Advanced Energy Industries (AEIS) 10-K 24 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 18, 2021	Jun. 30, 2020
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		38,300,076
Entity Central Index Key	0000927003
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2,563,579,586

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 480,368	$ 346,441
Marketable securities	2,654	2,614
Accounts and other receivable, net	235,178	246,564
Inventories	221,346	230,019
Income taxes receivable	4,804	4,245
Other current assets	35,899	36,855
Total current assets	980,249	866,738
Property and equipment, net	114,731	108,109
Operating lease right-of-use assets	103,858	105,404
Deposits and other assets	19,101	22,556
Goodwill	209,983	202,932
Intangible assets, net	168,939	184,011
Deferred income tax assets	50,801	42,656
TOTAL ASSETS	1,647,662	1,532,406
Current liabilities:
Accounts payable	125,224	170,671
Income taxes payable	11,850	9,687
Accrued payroll and employee benefits	63,487	51,545
Other accrued expenses	49,565	41,691
Customer deposits and other	12,179	10,926
Current portion of long-term debt	17,500	17,500
Current portion of operating lease liabilities	16,592	18,312
Total current liabilities	296,397	320,332
Long-term debt	304,546	321,527
Operating lease liabilities	95,993	90,538
Pension benefits	80,447	68,169
Deferred income tax liabilities	10,088	9,952
Uncertain tax positions	12,839	16,055
Long-term deferred revenue	7,352	8,011
Other long-term liabilities	24,660	20,562
Total liabilities	832,322	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; 38,293 and 38,358 issued and outstanding on December 31, 2020 and December 31, 2019, respectively	38	38
Additional paid-in capital	105,009	104,849
Accumulated other comprehensive loss	(2,605)	(5,897)
Retained earnings	712,297	577,724
Advanced Energy stockholders' equity	814,739	676,714
Noncontrolling interest	601	546
Total stockholders' equity	815,340	677,260
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,647,662	$ 1,532,406

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 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)	1,000,000	1,000,000
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)	38,293,000	38,358,000
Common stock, shares outstanding (in shares)	38,293,000	38,358,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Sales, net:
Total sales, net	$ 1,415,826	$ 788,948	$ 718,892
Cost of sales:
Total cost of sales	873,957	473,296	353,285
Gross profit	541,869	315,652	365,607
Operating expenses:
Research and development	143,961	101,503	76,008
Selling, general and administrative	188,590	142,555	108,033
Amortization of intangible assets	20,129	12,168	5,774
Restructuring expense	13,166	5,038	4,239
Total operating expenses	365,846	261,264	194,054
Operating income	176,023	54,388	171,553
Other income (expense), net	(17,876)	12,806	823
Income from continuing operations, before income taxes	158,147	67,194	172,376
Provision for income taxes	22,996	10,699	25,227
Income from continuing operations	135,151	56,495	147,149
Income (loss) from discontinued operations, net of income taxes	(421)	8,480	(38)
Net income	134,730	64,975	147,111
Income from continuing operations attributable to noncontrolling interest	55	34	86
Net income attributable to Advanced Energy Industries, Inc.	$ 134,675	$ 64,941	$ 147,025
Basic weighted-average common shares outstanding	38,314	38,281	39,081
Diluted weighted-average common shares outstanding	38,542	38,495	39,352
Earnings per share:
Continuing operations: Basic earnings per share	$ 3.53	$ 1.47	$ 3.76
Continuing operations: Diluted earnings per share	3.51	1.47	3.74
Discontinued operations: Basic earnings (loss) per share	(0.01)	0.22
Discontinued operations: Diluted earnings (loss) per share	(0.01)	0.22
Net income:
Basic earnings per share	3.52	1.70	3.76
Diluted earnings per share	$ 3.50	$ 1.69	$ 3.74
Product [Member]
Sales, net:
Total sales, net	$ 1,296,867	$ 678,061	$ 610,326
Cost of sales:
Total cost of sales	816,329	416,976	298,597
Services [Member]
Sales, net:
Total sales, net	118,959	110,887	108,566
Cost of sales:
Total cost of sales	$ 57,628	$ 56,320	$ 54,688

