OPERA

DISPOSED AND DISCONTINUED OPERATIONS	9 Months Ended
	Sep. 30, 2020
DISPOSED AND DISCONTINUED OPERATIONS
DISPOSED AND DISCONTINUED OPERATIONS	NOTE 4. DISPOSED AND DISCONTINUED OPERATIONS Disposed Operations In May 2019, we sold our grid-tied central solar inverter services business to Bold Renewables Holdings, LLC (“Bold”) for $1.00 dollar and the assumption by Bold of our initial product warranty and our extended warranty service obligations. In connection with this transaction, we entered into a Loan and Security Agreement with Bold (the “Loan and Security Agreement”). Under the Loan and Security Agreement, we loaned Bold an aggregate $5.3 million between May 2019 and the first quarter of 2020. Under the terms of the Loan and Security Agreement and for the next ten years, we have made an additional $2.75 million available for borrowing, subject to the satisfaction of certain operating and liquidity covenants by Bold. The borrowings under the Loan and Security Agreement bear interest at 0% for the first seven years and 5% thereafter. Additionally, the Loan and Security Agreement provides for early payment discounts of 50% during the first three years, 45% for years four and five and 40% thereafter up to 30 days prior to the maturity of the Loan and Security Agreement. A discount of $2.3 million has been recognized as a reduction to our gain recognized on the sale. As a result of the transaction, we reduced our discontinued operations liabilities by approximately $10.9 million that were related to initial product warranty and reduced our other liabilities by approximately $22.0 million that were related to extended warranty service obligations as well as reduced other assets and liabilities associated with the continuing grid-tied central solar inverter service and repair business. Accordingly, a $14.8 million non-cash gain was recognized in Other income (expense) from continuing operations and an $8.6 million non-cash gain, net of tax expense of $2.4 million, was recognized in “Income (loss) from discontinued operations”. Discontinued Operations In December 2015, we completed the wind down of engineering, manufacturing, and sales of our solar inverter product line (the "inverter business"). Accordingly, the results of our inverter business have been reflected as "Income (loss) from discontinued operations, net of income taxes" on our Consolidated Statements of Operations for all periods presented herein. The effect of our sales of extended inverter warranties to our customers continues to be reflected in deferred revenue in our Consolidated Balance Sheets. Deferred revenue for extended inverter warranties and the associated costs of warranty service will be reflected in Sales and Cost of goods sold, respectively, from continuing operations in future periods in our Consolidated Statement of Operations, as the deferred revenue, is earned and the associated services are rendered. Extended warranties related to the inverter product line are no longer offered. The significant items included in "Income (loss) from discontinued operations, net of income taxes" are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Sales ​ $ — ​ $ — ​ $ — ​ $ — ​ Cost of sales ​ — ​ (700) ​ — ​ (900) ​ Total operating expense ​ 128 ​ 133 ​ 533 ​ 514 ​ Operating income (loss) from discontinued operations ​ (128) ​ 567 ​ (533) ​ 386 ​ Other income (expense) ​ 151 ​ (84) ​ (1) ​ 10,835 ​ Income (loss) from discontinued operations before income taxes ​ 23 ​ 483 ​ (534) ​ 11,221 ​ Provision (benefit) for income taxes ​ (27) ​ 108 ​ (113) ​ 2,531 ​ Income (loss) from discontinued operations, net of income taxes ​ $ 50 ​ $ 375 ​ $ (421) ​ $ 8,690 ​ ​ Assets and Liabilities of discontinued operations within the Consolidated Balance Sheets are comprised of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Cash and cash equivalents $ — $ — Accounts and other receivables, net ​ ​ — ​ ​ — Inventories ​ ​ 23 ​ ​ 30 Other current assets ​ ​ 23 ​ ​ 30 Other assets ​ ​ — ​ ​ — Deferred income tax assets ​ 269 ​ 269 Deposits and other assets ​ ​ 269 ​ ​ 269 Accounts payable and other accrued expenses ​ ​ 137 ​ ​ — Accrued warranty ​ 894 ​ 914 Other accrued expenses ​ ​ 1,031 ​ ​ 914 Accrued warranty ​ ​ 310 ​ ​ 698 Other liabilities ​ 215 ​ 189 Other long-term liabilities ​ $ 525 ​ $ 887 ​

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2020
INCOME TAXES
INCOME TAXES	NOTE 5. INCOME TAXES The following table sets out the tax expense and the effective tax rate for our income from continuing operations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Income from continuing operations, before income taxes ​ $ 52,396 ​ $ 10,751 ​ $ 108,583 ​ $ 49,835 ​ Provision for income taxes ​ $ 6,783 ​ $ 3,495 ​ $ 15,293 ​ $ 3,819 ​ Effective tax rate ​ ​ 12.9 % ​ 32.5 % ​ 14.1 % ​ 7.7 % ​ Our effective tax rates differ from the U.S. federal statutory rate of 21% for the three and nine months ended September 30, 2020 and 2019, respectively, primarily due to the benefit of earnings in foreign jurisdictions which are subject to lower tax rates, partially offset by additional global intangible low-taxed income tax (“GILTI”) in the U.S. The effective tax rate for the first nine months of 2020 was higher than the same period in 2019 primarily due to the absence of a favorable discrete tax item in 2019 related to the release of liabilities for uncertain tax positions in the first quarter of 2019. The lower effective tax rate in the three months ended September 30, 2020 was primarily due to the absence of unfavorable discrete tax items in 2019 related to the Artesyn acquisition and a change in the indefinite reinvestment assertion.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2020
EARNINGS PER SHARE
EARNINGS PER SHARE	NOTE 6. EARNINGS PER SHARE Basic earnings per share ("EPS") is computed by dividing income available to common stockholders by the weighted-average number of common shares outstanding during the period. The computation of our diluted EPS is similar to the computation of our basic EPS except that the denominator is increased to include the number of additional common shares that would have been outstanding (using the if-converted and treasury stock methods), if our outstanding stock options and restricted stock units had been converted to common shares, and if such assumed conversion is dilutive. The following is a reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted EPS: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Income from continuing operations ​ $ 45,613 ​ $ 7,256 ​ $ 93,290 ​ $ 46,016 ​ Income from continuing operations attributable to noncontrolling interest ​ 36 ​ 10 ​ 35 ​ 29 ​ Income from continuing operations attributable to Advanced Energy Industries, Inc. ​ $ 45,577 ​ $ 7,246 ​ $ 93,255 ​ $ 45,987 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted-average common shares outstanding ​ 38,325 ​ 38,313 ​ 38,322 ​ 38,258 ​ Assumed exercise of dilutive stock options and restricted stock units ​ 203 ​ 176 ​ 209 ​ 199 ​ Diluted weighted-average common shares outstanding ​ 38,528 ​ 38,489 ​ 38,531 ​ 38,457 ​ Continuing operations: ​ ​ ​ ​ ​ Basic earnings per share ​ $ 1.19 ​ $ 0.19 ​ $ 2.43 ​ $ 1.20 ​ Diluted earnings per share ​ $ 1.18 ​ $ 0.19 ​ $ 2.42 ​ $ 1.20 ​ ​ The following restricted stock units were excluded in the computation of diluted earnings per share because they were anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Restricted stock units — 4 — 1 ​ Stock Buyback In September 2015, our Board of Directors authorized a program to repurchase up to $150.0 million of our stock over a thirty-month period. In November 2017, our Board of Directors approved an extension of the share repurchase program to December 2019 from its original maturity of March 2018. In May 2018, our Board of Directors approved a $50 million increase in its authorization to repurchase shares of Company common stock under this same program. On December 18, 2019, our Board of Directors authorized the removal of the expiration date to the Company’s share repurchase program and increased the authorized amount by $25.1 million. As of September 30, 2020, the Company had $38.4 million authorized for the future repurchase of shares of our common stock. In order to execute the repurchase of shares of our common stock, the Company periodically enters into stock repurchase agreements. The Company has repurchased the following shares of common stock: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ (in thousands, except per share amounts) 2020 2019 2020 2019 ​ Amount paid to repurchase shares ​ $ 4,331 ​ $ — ​ $ 11,579 ​ $ — ​ Number of shares repurchased ​ 73 ​ — ​ 243 ​ — ​ Average repurchase price per share ​ $ 59.70 ​ $ — ​ $ 47.70 ​ $ — ​ ​ There were no shares repurchased from related parties. All shares repurchased were recognized as a reduction to Additional paid-in capital. Repurchased shares were retired and assumed the status of authorized and unissued shares.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2020
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	NOTE 7. FAIR VALUE MEASUREMENTS The following tables present information about the Company’s assets and liabilities measured at fair value on a recurring basis. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 Description ​ Balance Sheet Classification ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ — ​ $ 2,601 ​ $ — ​ $ 2,601 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,601 ​ $ — ​ $ 2,601 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other long-term liabilities ​ $ — ​ $ — ​ $ 3,359 ​ $ 3,359 Interest rate swaps ​ Other long-term liabilities ​ ​ — ​ ​ 3,466 ​ ​ — ​ ​ 3,466 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 3,466 ​ $ 3,359 ​ $ 6,825 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 Description ​ Balance Sheet Classification ​ Level 1 Level 2 Level 3 Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ ​ ​ $ 2,614 ​ $ — ​ $ 2,614 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,614 ​ $ — ​ $ 2,614 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other long-term liabilities ​ $ — ​ $ — ​ $ 1,377 ​ $ 1,377 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ — ​ $ 1,377 ​ $ 1,377 ​ We determine the fair value of interest rate swaps by estimating the net present value of the expected cash flows based on market rates and associated yield curves, adjusted for non-performance credit risk, as applicable. See Note 8, Derivative Financial Instruments For all periods presented, there were no transfers into or out of Level 3

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2020
DERIVATIVE FINANCIAL INSTRUMENTS
DERIVATIVE FINANCIAL INSTRUMENTS	NOTE 8. DERIVATIVE FINANCIAL INSTRUMENTS We are impacted by changes in foreign currency exchange rates. We may manage these risks through the use of derivative financial instruments, primarily forward contracts with banks. These forward contracts manage the exchange rate risk associated with assets and liabilities denominated in nonfunctional currencies. These derivative instruments are not designated as hedges; however, they do offset the fluctuations of our assets and liabilities due to foreign exchange rate changes. These forward contracts are typically for one-month periods. As of September 30, 2020, and December 31, 2019, we did not have any currency exchange rate contracts outstanding. During the three and nine months ended September 30, 2020 and 2019 gains and losses related to foreign currency exchange contracts were offset by corresponding gains and losses on the revaluation of the underlying assets and liabilities. Both are included as a component of Other income (expense), net, in our Unaudited Consolidated Statements of Operations. In April 2020, the Company executed interest rate swap contracts with independent financial institutions to partially reduce the variability of cash flows in LIBOR indexed debt interest payments on our Term Loan Facility (under the Company’s existing Credit Agreement dated as of September 10, 2019). These transactions are accounted for as cash flow hedging instruments. The interest rate swap contracts fixed 85% of the outstanding principal balance on our term loan to a total interest rate of 1.271%. This is comprised of 0.521% average fixed rate per annum in exchange for a variable interest rate based on one-month USD-LIBOR-BBA plus the credit spread in the Company’s existing Credit Agreement, which is 75 basis points at current leverage ratios. The following table summarizes the notional amount of the Company’s qualified hedging instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Interest rate swap contracts ​ $ 277,594 ​ $ — ​ At September 30, 2020, Accumulated other comprehensive loss on the unaudited consolidated balance sheet includes $2.7 million, net of tax, related to changes in fair value on the interest rate swap contracts. The following table summarizes activity related to qualified hedging instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Gain (loss) recognized in Other comprehensive income (loss), net of tax ​ $ 170 ​ $ — ​ $ (2,674) ​ $ — ​ See Note 7. Fair Value Measurements As a result of the use of derivative financial instruments, the Company is exposed to the risk that counterparties to derivative contracts may fail to meet their contractual obligations. The Company manages counterparty credit risk in derivative contracts by reviewing counterparty creditworthiness on a regular basis and limiting exposure to any single counterparty.

ACCOUNTS AND OTHER RECEIVABLE

ACCOUNTS AND OTHER RECEIVABLE	9 Months Ended
	Sep. 30, 2020
ACCOUNTS AND OTHER RECEIVABLE
ACCOUNTS AND OTHER RECEIVABLE	NOTE 9. ACCOUNTS AND OTHER RECEIVABLE Accounts and other receivable are recorded at net realizable value. Components of accounts and other receivable, net of reserves, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Amounts billed, net ​ $ 221,447 ​ $ 227,528 Unbilled receivables ​ ​ 18,700 ​ 19,036 Total receivables, net ​ $ 240,147 ​ $ 246,564 ​ Amounts billed, net consist of amounts that have been invoiced to our customers in accordance with terms and conditions and are shown net of an allowance for credit losses. These receivables are all short-term in nature and do not include any financing components. Unbilled receivables consist of amounts where we have satisfied our contractual obligations related to inventory stocking contracts with customers. Such amounts typically become billable to the customer upon their consumption of the inventory managed under the stocking contracts. We anticipate that substantially all unbilled receivables will be invoiced and collected over the next twelve months. These contracts do not include any financing components. ​ The following table summarizes the changes in expected credit losses: ​ ​ ​ ​ ​ December 31, 2019 $ 7,745 Additions ​ 407 Deductions - write-offs, net of recoveries ​ (482) September 30, 2020 ​ $ 7,670 ​

INVENTORIES

INVENTORIES	9 Months Ended
	Sep. 30, 2020
INVENTORIES
INVENTORIES	NOTE 10. INVENTORIES Our inventories are valued at the lower of cost or net realizable value and computed on a first-in, first-out (FIFO) basis. Components of inventories are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 ​ Parts and raw materials ​ $ 155,217 ​ $ 134,816 ​ Work in process ​ 17,147 ​ 10,269 ​ Finished goods ​ 85,010 ​ 84,934 ​ Total ​ $ 257,374 ​ $ 230,019 ​ ​

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2020
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	NOTE 11. PROPERTY AND EQUIPMENT Property and equipment, net is comprised of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 ​ Buildings and land ​ $ 1,654 ​ $ 1,693 ​ Machinery and equipment ​ 107,038 ​ 108,945 ​ Computer and communication equipment ​ 25,258 ​ 29,106 ​ Furniture and fixtures ​ 4,203 ​ 4,119 ​ Vehicles ​ 261 ​ 262 ​ Leasehold improvements ​ 41,590 ​ 33,041 ​ Construction in process ​ 12,259 ​ 9,089 ​ ​ ​ 192,263 ​ 186,255 ​ Less: Accumulated depreciation ​ (82,288) ​ (78,146) ​ Property and equipment, net ​ $ 109,975 ​ $ 108,109 ​ ​ Depreciation expense is recorded in continuing operations and allocated within Cost of sales, Research and development expense and Selling, general and administrative expense in our Unaudited Consolidated Statements of Operations as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Depreciation expense ​ $ 7,188 ​ $ 3,903 ​ $ 20,369 ​ $ 8,452 ​ ​

GOODWILL

GOODWILL	9 Months Ended
	Sep. 30, 2020
GOODWILL AND INTANGIBLE ASSETS
GOODWILL	NOTE 12. GOODWILL The following table summarizes the changes in goodwill: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 $ 202,932 Measurement period adjustments to purchase price allocation ​ ​ 1,957 Foreign currency translation ​ ​ 1,670 September 30, 2020 ​ $ 206,559 ​

INTANGIBLE ASSETS

INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2020
GOODWILL AND INTANGIBLE ASSETS
INTANGIBLE ASSETS	NOTE 13. INTANGIBLE ASSETS Intangible assets consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying September 30, 2020 ​ Amount ​ Amortization ​ Amount Technology ​ $ 83,882 ​ $ (22,012) ​ $ 61,870 Customer relationships ​ 109,514 ​ (24,302) ​ 85,212 Trademarks and other ​ 26,892 ​ (4,724) ​ 22,168 Total ​ $ 220,288 ​ $ (51,038) ​ $ 169,250 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying December 31, 2019 ​ Amount ​ Amortization ​ Amount Technology ​ $ 83,368 ​ $ (14,250) ​ $ 69,118 Customer relationships ​ 108,995 ​ (18,197) ​ 90,798 Trademarks and other ​ 26,888 ​ (2,793) ​ 24,095 Total ​ $ 219,251 ​ $ (35,240) ​ $ 184,011 ​ Amortization expense related to intangible assets is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Amortization expense ​ $ 5,049 ​ $ 3,002 ​ $ 15,064 ​ $ 6,849 ​ ​ Estimated amortization expense related to intangibles is as follows: ​ ​ ​ ​ ​ Year Ending December 31, ​ ​ 2020 (remaining) ​ $ 5,049 2021 ​ 20,093 2022 ​ 19,815 2023 ​ 19,796 2024 ​ 16,926 Thereafter ​ 87,571 Total ​ $ 169,250 ​

RESTRUCTURING COSTS

RESTRUCTURING COSTS	9 Months Ended
	Sep. 30, 2020
RESTRUCTURING COSTS
RESTRUCTURING COSTS	NOTE 14. RESTRUCTURING COSTS During 2019, we committed to a restructuring plan to optimize our manufacturing footprint and to improve our operating efficiencies and synergies related to our recent acquisitions. For the three and nine months ended September 30, 2020, we incurred severance costs primarily related to the transition and exit of our facility in Shenzhen, People’s Republic of China, and actions associated with synergies related to the Artesyn acquisition. The table below summarizes the restructuring charges: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months ​ Nine Months ​ Cumulative Cost ​ ​ Ended September 30, ​ Ended September 30, ​ Through September 30, ​ ​ 2020 ​ 2020 ​ 2020 Severance and related charges $ 202 $ 5,207 $ 12,487 Facility relocation and closure charges ​ ​ 1,292 ​ 2,733 ​ 4,730 Total restructuring charges ​ $ 1,494 $ 7,940 $ 17,217 ​ The following table summarizes our restructuring liabilities at September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred ​ Cost Paid ​ Effect of ​ ​ ​ ​ ​ Balance at ​ and ​ or ​ Changes in ​ Balance at ​ ​ December 31, ​ Charged to ​ Otherwise ​ Exchange ​ September 30, ​ ​ 2019 ​ Expense ​ Settled ​ Rates ​ 2020 Total restructuring liabilities ​ $ 2,172 ​ $ 7,940 ​ $ (3,339) ​ $ 18 ​ $ 6,791 ​ As of December 31, 2019 and September 30, 2020 the accrued restructuring liabilities related primarily to severance and related charges.

WARRANTIES

WARRANTIES	9 Months Ended
	Sep. 30, 2020
WARRANTIES
WARRANTIES	NOTE 15. WARRANTIES Provisions of our sales agreements include customary product warranties, ranging from 12 months to 24 months following installation. The estimated cost of our warranty obligation is recorded when revenue is recognized and is based upon our historical experience by product and configuration. Our estimated warranty obligation is included in Other accrued expenses in our Unaudited Consolidated Balance Sheets. Changes in our product warranty obligation are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Balances at beginning of period ​ $ 6,072 ​ $ 3,263 ​ $ 6,413 ​ $ 2,084 ​ Warranty acquired in business combinations ​ — ​ 3,618 ​ — ​ 4,818 ​ Increases to accruals ​ 1,097 ​ 286 ​ 2,608 ​ 890 ​ Warranty expenditures ​ (1,458) ​ (414) ​ (3,325) ​ (1,045) ​ Effect of changes in exchange rates ​ 10 ​ (11) ​ 25 ​ (5) ​ Balances at end of period ​ $ 5,721 ​ $ 6,742 ​ $ 5,721 ​ $ 6,742 ​ ​