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income
Net income	$ 134,730	$ 64,975	$ 147,111
Other comprehensive income (loss), net of income taxes
Foreign currency translation	13,095	(2,523)	(5,285)
Change in fair value of cash flow hedges	(2,139)
Minimum benefit retirement liability	(7,664)	75	(697)
Comprehensive income	138,022	62,527	141,129
Comprehensive income attributable to noncontrolling interest	55	34	86
Comprehensive income attributable to Advanced Energy Industries, Inc.	$ 137,967	$ 62,493	$ 141,043

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Retained Earnings	Non-controlling Interest	Total
Adoption of new accounting standards				$ 32,533		$ 32,533
Beginning Balance at Dec. 31, 2017	$ 40	$ 184,843	$ 2,533	333,225		520,641
Beginning Balance (in shares) at Dec. 31, 2017	39,604,000
Non-controlling interest from acquisition					$ 426
Stock issued from equity plans		(2,005)				(2,005)
Stock issued from equity plans (in shares)	256,000
Stock-based compensation		9,703				9,703
Stock buyback	$ (2)	(95,123)				(95,125)
Stock buyback (in shares)	(1,696,000)
Other comprehensive income (loss)			(5,982)			(5,982)
Net income				147,025	86	147,111
Ending Balance at Dec. 31, 2018	$ 38	97,418	(3,449)	512,783	512	607,302
Ending Balance (in shares) at Dec. 31, 2018	38,164,000
Adoption of new accounting standards						426
Stock issued from equity plans		104				104
Stock issued from equity plans (in shares)	194,000
Stock-based compensation		7,327				7,327
Other comprehensive income (loss)			(2,448)			(2,448)
Net income				64,941	34	64,975
Ending Balance at Dec. 31, 2019	$ 38	104,849	(5,897)	577,724	546	$ 677,260
Ending Balance (in shares) at Dec. 31, 2019	38,358,000					38,358,000
Adoption of new accounting standards				(102)		$ (102)
Stock issued from equity plans		(482)				(482)
Stock issued from equity plans (in shares)	179,000
Stock-based compensation		12,272				12,272
Stock buyback		(11,630)				(11,630)
Stock buyback (in shares)	(244,000)
Other comprehensive income (loss)			3,292			3,292
Net income				134,675	55	134,730
Ending Balance at Dec. 31, 2020	$ 38	$ 105,009	$ (2,605)	$ 712,297	$ 601	$ 815,340
Ending Balance (in shares) at Dec. 31, 2020	38,293,000					38,293,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 134,730	$ 64,975	$ 147,111
Income (loss) from discontinued operations, net of income taxes	(421)	8,480	(38)
Income from continuing operations, net of income taxes	135,151	56,495	147,149
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	47,770	26,147	13,592
Stock-based compensation expense	12,272	7,327	9,703
Provision (benefit) for deferred income taxes	(622)	1,015	5,618
Gain on sale of central inverter service business		(14,795)
Discount on notes receivable	721	1,100
Net loss on disposal of assets	1,296	700	481
Changes in operating assets and liabilities, net of assets acquired:
Accounts and other receivable, net	15,412	(18,879)	3,445
Inventories	11,658	3,687	(11,276)
Other assets	1,750	23,544	(2,975)
Accounts payable	(48,163)	(16,094)	(12,618)
Other liabilities and accrued expenses	24,520	(12,486)	(3,239)
Income taxes	394	(9,862)	1,547
Net cash from operating activities from continuing operations	202,159	47,899	151,427
Net cash from operating activities from discontinued operations	(923)	493	(156)
Net cash from operating activities	201,236	48,392	151,271
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sale of marketable securities	3	1,742	494
Acquisitions, net of cash acquired	(5,476)	(366,101)	(93,756)
Issuance of notes receivable	(1,000)	(4,300)
Proceeds from sale of property and equipment	116
Purchases of property and equipment	(36,483)	(25,188)	(20,330)
Net cash from investing activities from continuing operations	(42,840)	(393,847)	(113,592)
Net cash from investing activities	(42,840)	(393,847)	(113,592)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from long-term borrowings		347,486
Payments on long-term borrowings	(17,500)	(8,750)
Purchase and retirement of common stock	(11,630)		(95,125)
Net receipts (payments) related to stock-based award activities	(482)	104	(2,009)
Net cash from financing activities from continuing operations	(29,612)	338,840	(97,134)
Net cash from financing activities	(29,612)	338,840	(97,134)
EFFECT OF CURRENCY TRANSLATION ON CASH	5,143	(1,496)	(1,030)
NET CHANGE IN CASH AND CASH EQUIVALENTS	133,927	(8,111)	(60,485)
CASH AND CASH EQUIVALENTS, beginning of period	346,441	354,552	415,037
CASH AND CASH EQUIVALENTS, end of period	480,368	346,441	354,552
Less cash and cash equivalents from discontinued operations			5,251
CASH AND CASH EQUIVALENTS FROM CONTINUING OPERATIONS, end of period	480,368	346,441	349,301
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	5,278	3,479	228
Cash paid for income taxes	21,032	18,594	16,190
Cash received for refunds of income taxes	$ 1,569	$ 1,762	$ 1,135