LEASES

LEASES	9 Months Ended
	Sep. 30, 2020
LEASES
LEASES	NOTE 16. LEASES We lease manufacturing and office space under non-cancelable operating leases. Some of these leases contain provisions for landlord funded leasehold improvements which are recorded as a reduction to right-of-use (“ROU”) assets and the related operating lease liabilities. For leases containing an option to renew, we regularly evaluate the renewal options and when they are reasonably certain of exercise, we include the renewal period in our lease terms, along with the ROU assets and operating lease liabilities. In many cases, we have lease terms that are less than one year and therefore, we have elected the practical expedient to exclude these short-term leases from our ROU assets and operating lease liabilities. New leases are negotiated and executed to meet business objectives on an on-going basis. Our leases do not provide an implicit rate. Accordingly, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. We have a centrally managed treasury function; therefore, we apply a portfolio approach for determining the incremental borrowing rate applicable to the lease term. Components of operating lease cost were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Operating lease cost ​ $ 4,806 ​ $ 2,733 ​ $ 14,500 ​ $ 6,583 Short-term and variable lease cost ​ ​ 1,504 ​ ​ 1,165 ​ ​ 4,151 ​ ​ 2,854 Total operating lease cost ​ $ 6,310 ​ $ 3,898 ​ $ 18,651 ​ $ 9,437 ​ Maturities of our operating lease liabilities at September 30, 2020 are as follows: ​ ​ ​ ​ ​ Year Ending December 31, ​ 2020 (remaining) ​ $ 5,669 2021 ​ 20,609 2022 ​ 15,818 2023 ​ 12,689 2024 ​ ​ 11,356 Thereafter ​ ​ 83,531 Total lease payments ​ ​ 149,672 Less: Interest ​ ​ (34,825) Present value of lease liabilities ​ $ 114,847 ​ Other information related to leases, including supplemental cash flow information, consists of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Cash paid for operating leases ​ ​ $ 5,934 ​ $ 2,936 ​ $ 17,336 ​ $ 8,850 Right-of-use assets obtained in exchange for operating lease liabilities (1) ​ ​ $ 9,586 ​ $ 56,319 ​ $ 34,064 ​ $ 113,874 (1) In the three months ended March 31, 2019, we implemented ASC 842, Leases . The previously reported amount includes leases existing on January 1, 2019. In the three months ended September 30, 2019, we obtained $56.3 million in right-of-use assets in connection with the Artesyn acquisition. ​ The weighted average remaining lease term and discount rate related to our lease liabilities as of September 30, 2020 were 10.8 years and 4.5%, respectively. As of September 30, 2019, the weighted average remaining lease term and discount rate related to our lease liabilities were 8.7 years and 4.0%, respectively.

PENSION LIABILITY

PENSION LIABILITY	9 Months Ended
	Sep. 30, 2020
PENSION LIABILITY
PENSION LIABILITY	NOTE 17. PENSION LIABILITY In connection with the acquisitions of HiTek Power Group, LumaSense and Artesyn’s Embedded Power business, we assumed the liabilities of their pension plans. To measure the expense and related benefit obligation, various assumptions are made including discount rates used to value the obligation, expected return on plan assets used to fund these expenses and estimated future inflation rates. These assumptions are based on historical experience as well as facts and circumstances. An actuarial analysis is used to measure the expense and liability associated with pension benefits. We are committed to make annual fixed payments of $0.8 million into the HiTek Power Limited Pension Scheme through April 30, 2024, and then $1.7 million from May 1, 2024 through November 30, 2033. We are obligated to fund the other pension liabilities each year as incurred. ​ The net pension liability in our Consolidated Balance Sheets is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2020 ​ 2019 Pension liability ​ $ 70,156 ​ $ 68,359 ​ The following table sets forth the components of net periodic pension cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Service cost ​ $ 269 ​ $ 124 ​ $ 791 ​ $ 124 ​ Interest cost ​ ​ 470 ​ ​ 274 ​ ​ 1,449 ​ ​ 668 ​ Expected return on plan assets ​ (151) ​ ​ (160) ​ ​ (441) ​ ​ (496) ​ Amortization of actuarial gains and losses ​ 116 ​ ​ 90 ​ ​ 344 ​ ​ 323 ​ Net periodic pension cost ​ $ 704 ​ $ 328 ​ $ 2,143 ​ $ 619 ​ ​

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2020
STOCK-BASED COMPENSATION
STOCK-BASED COMPENSATION	NOTE 18. STOCK-BASED COMPENSATION On May 4, 2017, the stockholders approved the Company’s 2017 Omnibus Incentive Plan ("the 2017 Plan") and all shares that were then available for issuance under the 2008 Omnibus Incentive Plan are now available for issuance under the 2017 Plan. The 2017 Plan provides for the grant of stock options, stock appreciation rights, restricted stock, stock units (including deferred stock units), unrestricted stock, and dividend equivalent rights. Any of the awards issued under the 2017 Plan may be issued as performance-based awards to align compensation awards to the attainment of annual or long-term performance goals. As of September 30, 2020, there were 2.8 million shares reserved and 2.0 million shares available for grant under the 2017 Plan. ​ Restricted stock units ("RSU’s") are generally granted with a grant date fair value equal to the market price of our stock at the date of grant and with generally a three or four-year vesting schedule or performance-based vesting as determined at the time of grant. Stock option awards are generally granted with an exercise price equal to the market price of our stock at the date of grant and with either a three or four-year vesting schedule or performance-based vesting as determined at the time of grant. Stock option awards generally have a term of 10 years . We recognize stock-based compensation expense based on the fair value of the awards issued and the functional area of the employee receiving the award. Stock-based compensation was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Stock-based compensation expense ​ $ 3,781 ​ $ 917 ​ $ 9,666 ​ $ 5,053 ​ ​ Changes in the outstanding RSU awards were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date ​ ​ ​ Number of RSUs ​ Fair Value ​ RSUs outstanding at beginning of period 534 ​ $ 56.56 RSUs granted 336 ​ $ 59.33 RSUs vested (150) ​ $ 57.16 RSUs forfeited (38) ​ $ 59.38 RSUs outstanding at end of period 682 ​ $ 57.97 ​ Changes in our outstanding stock options were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ ​ Average ​ ​ ​ Number of ​ Exercise Price ​ ​ ​ Options ​ per Share ​ Options outstanding at beginning of period 185 ​ $ 21.56 Options exercised (32) ​ $ 13.39 Options forfeited — ​ $ — Options expired (4) ​ $ 15.58 Options outstanding at end of period 149 ​ $ 23.48 ​

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2020
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	NOTE 19. COMMITMENTS AND CONTINGENCIES We have firm purchase commitments and agreements with various suppliers to ensure the availability of components. Purchase commitments as of September 30, 2020 are approximately $178.1 million. Our policy with respect to all purchase commitments is to record losses, if any, when they are probable and reasonably estimable. We continuously monitor these commitments for exposure to potential losses and will record a provision for losses when it is deemed necessary. We are involved in disputes and legal actions arising in the normal course of our business. There have been no material developments in legal proceedings in which we are involved during the three and nine months ended September 30, 2020.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2020
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	NOTE 20. RELATED PARTY TRANSACTIONS Members of our Board of Directors hold various executive positions and serve as directors at other companies, including companies that are our customers. We engaged in the following transactions with companies related to members of our Board of Directors, as described below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Sales to related parties ​ $ 2 ​ $ 287 ​ $ 2 ​ $ 1,299 ​ Number of related party customers ​ 1 ​ 1 ​ 1 ​ 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Accounts receivable from related parties ​ $ 2 ​ $ — Number of related party customers ​ 1 ​ 1 ​ We did not have any outstanding accounts payable with our related parties as of September 30, 2020 or December 31, 2019.

SIGNIFICANT CUSTOMER INFORMATIO

SIGNIFICANT CUSTOMER INFORMATION	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT CUSTOMER INFORMATION
SIGNIFICANT CUSTOMER INFORMATION	NOTE 21. SIGNIFICANT CUSTOMER INFORMATION The following table summarizes sales, and percentages of sales, by customers that individually accounted for 10% or more of our sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 65,740 16.9 % $ 38,957 22.2 % LAM Research ​ $ 40,798 10.5 % ​ $ 21,991 12.6 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 181,129 17.3 % $ 108,978 24.2 % LAM Research ​ * * % ​ $ 61,364 13.6 % ​ * Customer’s balance was less than 10% of the total sales balance. ​ The following table summarizes the accounts receivable balances, and percentages of the total accounts receivable, for customers that individually accounted for 10% or more of accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30 ​ December 31, ​ ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 39,015 16.2 % $ 36,849 14.9 % Nidec Motor Corporation ​ ​ * ​ * % ​ 38,071 ​ 15.4 % ​ * Customer’s balance was less than 10% of the total accounts receivable balance. ​ Our sales to Applied Materials, Inc. and LAM Research include precision power products used in semiconductor processing and solar and flat panel display. Our sales to Nidec Motor Corporation are primarily embedded power products used in industrial motor drives. No other customer accounted for 10% or more of our sales or accounts receivable balances during these periods.

CREDIT FACILITY

CREDIT FACILITY	9 Months Ended
	Sep. 30, 2020
CREDIT FACILITY
CREDIT FACILITY	NOTE 22. CREDIT FACILITY In September 2019, in connection with the Artesyn Acquisition Agreement, the Company entered into a credit agreement (“Credit Agreement”) that provided aggregate financing of $500.0 million, consisting of a $350.0 million senior unsecured term loan facility (the “Term Loan Facility”) and a $150.0 million senior unsecured revolving facility the (“Revolving Facility”). Both the Term Loan Facility and Revolving Facility mature on September 10, 2024. The Revolving Facility and Term Loan Facility bear interest, at the option of the Company, at a rate based on a reserve adjusted “Eurodollar Rate” or “Base Rate” plus an applicable margin. Additionally, the Revolving Facility is subject to an unused line fee. As of September 30, 2020, the unused line fee was 0.10%. As of September 30, 2020, the Company had $150.0 million available to withdraw on the Revolving Facility and was in compliance with all covenants. The fair value of the Company’s outstanding ​ The debt obligation on our Unaudited Consolidated Balance Sheets consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Debt: ​ ​ ​ ​ ​ ​ Term Loan Facility ​ $ 328,125 ​ $ 341,250 Less: debt issuance costs ​ ​ (1,831) ​ ​ (2,223) Total debt ​ ​ 326,294 ​ ​ 339,027 Less current portion of long-term debt ​ ​ (17,500) ​ ​ (17,500) Total long-term debt ​ $ 308,794 ​ $ 321,527 ​ Contractual maturities of the Company’s debt obligations, excluding amortization of debt issuance costs are as follows: ​ ​ ​ ​ ​ Year Ending December 31, Amount 2020 (remaining) ​ $ 4,375 2021 ​ ​ 17,500 2022 ​ ​ 17,500 2023 ​ ​ 17,500 2024 ​ ​ 271,250 Total ​ $ 328,125 ​ Interest expense and unused line of credit fees were recorded in the Other income (expense), net, in our Unaudited Consolidated Statements of Operations as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Interest expense ​ $ 778 ​ $ 703 ​ $ 4,021 ​ $ 703 ​ Amortization of debt issuance costs ​ ​ 129 ​ ​ 45 ​ ​ 392 ​ ​ 45 ​ Unused line of credit fees and other ​ ​ 38 ​ ​ 60 ​ ​ 114 ​ ​ 179 ​ Total interest expense ​ $ 945 ​ $ 808 ​ $ 4,527 ​ $ 927 ​ ​

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	9 Months Ended
	Sep. 30, 2020
BASIS OF PRESENTATION
Use of Estimates in the Preparation of the Consolidated Financial Statements	Use of Estimates in the Preparation of the Consolidated Financial Statements The preparation of our Consolidated Financial Statements in conformity with U.S. GAAP requires us to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, and disclosure of contingent liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. We believe the significant estimates, assumptions, and judgments when accounting for items and matters such as allowances for expected credit loss, excess and obsolete inventory, warranty reserves, right-of-use assets and related operating lease liabilities, acquisitions, asset valuations, asset life, depreciation, amortization, recoverability of assets, impairments, deferred revenue, stock option and restricted stock grants, taxes, and other provisions are reasonable, based upon information available at the time they are made. Actual results may differ from these estimates, making it possible that a change in these estimates could occur in the near term.
Derivatives	Derivatives The Company uses derivative financial instruments to manage risks associated with foreign currency and interest rate fluctuations. Unless we meet specific hedge accounting criteria, changes in the fair value of derivative financial instruments are recognized in the Consolidated Statements of Operations within Other income (expense), net. For derivatives designated as cash flow hedges, changes in fair value are recorded to Accumulated other comprehensive income (loss) on the Consolidated Balance Sheets and are reclassified to earnings when the underlying forecasted transaction affects earnings. We reassess the probability of the underlying forecasted transactions occurring on a quarterly basis.
Fair Value	Fair Value We value our financial assets and liabilities using fair value measurements. U.S. GAAP for fair value establishes a hierarchy that prioritizes fair value measurements based on the types of inputs used for the various valuation techniques (market approach, income approach, and cost approach). The Company’s financial assets and liabilities are measured using inputs from the three levels of the fair value hierarchy. The three levels of the hierarchy and the related inputs are as follows: ● Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities that the entity can access at the measurement date. ● Level 2 — Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ● Level 3 — Unobservable inputs for the asset or liability. The Company categorizes fair value measurements within the fair value hierarchy based upon the lowest level of the most significant inputs used to determine fair value. Our assessment of the significance of a particular input to the fair value measurement requires judgement and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels. The carrying amounts of our cash and cash equivalents, accounts receivable, accounts payable and other current assets and liabilities approximate fair value as recorded due to the short-term nature of these instruments. The Company’s non-financial assets, which primarily consist of property and equipment, goodwill, and other intangible assets, are not required to be carried at fair value on a recurring basis and are reported at carrying value. However, on a periodic basis or whenever events or changes in circumstances indicate that their carrying value may not be fully recoverable (and at least annually for goodwill and indefinite-lived intangible assets), non-financial instruments are assessed for impairment and, if applicable, written down to and recorded at fair value. See Note 12, Goodwill, Note 13, Intangible Assets, The fair value of borrowings approximates the recorded borrowing value based upon market interest rates for similar facilities. See Note 22, Credit Facility
New Accounting Standards	New Accounting Standards From time to time, the Financial Accounting Standards Board ("FASB") or other standards setting bodies issue new accounting pronouncements. Updates to the FASB Accounting Standards Codification ("ASC") are communicated through issuance of an Accounting Standards Update ("ASU"). Unless otherwise discussed, we believe that the impact of recently issued guidance, whether adopted or to be adopted in the future, is not expected to have a material impact on the Consolidated Financial Statements upon adoption. Recently issued accounting pronouncements not yet adopted In August 2018, the FASB issued ASU 2018-14, "Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20)" ("ASU 2018-14"). ASU 2018-14 eliminates requirements for certain disclosures and requires additional disclosures under defined benefit pension plans and other post-retirement plans. ASU 2018-14 is effective for fiscal years ending after December 15, 2020 and shall be applied to all periods presented on a retrospective basis. Early adoption is permitted. We are currently assessing and do not believe ASU 2018-14 will have a significant impact on our defined benefit plan disclosure requirements. In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (“ASU 2020-04”). ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another rate that is expected to be discontinued. ASU 2020-04 will be in effect through December 31, 2022. We are currently assessing the potential impact of ASU 2020-04 on our Consolidated Financial Statements. Recently adopted accounting pronouncements In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses (Topic 326)" The Company’s principal customers are original equipment manufacturers and end user customers, which operate globally through wholly owned subsidiaries that purchase the Company’s products under substantially the same credit terms, with similar historical credit risks. As a result, the Company assesses credit risks for its customers as a single group. The Company evaluates collection risk and establishes its expected credit loss primarily through a combination of the following: an assessment of customer credit risk ratings utilizing third party credit risk data, analysis of historical aging and credit loss experience, and customer specific information. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820)" In December 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes"

BUSINESS ACQUISITIONS (Tables)

BUSINESS ACQUISITIONS (Tables)	9 Months Ended
	Sep. 30, 2020
Business Acquisition [Line Items]
Summary of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization ​ ​ ​ ​ ​ ​ ​ Method ​ Useful Life ​ Technology ​ $ 28,000 Straight-line 5 ​ Customer relationships ​ 75,000 Straight-line 15 ​ Tradename ​ 21,000 Straight-line 10 ​ Total ​ $ 124,000 ​
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Schedule of components of fair value of total consideration transferred	​ ​ ​ ​ ​ ​ ​ ​ Cash paid for acquisition ​ $ 390,453 Contingent consideration ​ ​ 3,008 Total fair value of consideration transferred ​ ​ 393,461 Less cash acquired ​ (23,225) Total purchase price ​ $ 370,236
Schedule of fair value of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Preliminary Measurement Final Fair Accounts and other receivable, net ​ $ 132,466 ​ $ — ​ $ 132,466 Inventories ​ 156,407 ​ ​ — ​ ​ 156,407 Property and equipment ​ 63,321 ​ ​ — ​ ​ 63,321 Operating lease right-of-use assets ​ ​ 54,439 ​ ​ — ​ ​ 54,439 Goodwill ​ 117,762 ​ ​ (2,764) ​ ​ 114,998 Intangible assets ​ 124,000 ​ ​ — ​ ​ 124,000 Other assets ​ 63,863 ​ ​ (649) ​ ​ 63,214 Total assets acquired ​ 712,258 ​ ​ (3,413) ​ ​ 708,845 Accounts payable ​ 152,635 ​ ​ — ​ ​ 152,635 Operating lease liability ​ ​ 54,515 ​ ​ — ​ ​ 54,515 Pension liability ​ ​ 48,315 ​ ​ — ​ ​ 48,315 Deferred income tax liabilities ​ 5,870 ​ ​ (4,175) ​ ​ 1,695 Other liabilities ​ 86,648 ​ ​ (5,199) ​ ​ 81,449 Total liabilities assumed ​ 347,983 ​ ​ (9,374) ​ ​ 338,609 Total fair value of net assets acquired ​ $ 364,275 ​ $ 5,961 ​ $ 370,236
Schedule of unaudited pro forma information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2019 ​ 2019 ​ As Reported Pro Forma As Reported Pro Forma Total sales $ 175,127 $ 293,658 $ 450,680 $ 864,522 Net income attributable to Advanced Energy Industries, Inc. $ 7,621 $ 12,577 $ 54,677 $ 54,622 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ Basic earnings per share ​ $ 0.20 ​ $ 0.33 ​ $ 1.43 ​ $ 1.43 Diluted earnings per share ​ $ 0.20 ​ $ 0.33 ​ $ 1.42 ​ $ 1.42

REVENUE (Tables)

REVENUE (Tables)	9 Months Ended
	Sep. 30, 2020
REVENUE
Schedule of disaggregation of revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Semiconductor Equipment ​ $ 167,058 ​ $ 96,426 ​ $ 446,107 ​ $ 277,911 ​ Industrial & Medical ​ 87,013 ​ 55,187 ​ 219,877 ​ 149,255 ​ Data Center Computing ​ ​ 87,741 ​ ​ 13,498 ​ ​ 257,240 ​ ​ 13,498 ​ Telecom & Networking ​ ​ 47,709 ​ ​ 10,016 ​ ​ 121,633 ​ ​ 10,016 ​ Total ​ $ 389,521 ​ $ 175,127 ​ $ 1,044,857 ​ $ 450,680 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 ​ 2019 2020 ​ 2019 North America ​ $ 190,629 $ 83,632 ​ $ 504,719 $ 203,531 Asia ​ 180,660 ​ 66,157 ​ ​ 462,388 ​ 175,554 Europe ​ 17,886 ​ 25,008 ​ ​ 76,070 ​ 70,526 Other ​ 346 ​ 330 ​ ​ 1,680 ​ 1,069 Total ​ $ 389,521 $ 175,127 ​ $ 1,044,857 $ 450,680 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Product and service revenue recognized at point in time ​ $ 389,306 ​ $ 174,827 ​ $ 1,044,255 ​ $ 448,964 ​ Extended warranty and service contracts recognized over time ​ 215 ​ 300 ​ 602 ​ 1,716 ​ Total ​ $ 389,521 ​ $ 175,127 ​ $ 1,044,857 ​ $ 450,680 ​