OPERATIONS AND SUMMARY OF SIGNI

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES	12 Months Ended
	Dec. 31, 2020
OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES
OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES	NOTE 1. OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES 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, 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. We operate in a single segment structure for power electronics conversion products and we operate in four vertical markets or applications to enable tracking of market trends. 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, 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 Artesyn Embedded Technologies, Inc.’s embedded power business ("Artesyn") Note 4. Disposed and Discontinued Operations Principles of Consolidation Use of Estimates in the Preparation of the Consolidated Financial Statements — Foreign Currency Translation — For certain other subsidiaries, the functional currency is the U.S. Dollar. Foreign currency transactions are recorded based on exchange rates at the time such transactions arise. Subsequent changes in exchange rates for foreign currency denominated monetary assets and liabilities result in foreign currency transaction gains and losses which are reflected as unrealized (based on period end remeasurement) or realized (upon settlement of the transactions) in Other income (expense), net in our Consolidated Statements of Operations. 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 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 — 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 on 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 21. Credit Facility Cash, Cash Equivalents, and Marketable Securities Sometimes we invest excess cash in money market funds not insured by the Federal Deposit Insurance Corporation. We believe that the investments in money market funds are on deposit with credit-worthy financial institutions and that the funds are highly liquid. The investments in money market funds are reported at fair value, with interest income recorded in earnings and are included in "Cash and cash equivalents." Concentrations of Credit Risk — We have established a reserve for credit losses based upon factors surrounding the credit risk of specific customers, historical trends, and other information. Accounts Receivable and Reserve for Credit Losses — Our principal customers are original equipment manufacturers ("OEM") 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, we assess credit risks as a single group. We evaluate collection risk and establish 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. Inventories We regularly review inventory quantities on hand and record a provision to write-down excess and obsolete inventory to its estimated net realizable value, if less than cost, based primarily on historical usage and our estimated forecast of product demand. Demand for our products can fluctuate significantly. A significant decrease in demand could result in an increase in the charges for excess inventory quantities on hand. In addition, our industry is subject to technological change, new product development, and product technological obsolescence that could result in an increase in the amount of obsolete inventory quantities on hand. Therefore, any significant unanticipated changes in demand or technological developments could have a significant impact on the value of our inventory and our reported operating results. Property and Equipment 3 Amortization of leasehold improvements is calculated using the straight-line method over the lease term or the estimated useful life of the assets, whichever period is shorter. Leasehold additions and improvements are capitalized, while maintenance and repairs are expensed as incurred. When depreciable assets are retired, or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any related gains or losses are included in Other income (expense), net, in our Consolidated Statements of Operations. Purchase accounting Intangible Assets, Goodwill and Other Long-Lived Assets The estimation of useful lives and expected cash flows requires us to make judgments regarding future periods that are subject to some factors outside of our control. Changes in these estimates can result in revisions to our carrying value of these assets and may result in material charges to our results of operations. The annual impairment test for goodwill can be performed using an assessment of qualitative factors in determining if it is more likely than not that goodwill is impaired. If this assessment indicates that it is more likely than not that goodwill is impaired, the next step of impairment testing compares the fair value of a reporting unit to its carrying value. Goodwill would be impaired if the resulting implied fair value of goodwill was less than the recorded carrying value of the goodwill. Debt Issuance Costs Note 21. Credit Facility Revenue Recognition We maintain a worldwide support organization in ten countries, including the United States, the Peoples Republic of China ("PRC"), Japan, Korea, Taiwan, Germany, Ireland, Singapore, Israel, and Great Britain. 