DISPOSED AND DISCONTINUED OPE_2

DISPOSED AND DISCONTINUED OPERATIONS (Tables)	9 Months Ended
	Sep. 30, 2020
DISPOSED AND DISCONTINUED OPERATIONS
Schedule of disposal groups, including discontinued operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Sales ​ $ — ​ $ — ​ $ — ​ $ — ​ Cost of sales ​ — ​ (700) ​ — ​ (900) ​ Total operating expense ​ 128 ​ 133 ​ 533 ​ 514 ​ Operating income (loss) from discontinued operations ​ (128) ​ 567 ​ (533) ​ 386 ​ Other income (expense) ​ 151 ​ (84) ​ (1) ​ 10,835 ​ Income (loss) from discontinued operations before income taxes ​ 23 ​ 483 ​ (534) ​ 11,221 ​ Provision (benefit) for income taxes ​ (27) ​ 108 ​ (113) ​ 2,531 ​ Income (loss) from discontinued operations, net of income taxes ​ $ 50 ​ $ 375 ​ $ (421) ​ $ 8,690 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Cash and cash equivalents $ — $ — Accounts and other receivables, net ​ ​ — ​ ​ — Inventories ​ ​ 23 ​ ​ 30 Other current assets ​ ​ 23 ​ ​ 30 Other assets ​ ​ — ​ ​ — Deferred income tax assets ​ 269 ​ 269 Deposits and other assets ​ ​ 269 ​ ​ 269 Accounts payable and other accrued expenses ​ ​ 137 ​ ​ — Accrued warranty ​ 894 ​ 914 Other accrued expenses ​ ​ 1,031 ​ ​ 914 Accrued warranty ​ ​ 310 ​ ​ 698 Other liabilities ​ 215 ​ 189 Other long-term liabilities ​ $ 525 ​ $ 887

INCOME TAXES (Tables)

INCOME TAXES (Tables)	9 Months Ended
	Sep. 30, 2020
INCOME TAXES
Schedule of tax expense and the effective tax rate for income from continuing operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Income from continuing operations, before income taxes ​ $ 52,396 ​ $ 10,751 ​ $ 108,583 ​ $ 49,835 ​ Provision for income taxes ​ $ 6,783 ​ $ 3,495 ​ $ 15,293 ​ $ 3,819 ​ Effective tax rate ​ ​ 12.9 % ​ 32.5 % ​ 14.1 % ​ 7.7 %

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2020
EARNINGS PER SHARE
Reconciliation of weighted-average shares outstanding used in calculation of basic and diluted EPS	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Income from continuing operations ​ $ 45,613 ​ $ 7,256 ​ $ 93,290 ​ $ 46,016 ​ Income from continuing operations attributable to noncontrolling interest ​ 36 ​ 10 ​ 35 ​ 29 ​ Income from continuing operations attributable to Advanced Energy Industries, Inc. ​ $ 45,577 ​ $ 7,246 ​ $ 93,255 ​ $ 45,987 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted-average common shares outstanding ​ 38,325 ​ 38,313 ​ 38,322 ​ 38,258 ​ Assumed exercise of dilutive stock options and restricted stock units ​ 203 ​ 176 ​ 209 ​ 199 ​ Diluted weighted-average common shares outstanding ​ 38,528 ​ 38,489 ​ 38,531 ​ 38,457 ​ Continuing operations: ​ ​ ​ ​ ​ Basic earnings per share ​ $ 1.19 ​ $ 0.19 ​ $ 2.43 ​ $ 1.20 ​ Diluted earnings per share ​ $ 1.18 ​ $ 0.19 ​ $ 2.42 ​ $ 1.20 ​
Schedule of stock options and restricted units excluded in computation of diluted EPS	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Restricted stock units — 4 — 1
Schedule of repurchase of shares of common stock	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ (in thousands, except per share amounts) 2020 2019 2020 2019 ​ Amount paid to repurchase shares ​ $ 4,331 ​ $ — ​ $ 11,579 ​ $ — ​ Number of shares repurchased ​ 73 ​ — ​ 243 ​ — ​ Average repurchase price per share ​ $ 59.70 ​ $ — ​ $ 47.70 ​ $ — ​

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2020
FAIR VALUE MEASUREMENTS
Schedule of assets and liabilities measured at fair value on a recurring basis	The following tables present information about the Company’s assets and liabilities measured at fair value on a recurring basis. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 Description ​ Balance Sheet Classification ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ — ​ $ 2,601 ​ $ — ​ $ 2,601 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,601 ​ $ — ​ $ 2,601 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other long-term liabilities ​ $ — ​ $ — ​ $ 3,359 ​ $ 3,359 Interest rate swaps ​ Other long-term liabilities ​ ​ — ​ ​ 3,466 ​ ​ — ​ ​ 3,466 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 3,466 ​ $ 3,359 ​ $ 6,825 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 Description ​ Balance Sheet Classification ​ Level 1 Level 2 Level 3 Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ ​ ​ $ 2,614 ​ $ — ​ $ 2,614 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,614 ​ $ — ​ $ 2,614 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other long-term liabilities ​ $ — ​ $ — ​ $ 1,377 ​ $ 1,377 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ — ​ $ 1,377 ​ $ 1,377

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2020
DERIVATIVE FINANCIAL INSTRUMENTS
Schedule of notional amount of qualified hedging instruments	The following table summarizes the notional amount of the Company’s qualified hedging instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Interest rate swap contracts ​ $ 277,594 ​ $ —
Schedule of activity related to qualified hedging instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Gain (loss) recognized in Other comprehensive income (loss), net of tax ​ $ 170 ​ $ — ​ $ (2,674) ​ $ —

ACCOUNTS AND OTHER RECEIVABLE (

ACCOUNTS AND OTHER RECEIVABLE (Tables)	9 Months Ended
	Sep. 30, 2020
ACCOUNTS AND OTHER RECEIVABLE
Schedule of accounts and other receivable	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Amounts billed, net ​ $ 221,447 ​ $ 227,528 Unbilled receivables ​ ​ 18,700 ​ 19,036 Total receivables, net ​ $ 240,147 ​ $ 246,564
Schedule of expected credit losses	​ ​ ​ ​ ​ December 31, 2019 $ 7,745 Additions ​ 407 Deductions - write-offs, net of recoveries ​ (482) September 30, 2020 ​ $ 7,670

INVENTORIES (Tables)

INVENTORIES (Tables)	9 Months Ended
	Sep. 30, 2020
INVENTORIES
Schedule of components of inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 ​ Parts and raw materials ​ $ 155,217 ​ $ 134,816 ​ Work in process ​ 17,147 ​ 10,269 ​ Finished goods ​ 85,010 ​ 84,934 ​ Total ​ $ 257,374 ​ $ 230,019 ​

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2020
PROPERTY AND EQUIPMENT
Schedule of details of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 ​ Buildings and land ​ $ 1,654 ​ $ 1,693 ​ Machinery and equipment ​ 107,038 ​ 108,945 ​ Computer and communication equipment ​ 25,258 ​ 29,106 ​ Furniture and fixtures ​ 4,203 ​ 4,119 ​ Vehicles ​ 261 ​ 262 ​ Leasehold improvements ​ 41,590 ​ 33,041 ​ Construction in process ​ 12,259 ​ 9,089 ​ ​ ​ 192,263 ​ 186,255 ​ Less: Accumulated depreciation ​ (82,288) ​ (78,146) ​ Property and equipment, net ​ $ 109,975 ​ $ 108,109 ​
Schedule of depreciation expense recorded in continuing operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Depreciation expense ​ $ 7,188 ​ $ 3,903 ​ $ 20,369 ​ $ 8,452 ​

GOODWILL (Tables)

GOODWILL (Tables)	9 Months Ended
	Sep. 30, 2020
GOODWILL AND INTANGIBLE ASSETS
Schedule of changes in goodwill	​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 $ 202,932 Measurement period adjustments to purchase price allocation ​ ​ 1,957 Foreign currency translation ​ ​ 1,670 September 30, 2020 ​ $ 206,559

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	9 Months Ended
	Sep. 30, 2020
GOODWILL AND INTANGIBLE ASSETS
Schedule of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying September 30, 2020 ​ Amount ​ Amortization ​ Amount Technology ​ $ 83,882 ​ $ (22,012) ​ $ 61,870 Customer relationships ​ 109,514 ​ (24,302) ​ 85,212 Trademarks and other ​ 26,892 ​ (4,724) ​ 22,168 Total ​ $ 220,288 ​ $ (51,038) ​ $ 169,250 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying December 31, 2019 ​ Amount ​ Amortization ​ Amount Technology ​ $ 83,368 ​ $ (14,250) ​ $ 69,118 Customer relationships ​ 108,995 ​ (18,197) ​ 90,798 Trademarks and other ​ 26,888 ​ (2,793) ​ 24,095 Total ​ $ 219,251 ​ $ (35,240) ​ $ 184,011
Schedule of amortization expense related to intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Amortization expense ​ $ 5,049 ​ $ 3,002 ​ $ 15,064 ​ $ 6,849 ​
Schedule of estimated amortization expense related to intangible assets	​ ​ ​ ​ ​ Year Ending December 31, ​ ​ 2020 (remaining) ​ $ 5,049 2021 ​ 20,093 2022 ​ 19,815 2023 ​ 19,796 2024 ​ 16,926 Thereafter ​ 87,571 Total ​ $ 169,250

RESTRUCTURING COSTS (Tables)

RESTRUCTURING COSTS (Tables)	9 Months Ended
	Sep. 30, 2020
RESTRUCTURING COSTS
Schedule of restructuring charges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months ​ Nine Months ​ Cumulative Cost ​ ​ Ended September 30, ​ Ended September 30, ​ Through September 30, ​ ​ 2020 ​ 2020 ​ 2020 Severance and related charges $ 202 $ 5,207 $ 12,487 Facility relocation and closure charges ​ ​ 1,292 ​ 2,733 ​ 4,730 Total restructuring charges ​ $ 1,494 $ 7,940 $ 17,217
Schedule of restructuring liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred ​ Cost Paid ​ Effect of ​ ​ ​ ​ ​ Balance at ​ and ​ or ​ Changes in ​ Balance at ​ ​ December 31, ​ Charged to ​ Otherwise ​ Exchange ​ September 30, ​ ​ 2019 ​ Expense ​ Settled ​ Rates ​ 2020 Total restructuring liabilities ​ $ 2,172 ​ $ 7,940 ​ $ (3,339) ​ $ 18 ​ $ 6,791

WARRANTIES (Tables)

WARRANTIES (Tables)	9 Months Ended
	Sep. 30, 2020
WARRANTIES
Schedule of changes in accrued product warranties	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Balances at beginning of period ​ $ 6,072 ​ $ 3,263 ​ $ 6,413 ​ $ 2,084 ​ Warranty acquired in business combinations ​ — ​ 3,618 ​ — ​ 4,818 ​ Increases to accruals ​ 1,097 ​ 286 ​ 2,608 ​ 890 ​ Warranty expenditures ​ (1,458) ​ (414) ​ (3,325) ​ (1,045) ​ Effect of changes in exchange rates ​ 10 ​ (11) ​ 25 ​ (5) ​ Balances at end of period ​ $ 5,721 ​ $ 6,742 ​ $ 5,721 ​ $ 6,742 ​

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2020
LEASES
Components of operating lease cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Operating lease cost ​ $ 4,806 ​ $ 2,733 ​ $ 14,500 ​ $ 6,583 Short-term and variable lease cost ​ ​ 1,504 ​ ​ 1,165 ​ ​ 4,151 ​ ​ 2,854 Total operating lease cost ​ $ 6,310 ​ $ 3,898 ​ $ 18,651 ​ $ 9,437
Schedule of maturities of operating lease liabilities	​ ​ ​ ​ ​ Year Ending December 31, ​ 2020 (remaining) ​ $ 5,669 2021 ​ 20,609 2022 ​ 15,818 2023 ​ 12,689 2024 ​ ​ 11,356 Thereafter ​ ​ 83,531 Total lease payments ​ ​ 149,672 Less: Interest ​ ​ (34,825) Present value of lease liabilities ​ $ 114,847
Schedule of other information related to leases	Other information related to leases, including supplemental cash flow information, consists of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2020 2019 2020 2019 Cash paid for operating leases ​ ​ $ 5,934 ​ $ 2,936 ​ $ 17,336 ​ $ 8,850 Right-of-use assets obtained in exchange for operating lease liabilities (1) ​ ​ $ 9,586 ​ $ 56,319 ​ $ 34,064 ​ $ 113,874 (1) In the three months ended March 31, 2019, we implemented ASC 842, Leases . The previously reported amount includes leases existing on January 1, 2019. In the three months ended September 30, 2019, we obtained $56.3 million in right-of-use assets in connection with the Artesyn acquisition.

PENSION LIABILITY (Tables)

PENSION LIABILITY (Tables)	9 Months Ended
	Sep. 30, 2020
PENSION LIABILITY
Schedule of net pension liability	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2020 ​ 2019 Pension liability ​ $ 70,156 ​ $ 68,359
Schedule of net periodic pension benefit costs	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Service cost ​ $ 269 ​ $ 124 ​ $ 791 ​ $ 124 ​ Interest cost ​ ​ 470 ​ ​ 274 ​ ​ 1,449 ​ ​ 668 ​ Expected return on plan assets ​ (151) ​ ​ (160) ​ ​ (441) ​ ​ (496) ​ Amortization of actuarial gains and losses ​ 116 ​ ​ 90 ​ ​ 344 ​ ​ 323 ​ Net periodic pension cost ​ $ 704 ​ $ 328 ​ $ 2,143 ​ $ 619 ​

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of stock-based compensation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Stock-based compensation expense ​ $ 3,781 ​ $ 917 ​ $ 9,666 ​ $ 5,053 ​
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date ​ ​ ​ Number of RSUs ​ Fair Value ​ RSUs outstanding at beginning of period 534 ​ $ 56.56 RSUs granted 336 ​ $ 59.33 RSUs vested (150) ​ $ 57.16 RSUs forfeited (38) ​ $ 59.38 RSUs outstanding at end of period 682 ​ $ 57.97
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ ​ Average ​ ​ ​ Number of ​ Exercise Price ​ ​ ​ Options ​ per Share ​ Options outstanding at beginning of period 185 ​ $ 21.56 Options exercised (32) ​ $ 13.39 Options forfeited — ​ $ — Options expired (4) ​ $ 15.58 Options outstanding at end of period 149 ​ $ 23.48

RELATED PARTY TRANSACTIONS (Tab

RELATED PARTY TRANSACTIONS (Tables)	9 Months Ended
	Sep. 30, 2020
RELATED PARTY TRANSACTIONS
Schedule of related party transactions	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Sales to related parties ​ $ 2 ​ $ 287 ​ $ 2 ​ $ 1,299 ​ Number of related party customers ​ 1 ​ 1 ​ 1 ​ 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Accounts receivable from related parties ​ $ 2 ​ $ — Number of related party customers ​ 1 ​ 1

SIGNIFICANT CUSTOMER INFORMAT_2

SIGNIFICANT CUSTOMER INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT CUSTOMER INFORMATION
Schedule of revenue by major customers by reporting segments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 65,740 16.9 % $ 38,957 22.2 % LAM Research ​ $ 40,798 10.5 % ​ $ 21,991 12.6 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 181,129 17.3 % $ 108,978 24.2 % LAM Research ​ * * % ​ $ 61,364 13.6 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30 ​ December 31, ​ ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 39,015 16.2 % $ 36,849 14.9 % Nidec Motor Corporation ​ ​ * ​ * % ​ 38,071 ​ 15.4 %

CREDIT FACILITY (Tables)

CREDIT FACILITY (Tables)	9 Months Ended
	Sep. 30, 2020
CREDIT FACILITY
Schedule of debt obligation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2020 2019 Debt: ​ ​ ​ ​ ​ ​ Term Loan Facility ​ $ 328,125 ​ $ 341,250 Less: debt issuance costs ​ ​ (1,831) ​ ​ (2,223) Total debt ​ ​ 326,294 ​ ​ 339,027 Less current portion of long-term debt ​ ​ (17,500) ​ ​ (17,500) Total long-term debt ​ $ 308,794 ​ $ 321,527
Schedule of contractual maturities of debt obligations	​ ​ ​ ​ ​ Year Ending December 31, Amount 2020 (remaining) ​ $ 4,375 2021 ​ ​ 17,500 2022 ​ ​ 17,500 2023 ​ ​ 17,500 2024 ​ ​ 271,250 Total ​ $ 328,125
Schedule of interest expense and unused line of credit fees	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2020 2019 2020 2019 ​ Interest expense ​ $ 778 ​ $ 703 ​ $ 4,021 ​ $ 703 ​ Amortization of debt issuance costs ​ ​ 129 ​ ​ 45 ​ ​ 392 ​ ​ 45 ​ Unused line of credit fees and other ​ ​ 38 ​ ​ 60 ​ ​ 114 ​ ​ 179 ​ Total interest expense ​ $ 945 ​ $ 808 ​ $ 4,527 ​ $ 927 ​

BUSINESS ACQUISITIONS - Acquisi

BUSINESS ACQUISITIONS - Acquisitions (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 10, 2019
Revolving Facility [Member]
Business Acquisition [Line Items]
Line of credit facility, borrowing capacity	$ 500,000
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Purchase price	$ 370,236	$ 370,236

BUSINESS ACQUISITIONS - Conside

BUSINESS ACQUISITIONS - Consideration Transferred (Details) - Artesyn's Embedded Power Business [Member] - USD ($) $ in Thousands	1 Months Ended
	Sep. 30, 2019	Sep. 10, 2019
Business Acquisition [Line Items]
Cash paid for acquisition	$ 390,453
Contingent consideration	3,008
Total fair value of consideration transferred	393,461
Less cash acquired	(23,225)
Total purchase price	$ 370,236	$ 370,236

BUSINESS ACQUISITIONS - Assets

BUSINESS ACQUISITIONS - Assets Acquired and Liabilities Assumed (Details) - Artesyn's Embedded Power Business [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 10, 2019
Business Acquisition [Line Items]
Accounts and other receivable, net		$ 132,466
Inventories		156,407
Property and equipment		63,321
Operating lease right-of-use assets		54,439
Goodwill		114,998
Intangible assets		124,000
Other assets		63,214
Total assets acquired		708,845
Accounts payable		152,635
Operating lease liability		54,515
Pension liability		48,315
Deferred income tax liabilities		1,695
Other liabilities		81,449
Total liabilities assumed		338,609
Total fair value of net assets acquired	$ 370,236	370,236
Preliminary Fair Value [Member]
Business Acquisition [Line Items]
Accounts and other receivable, net		132,466
Inventories		156,407
Property and equipment		63,321
Operating lease right-of-use assets		54,439
Goodwill		117,762
Intangible assets		124,000
Other assets		63,863
Total assets acquired		712,258
Accounts payable		152,635
Operating lease liability		54,515
Pension liability		48,315
Deferred income tax liabilities		5,870
Other liabilities		86,648
Total liabilities assumed		347,983
Total fair value of net assets acquired		364,275
Measurement Period Adjustments [Member]
Business Acquisition [Line Items]
Goodwill		(2,764)
Other assets		(649)
Total assets acquired		(3,413)
Deferred income tax liabilities		(4,175)
Other liabilities		(5,199)
Total liabilities assumed		(9,374)
Total fair value of net assets acquired		$ 5,961

BUSINESS ACQUISITIONS - Intangi

BUSINESS ACQUISITIONS - Intangible Assets Acquired (Details) - Artesyn's Embedded Power Business [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 10, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets:		$ 124,000
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets:		28,000
Useful Life	5 years
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets:		75,000
Useful Life	15 years
Tradename
Acquired Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets:		$ 21,000
Useful Life	10 years