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. As part of our ongoing service business, we satisfy our service obligations under extended warranties and preventive maintenance contracts. Extended warranties had previously been offered on our discontinued inverter products. Any up-front fees received for extended warranties or maintenance plans are deferred and recognized ratably over the service periods, as defined in the agreements. Research and Development Expenses Warranty Costs 12 five Note 4. Disposed and Discontinued Operations Note 15. Warranties Stock-Based Compensation Income Taxes We assess the recoverability of our net deferred tax assets and the need for a valuation allowance on a quarterly basis. Our assessment includes several factors including historical results and taxable income projections for each jurisdiction. The ultimate realization of deferred income tax assets is dependent on the generation of taxable income in appropriate jurisdictions during the periods in which those temporary differences are deductible. We consider the scheduled reversal of deferred income tax liabilities, projected future taxable income, and tax planning strategies in determining the amount of the valuation allowance. Based on the level of historical taxable income and projections for future taxable income over the periods in which the deferred income tax assets are deductible, we determine if we will realize the benefits of these deductible differences. Accounting for income taxes requires a two-step approach to recognize and measure uncertain tax positions. In general, we are subject to regular examination of our income tax returns by the Internal Revenue Service and other tax authorities. The first step is to evaluate the tax position for recognition by determining, if based on the technical merits, it is more likely than not that the position will be sustained upon audit, including resolutions of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement. We regularly assess the likelihood of favorable or unfavorable outcomes resulting from these examinations to determine the adequacy of our provision for income taxes. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. On December 22, 2017, the Tax Act was enacted into law and the new legislation contains several key tax provisions that affected us, including a one-time mandatory transition tax on accumulated foreign earnings and a reduction of the corporate income tax rate to 21%, among others. In conjunction with the Tax Act enactment, the SEC issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act Under U.S. GAAP, an accounting policy election can be made to either recognize deferred taxes for temporary basis differences expected to reverse as global intangible low-tax income ("GILTI") in future years, or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. We have elected to account for GILTI in the year the tax is incurred. Leases Right-of-use assets and operating lease liabilities are recognized at the present value of the future lease payments on the lease commencement date. The interest rate used to determine the present value of the future lease payments is our incremental borrowing rate, because the interest rate implicit in our leases is not readily determinable. Our incremental borrowing rate is estimated to approximate the interest rate on a collateralized basis with similar terms and payments. Our lease terms include periods under options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Right-of-use assets also include any prepaid lease payments and lease incentives. Operating lease expense is recognized on a straight-line basis over the lease term. Commitments and Contingencies NEW ACCOUNTING STANDARDS New Accounting Standards Adopted In December 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes" ​ In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820)" In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" New Accounting Standards In August 2018, the FASB issued ASU 2018-14, "Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20)" effective for interim and annual periods 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"