BUSINESS ACQUISITIONS - Unaudit

BUSINESS ACQUISITIONS - Unaudited Pro Forma Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition, Pro Forma Information [Abstract]
Sales, net	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
Net income attributable to Advanced Energy Industries, Inc, As Reported	$ 45,627	$ 7,621	$ 92,834	$ 54,677
Earnings Per Share, Pro Forma [Abstract]
Basic earnings per share, As Reported	$ 1.19	$ 0.20	$ 2.42	$ 1.43
Diluted earnings per share	$ 1.19	$ 0.20	$ 2.41	$ 1.42
Artesyn's Embedded Power Business [Member]
Business Acquisition, Pro Forma Information [Abstract]
Sales, net	$ 188,800	$ 175,127	$ 502,500	$ 450,680
Total sales, Pro Forma		293,658		864,522
Net income attributable to Advanced Energy Industries, Inc, As Reported	$ 14,900	7,621	$ 23,500	54,677
Net income attributable to Advanced Energy Industries, Inc., Pro Forma		$ 12,577		$ 54,622
Earnings Per Share, Pro Forma [Abstract]
Basic earnings per share, As Reported		$ 0.20		$ 1.43
Basic earnings per share, Pro Forma		0.33		1.43
Diluted earnings per share		0.20		1.42
Diluted earnings per share, Pro Forma		$ 0.33		$ 1.42

BUSINESS ACQUISITIONS - (Detail

BUSINESS ACQUISITIONS - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Sales, net	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
Net Income	45,627	7,621	92,834	54,677
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Sales, net	188,800	175,127	502,500	450,680
Net Income	$ 14,900	$ 7,621	$ 23,500	$ 54,677

REVENUE - Nature of goods and s

REVENUE - Nature of goods and services (Details) - USD ($) $ in Millions	1 Months Ended	144 Months Ended
	May 31, 2019	Dec. 31, 2031	Sep. 30, 2020	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred revenue transferred to buyer during sale	$ 22
Deferred Service Revenue			$ 8.7	$ 9.2
Minimum | Scenario, Forecast [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Recognition of Deferred Revenue, Expected Annual Amount		$ 0.2
Maximum | Scenario, Forecast [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Recognition of Deferred Revenue, Expected Annual Amount		$ 1.1

REVENUE - Revenue by product li

REVENUE - Revenue by product line (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	190,629	83,632	504,719	203,531
Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	180,660	66,157	462,388	175,554
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	17,886	25,008	76,070	70,526
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	346	330	1,680	1,069
Semiconductor Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	167,058	96,426	446,107	277,911
Industrial And Medical [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	87,013	55,187	219,877	149,255
Data Center Computing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	87,741	13,498	257,240	13,498
Telecom And Networking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 47,709	$ 10,016	$ 121,633	$ 10,016

REVENUE - Extended Warranty Rev

REVENUE - Extended Warranty Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
Product and service revenue recognized at point in time
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	389,306	174,827	1,044,255	448,964
Extended warranty and service contracts recognized over time
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 215	$ 300	$ 602	$ 1,716

DISPOSED AND DISCONTINUED OPE_3

DISPOSED AND DISCONTINUED OPERATIONS - Disposed Operations (Details) - Grid Tied Central Solar Inverter Services Business[Member] - Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] - Bold Renewables Holdings, LLC [Member]	1 Months Ended
	May 31, 2019USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of services	$ 1
Loan	5,300,000
Amount available to borrow	$ 2,750,000
Loan term	10 years
Disposed operation of discount eligibility	30 days
Disposed operations recognized reduction to gain on sale	$ 2,300,000
Non-cash gain, net of tax expense, from discontinued operations	8,600,000
Continuing Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of extended warranty service obligation	22,000,000
Non cash gain from continuing operations	14,800,000
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of reduced liabilities held in discontinued operations	10,900,000
Tax expense from discontinued operations	$ 2,400,000
Interest Rate, First Seven Years [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of interest (percent)	0.00%
Interest Rate, Thereafter [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of interest (percent)	5.00%
Discounts On First Three Years [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of early payment discounts (percent)	50.00%
Discounts On Year Four And Five [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of early payment discounts (percent)	45.00%
Discounts Thereafter [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposed operations of early payment discounts (percent)	40.00%

DISPOSED AND DISCONTINUED OPE_4

DISPOSED AND DISCONTINUED OPERATIONS - Statement of Operations for Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
DISPOSED AND DISCONTINUED OPERATIONS
Cost of sales		$ (700)		$ (900)
Total operating expense	$ 128	133	$ 533	514
Operating income (loss) from discontinued operations	(128)	567	(533)	386
Other income (expense)	151			10,835
Other income (expense)		(84)	(1)
Income (loss) from discontinued operations before income taxes	23	483	(534)	11,221
Provision (benefit) for income taxes	(27)	108	(113)	2,531
Income (loss) from discontinued operations, net of income taxes	$ 50	$ 375	$ (421)	$ 8,690

DISPOSED AND DISCONTINUED OPE_5

DISPOSED AND DISCONTINUED OPERATIONS - Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
DISPOSED AND DISCONTINUED OPERATIONS
Inventories	$ 23	$ 30
Other current assets	23	30
Deferred income tax assets	269	269
Deposits and other assets	269	269
Accounts payable and other accrued expenses	137
Accrued warranty	894	914
Other accrued expenses	1,031	914
Accrued warranty	310	698
Other liabilities	215	189
Other long-term liabilities	$ 525	$ 887

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
INCOME TAXES
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%

INCOME TAXES - Schedule of tax

INCOME TAXES - Schedule of tax expense and effective tax rate for income from continuing operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
INCOME TAXES
Income from continuing operations, before income taxes	$ 52,396	$ 10,751	$ 108,583	$ 49,835
Provision for income taxes	$ 6,783	$ 3,495	$ 15,293	$ 3,819
Effective tax rate	12.90%	32.50%	14.10%	7.70%

EARNINGS PER SHARE - Reconcilia

EARNINGS PER SHARE - Reconciliation of weighted-average shares outstanding used in calculation of basic and diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
EARNINGS PER SHARE
Income from continuing operations	$ 45,613	$ 7,256	$ 93,290	$ 46,016
Income from continuing operations attributable to noncontrolling interest	36	10	35	29
Income from continuing operations attributable to Advanced Energy Industries, Inc.	$ 45,577	$ 7,246	$ 93,255	$ 45,987
Basic weighted-average common shares outstanding	38,325	38,313	38,322	38,258
Assumed exercise of dilutive stock options and restricted stock units	203	176	209	199
Diluted weighted-average common shares outstanding	38,528	38,489	38,531	38,457
Continuing Operations:
Basic earnings per share	$ 1.19	$ 0.19	$ 2.43	$ 1.20
Diluted earnings per share	$ 1.18	$ 0.19	$ 2.42	$ 1.20

EARNINGS PER SHARE - Schedule o

EARNINGS PER SHARE - Schedule of stock options and restricted units excluded in the computation of diluted earnings per share (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted units excluded from the computation of diluted earnings per share because they were anti-dilutive	4	1

EARNINGS PER SHARE - Stock Buyb

EARNINGS PER SHARE - Stock Buyback (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Dec. 18, 2019	May 31, 2018
EARNINGS PER SHARE
Authorized amount	$ 150,000
Authorized program period repurchase	30 months
Authorized amount increase					$ 25,100	$ 50,000
Remaining authorized repurchase amount		$ 38,400		$ 38,400
Amount paid to repurchase shares		$ 4,331	$ 7,248	$ 11,579
Number of shares repurchased		73		243
Average repurchase price per share		$ 59.70		$ 47.70

FAIR VALUE MEASUREMENTS - Asset

FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 2,601	$ 2,614
Total liabilities	6,825	1,377
Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	3,359	1,377
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	3,466
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,601	2,614
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,601	2,614
Total liabilities	3,466
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	3,466
Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,601	2,614
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	3,359	1,377
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	$ 3,359	$ 1,377

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
FAIR VALUE MEASUREMENTS
Transfers from level 1 to level 2, Assets	$ 0
Transfers from level 1 to level 2, Liabilities	0
Transfers from level 2 to level 1, Assets	0
Transfers from level 2 to level 1, Liabilities	0
Transfer into Level 3, Liabilities	0
Transfer from Level 3, Liabilities	0
Transfer into Level 3, Assets	0
Transfer from Level 3, Assets	$ 0

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Details) - Interest Rate Swap [Member] - Cash Flow Hedge - Designated as Hedging Instrument [Member]	9 Months Ended
	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Loan value, percentage	85.00%
Annual interest (as a percent)	1.271%
Average fixed rate	0.521%
Basis points at current leverage ratios	75

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS - Qualified Hedging Instruments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, notional amount	$ 277,594

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS - Activity Related to Qualified Hedging Instruments (Details) - Interest Rate Swap [Member] $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value on the interest rate swaps	$ 2,700	$ 2,700
Cash Flow Hedge | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in Other comprehensive income (loss), net of tax	$ 170	$ (2,674)

ACCOUNTS AND OTHER RECEIVABLE_2

ACCOUNTS AND OTHER RECEIVABLE (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	$ 240,147	$ 246,564
Amounts billed, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	221,447	227,528
Unbilled receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	$ 18,700	$ 19,036

ACCOUNTS AND OTHER RECEIVABLE -

ACCOUNTS AND OTHER RECEIVABLE - Expected Credit losses - (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
ACCOUNTS AND OTHER RECEIVABLE
Balances at beginning of period	$ 7,745
Additions	407
Deductions - write-offs, net of recoveries	(482)
Balances at end of period	$ 7,670

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
INVENTORIES
Parts and raw materials	$ 155,217	$ 134,816
Work in process	17,147	10,269
Finished goods	85,010	84,934
Total	$ 257,374	$ 230,019

PROPERTY AND EQUIPMENT - Detail

PROPERTY AND EQUIPMENT - Details of property and equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 192,263	$ 186,255
Less: Accumulated depreciation	(82,288)	(78,146)
Property and equipment, net	109,975	108,109
Buildings and Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,654	1,693
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	107,038	108,945
Computer and Communication Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	25,258	29,106
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,203	4,119
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	261	262
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	41,590	33,041
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12,259	$ 9,089

PROPERTY AND EQUIPMENT - Deprec

PROPERTY AND EQUIPMENT - Depreciation expense recorded in continuing operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
PROPERTY AND EQUIPMENT
Depreciation expense	$ 7,188	$ 3,903	$ 20,369	$ 8,452

GOODWILL - Schedule of the chan

GOODWILL - Schedule of the changes in goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
GOODWILL AND INTANGIBLE ASSETS
Beginning Balance	$ 202,932
Measurement period adjustments to preliminary purchase price allocation	1,957
Foreign currency translation	1,670
Ending Balance	$ 206,559