BUSINESS ACQUISITIONS

BUSINESS ACQUISITIONS	12 Months Ended
	Dec. 31, 2020
BUSINESS ACQUISITIONS
BUSINESS ACQUISITIONS	NOTE 2. BUSINESS ACQUISITIONS Versatile Power, Inc On December 31, 2020, we acquired 100% of the issued and outstanding shares of Versatile Power, Inc., which is based in Campbell, California. This acquisition added radio frequency ("RF") and programmable power supplies for medical and industrial applications to our product portfolio and further expands our presence in the medical market by adding proven technologies, deep customer relationships, expertise in medical design, and a medical-certified manufacturing center. The components of the fair value of the total consideration transferred are as follows: ​ ​ ​ ​ ​ Cash paid for acquisition $ 4,594 Holdback ​ ​ 950 Contingent consideration ​ ​ 1,500 Total fair value of consideration transferred ​ ​ 7,044 Less cash acquired ​ ​ (245) Total purchase price ​ $ 6,799 ​ The following table summarizes the estimated preliminary values of the assets acquired and liabilities assumed: ​ ​ ​ ​ ​ ​ Preliminary Current asset and liabilities, net ​ $ 1,015 Property and equipment ​ ​ 35 Operating lease right-of-use assets ​ ​ 453 Intangible assets ​ ​ 4,000 Goodwill ​ ​ 1,749 Total assets acquired ​ ​ 7,252 Operating lease liability ​ ​ 453 Total liabilities assumed ​ ​ 453 Total fair value of net assets acquired ​ $ 6,799 ​ Artesyn’s Embedded Power Business In September 2019, we completed the acquisition of Artesyn Embedded Technologies, Inc.’s 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 100% 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. See Note 21. Credit Facility 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, such as data centers (including 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 are 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: ​ ​ ​ ​ ​ ​ Final Fair 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 ​ 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 on 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. Advanced Energy settled the adjustment for the 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 Transaction 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 on January 1, 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 year ended December 31, 2019 combines Advanced Energy’s results with the pre-acquisition results of Artesyn for that period. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2019 ​ As Reported Pro Forma Total sales $ 788,948 $ 1,202,790 Net income attributable to Advanced Energy Industries, Inc. $ 64,941 $ 83,104 Earnings per share: ​ ​ ​ ​ Basic earnings per share ​ $ 1.70 ​ $ 2.17 Diluted earnings per share ​ $ 1.69 ​ $ 2.16 ​ 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 subsequent to the completion of the acquisition on September 10, 2019. During the year ended December 31, 2019, Artesyn contributed total sales of $220.3 million and net income of $7.1 million, including interest and other expense associated with the financing of the transaction.

REVENUE

REVENUE	12 Months Ended
	Dec. 31, 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. 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 Computing (including hyperscale), and Industrial and Medical 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 OEMs and end customers in the semiconductor, flat panel display, high voltage, solar panel, Telecom and Networking, Data Center Computing, Industrial and Medical 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, such as 5G, data center (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 in ten countries, including the United States, the PRC, Japan, Korea, Taiwan, Germany, Ireland, Singapore, Israel, and Great Britain. Support services include warranty and non-warranty repair services, upgrades, and refurbishments on the products we sell. 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 ​ Semiconductor Equipment ​ $ 611,864 ​ $ 403,018 ​ $ 533,770 ​ Industrial and Medical ​ 313,646 ​ 245,992 ​ 185,122 ​ Data Center Computing ​ ​ 322,539 ​ ​ 91,438 ​ ​ — ​ Telecom and Networking ​ ​ 167,777 ​ ​ 48,500 ​ ​ — Total ​ $ 1,415,826 ​ $ 788,948 ​ $ 718,892 ​ ​ The following table presents our sales by geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 North America ​ $ 687,814 48.6 % $ 373,634 47.4 % $ 372,834 51.8 % Asia ​ 606,893 42.9 ​ 295,155 37.4 ​ 250,574 34.9 ​ Europe ​ 117,990 8.3 ​ 119,427 15.1 ​ 94,793 13.2 ​ Other ​ 3,129 0.2 ​ 732 0.1 ​ 691 0.1 ​ Total ​ $ 1,415,826 100.0 % $ 788,948 100.0 % $ 718,892 100.0 % ​ 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Product and service revenue recognized at point in time ​ $ 1,414,982 ​ $ 786,918 ​ $ 715,055 Extended warranty and service contracts recognized over time ​ 844 ​ 2,030 ​ 3,837 Total ​ $ 1,415,826 ​ $ 788,948 ​ $ 718,892 ​