INTANGIBLE ASSETS - Schedule of

INTANGIBLE ASSETS - Schedule of intangible assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 220,288	$ 219,251
Finite-Lived Intangible Assets, Accumulated Amortization	(51,038)	(35,240)
Finite-lived intangible assets, net	169,250	184,011
Technology Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	83,882	83,368
Finite-Lived Intangible Assets, Accumulated Amortization	(22,012)	(14,250)
Finite-lived intangible assets, net	61,870	69,118
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	109,514	108,995
Finite-Lived Intangible Assets, Accumulated Amortization	(24,302)	(18,197)
Finite-lived intangible assets, net	85,212	90,798
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	26,892	26,888
Finite-Lived Intangible Assets, Accumulated Amortization	(4,724)	(2,793)
Finite-lived intangible assets, net	$ 22,168	$ 24,095

INTANGIBLE ASSETS - Schedule _2

INTANGIBLE ASSETS - Schedule of amortization expense relating to intangible assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
GOODWILL AND INTANGIBLE ASSETS
Amortization expense	$ 5,049	$ 3,002	$ 15,064	$ 6,849

INTANGIBLE ASSETS - Schedule _3

INTANGIBLE ASSETS - Schedule of Finite-Lived Intangible Assets, Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
GOODWILL AND INTANGIBLE ASSETS
2020 (remaining)	$ 5,049
2021	20,093
2022	19,815
2023	19,796
2024	16,926
Thereafter	87,571
Finite-lived intangible assets, net	$ 169,250	$ 184,011

RESTRUCTURING COSTS (Details)

RESTRUCTURING COSTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		33 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 1,494	$ 152	$ 7,940	$ 3,620	$ 17,217
Severance and related charges
Restructuring Cost and Reserve [Line Items]
Restructuring expense	202		5,207		12,487
Facility relocation and closure charges
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 1,292		$ 2,733		$ 4,730

RESTRUCTURING COSTS - Schedule

RESTRUCTURING COSTS - Schedule of Restructuring liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		33 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Beginning balance			$ 2,172
Cost incurred and charged to expense	$ 1,494	$ 152	7,940	$ 3,620	$ 17,217
Cost paid or otherwise settled			(3,339)
Effect of change in exchange rates			18
Ending balance	$ 6,791		$ 6,791		$ 6,791

WARRANTIES - Narrative (Details

WARRANTIES - Narrative (Details)	9 Months Ended
	Sep. 30, 2020
Minimum
Product Liability Contingency [Line Items]
Standard Product Warranty Term	12 months
Maximum
Product Liability Contingency [Line Items]
Standard Product Warranty Term	24 months

WARRANTIES - Changes in Product

WARRANTIES - Changes in Product Warranty Obligation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Movement in Standard Product Warranty Accrual [Roll Forward]
Balances at beginning of period	$ 6,072	$ 3,263	$ 6,413	$ 2,084
Warranty acquired in business combinations		3,618		4,818
Increases to accruals	1,097	286	2,608	890
Warranty expenditures	(1,458)	(414)	(3,325)	(1,045)
Effect of changes in exchange rates	10	(11)	25	(5)
Balances at end of period	$ 5,721	$ 6,742	$ 5,721	$ 6,742

LEASES - Components of operatin

LEASES - Components of operating lease cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
LEASES
Operating lease cost	$ 4,806	$ 2,733	$ 14,500	$ 6,583
Short-term and variable lease cost	1,504	1,165	4,151	2,854
Total operating lease costs	$ 6,310	$ 3,898	$ 18,651	$ 9,437

LEASES - Operating lease maturi

LEASES - Operating lease maturity schedule (Details) $ in Thousands	Sep. 30, 2020USD ($)
LEASES
2020 (remaining)	$ 5,669
2021	20,609
2022	15,818
2023	12,689
2024	11,356
Thereafter	83,531
Total lease payments	149,672
Less: Interest	(34,825)
Present value of lease liabilities	$ 114,847

LEASES - Other lease cost infor

LEASES - Other lease cost information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
LEASES
Cash paid for operating leases	$ 5,934	$ 2,936	$ 17,336	$ 8,850
Right-of-use assets obtained in exchange for operating lease liabilities	$ 9,586	$ 56,319	$ 34,064	$ 113,874
Weighted average remaining lease term (in years)	10 years 9 months 18 days	8 years 8 months 12 days	10 years 9 months 18 days	8 years 8 months 12 days
Weighted average discount rate	4.50%	4.00%	4.50%	4.00%

PENSION LIABILITY (Details)

PENSION LIABILITY (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 70,156	$ 68,359
Payments through April 30, 2024 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected future employer contributions	800
Payments from May 1, 2024 through November 30, 2033 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected future employer contributions	$ 1,700

PENSION LIABILITY - Components

PENSION LIABILITY - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
PENSION LIABILITY
Service Cost	$ 269	$ 124	$ 791	$ 124
Interest Cost	470	274	1,449	668
Expected return on plan assets	(151)	(160)	(441)	(496)
Amortization of actuarial gain and losses	116	90	344	323
Net periodic pension cost	$ 704	$ 328	$ 2,143	$ 619

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) shares in Millions	9 Months Ended
	Sep. 30, 2020shares
2017 OMNIBUS Incentive Plan [Member]
Shares reserved	2.8
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2
Restricted Stock Units (RSUs) [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted Stock Units (RSUs) [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Stock Option Awards [Member]
Awards term	10 years
Stock Option Awards [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Stock Option Awards [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of stock-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
STOCK-BASED COMPENSATION
Stock-based compensation expense	$ 3,781	$ 917	$ 9,666	$ 5,053

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of non-vested Restricted Stock Units activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at the beginning of period | shares	534
Granted | shares	336
Vested | shares	(150)
Forfeited | shares	(38)
Outstanding at the end of period | shares	682
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 56.56
Weighted Average Grant Date Fair Value, Granted | $ / shares	59.33
Weighted Average Grant Date Fair Value, Vested | $ / shares	57.16
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	59.38
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 57.97

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summary of stock option activity (Details) - Time Based [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at beginning of period | shares	185
Exercised | shares	(32)
Expired | shares	(4)
Outstanding at ending of period | shares	149
Weighted-Average Exercise Price Per Share, Beginning Balance | $ / shares	$ 21.56
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	13.39
Weighted-Average Exercise Price Per Share, Expired | $ / shares	15.58
Weighted-Average Exercise Price Per Share, End Balance | $ / shares	$ 23.48

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Sep. 30, 2020USD ($)
COMMITMENTS AND CONTINGENCIES
Purchase Commitment, Remaining Minimum Amount Committed	$ 178.1

RELATED PARTY TRANSACTIONS - Sa

RELATED PARTY TRANSACTIONS - Sales (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)customer	Sep. 30, 2019USD ($)customer	Sep. 30, 2020USD ($)customer	Sep. 30, 2019USD ($)customer	Dec. 31, 2019customer
RELATED PARTY TRANSACTIONS
Sales to related parties | $	$ 2	$ 287	$ 2	$ 1,299
Number of related party customers | customer	1	1	1	1	1

RELATED PARTY TRANSACTIONS - Ac

RELATED PARTY TRANSACTIONS - Accounts (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)customer	Sep. 30, 2019customer	Sep. 30, 2020USD ($)customer	Sep. 30, 2019customer	Dec. 31, 2019USD ($)customer
RELATED PARTY TRANSACTIONS
Accounts receivable from related parties	$ 2		$ 2
Number of related party customers | customer	1	1	1	1	1
Accounts payable with related parties	$ 0		$ 0		$ 0

SIGNIFICANT CUSTOMER INFORMAT_3

SIGNIFICANT CUSTOMER INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue, Major Customer [Line Items]
Sales, net	$ 389,521	$ 175,127	$ 1,044,857	$ 450,680
Product [Member]
Revenue, Major Customer [Line Items]
Sales, net	358,257	148,138	959,388	366,443
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Sales, net	$ 65,740	$ 38,957	$ 181,129	$ 108,978
Significant concentration risk, 10% or more of total balance	16.90%	22.20%	17.30%	24.20%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Lam Research [Member]
Revenue, Major Customer [Line Items]
Sales, net	$ 40,798	$ 21,991		$ 61,364
Significant concentration risk, 10% or more of total balance	10.50%	12.60%		13.60%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Significant concentration risk, 10% or more of total balance			16.20%		14.90%
Accounts receivable	$ 39,015		$ 39,015		$ 36,849
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Nidec Motor Corporation [Member]
Revenue, Major Customer [Line Items]
Significant concentration risk, 10% or more of total balance					15.40%
Accounts receivable					$ 38,071

CREDIT FACILITY (Details)

CREDIT FACILITY (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Line of Credit Facility [Line Items]
Fair value of long-term debt	$ 326,300
Long-term debt	$ 326,294	$ 339,027
Revolving Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity			$ 500,000
Unused line fee payment percentage	0.10%
Credit availability under the Loan Agreement	$ 150,000
Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity			350,000
Unsecured Revolving Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity			$ 150,000
Interest Rate Swap [Member]
Line of Credit Facility [Line Items]
Derivative, notional amount	$ 277,594

CREDIT FACILITY - Debt obligati

CREDIT FACILITY - Debt obligation (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt:
Term Loan Facility	$ 328,125	$ 341,250
Less: debt issuance costs	(1,831)	(2,223)
Total debt	326,294	339,027
Less current portion of long-term debt	(17,500)	(17,500)
Total long-term debt	$ 308,794	$ 321,527

CREDIT FACILITY - Contractual m

CREDIT FACILITY - Contractual maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
CREDIT FACILITY
2020 (remaining)	$ 4,375
2021	17,500
2022	17,500
2023	17,500
2024	271,250
Total	$ 328,125	$ 341,250

CREDIT FACILITY - Interest expe

CREDIT FACILITY - Interest expense and unused line of credit fees (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CREDIT FACILITY
Interest expense	$ 778	$ 703	$ 4,021	$ 703
Amortization of debt issuance costs	129	45	392	45
Unused line of credit fees and other	38	60	114	179
Total interest expense	$ 945	$ 808	$ 4,527	$ 927