DISPOSED AND DISCONTINUED OPERA

DISPOSED AND DISCONTINUED OPERATIONS	12 Months Ended
	Dec. 31, 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Sales ​ $ — ​ $ — Cost of sales ​ — ​ (901) Total operating expense ​ 620 ​ 1,022 Operating income (loss) from discontinued operations ​ (620) ​ (121) Other income (expense) ​ 65 ​ 10,895 Income (loss) from discontinued operations before income taxes ​ (555) ​ 10,774 Provision (benefit) for income taxes ​ (134) ​ 2,294 Income (loss) from discontinued operations, net of income taxes ​ $ (421) ​ $ 8,480 ​ Assets and Liabilities of discontinued operations are not significant.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
INCOME TAXES	NOTE 5. INCOME TAXES The geographic distribution of pretax income from continuing operations is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Domestic ​ $ 17,526 ​ $ (20,597) ​ $ 22,325 Foreign ​ 140,621 ​ 87,791 ​ 150,051 ​ ​ $ 158,147 ​ $ 67,194 ​ $ 172,376 ​ The provision for income taxes from continuing operations is summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Current: ​ ​ ​ Federal ​ $ 5,475 ​ $ (9,627) ​ $ 1,423 State ​ 1,927 ​ 882 ​ 12 Foreign ​ 16,216 ​ 18,429 ​ 13,772 Total current provision ​ $ 23,618 ​ $ 9,684 ​ $ 15,207 Deferred: ​ ​ ​ Federal ​ $ (312) ​ $ 3,822 ​ $ 4,021 State ​ 1,270 ​ (178) ​ 2,363 Foreign ​ (1,580) ​ (2,629) ​ 3,636 Total deferred provision (benefit) ​ (622) ​ 1,015 ​ 10,020 Total provision for income taxes ​ $ 22,996 ​ $ 10,699 ​ $ 25,227 ​ The Company’s effective tax rates differ from the U.S. federal statutory rate of 21% for the three years ended December 31, 2020 primarily due to the benefit of earnings in foreign jurisdictions which are subject to lower tax rates, offset by net U.S. tax on foreign operations and withholding taxes. The principal causes of the difference between the federal statutory rate and the effective income tax rate for each of the years below are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Income taxes per federal statutory rate ​ $ 33,211 ​ $ 14,111 ​ $ 36,199 State income taxes, net of federal deduction ​ ​ 2,793 ​ ​ 10 ​ ​ 2,372 U.S. tax on foreign operations ​ ​ 9,666 ​ ​ 5,805 ​ ​ 6,943 Foreign derived intangible income deduction ​ ​ (4,070) ​ ​ – ​ ​ (261) Tax effect of foreign operations ​ ​ (20,527) ​ ​ (13,086) ​ ​ (19,162) Uncertain tax position ​ ​ (3,215) ​ ​ (4,487) ​ ​ (3,088) Unremitted earnings ​ ​ (567) ​ ​ 1,624 ​ ​ 2,564 Tax credits ​ ​ (2,292) ​ ​ (2,088) ​ ​ (1,484) Change in valuation allowance ​ ​ (1,175) ​ ​ 7,222 ​ ​ (1,306) Withholding taxes ​ ​ 4,265 ​ ​ 6,500 ​ ​ 1,371 Other permanent items, net ​ ​ 4,907 ​ ​ (4,912) ​ ​ 1,079 Total provision for income taxes ​ $ 22,996 ​ $ 10,699 ​ $ 25,227 ​ Deferred tax assets and liabilities are recognized for the future tax consequences of differences between the carrying amounts of assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to be reversed. Significant deferred tax assets and liabilities consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Deferred tax assets ​ ​ Stock-based compensation ​ $ 2,130 ​ $ 1,757 Net operating loss and tax credit carryforwards ​ 57,590 ​ 86,879 Interest expense limitation ​ ​ 7,344 ​ ​ 7,620 Pension obligation ​ 14,297 ​ 13,473 Excess and obsolete inventory ​ 3,722 ​ 3,217 Accrued restructuring ​ ​ 2,468 ​ ​ — Deferred revenue ​ 3,048 ​ 3,305 Employee bonuses and commissions ​ 5,388 ​ 2,537 Depreciation and amortization ​ 28,786 ​ 29,015 Operating lease liabilities ​ ​ 20,267 ​ ​ 23,451 Other ​ 8,925 ​ 9,685 Deferred tax assets ​ 153,965 ​ 180,939 Less: Valuation allowance ​ (46,702) ​ (76,206) Net deferred tax assets ​ 107,263 ​ 104,733 Deferred tax liabilities ​ ​ Depreciation and amortization ​ 40,266 ​ 41,549 Unremitted earnings ​ 4,173 ​ 4,740 Operating lease right-of-use assets ​ ​ 18,731 ​ ​ 22,774 Other ​ 3,380 ​ 2,966 Deferred tax liabilities ​ 66,550 ​ 72,029 Net deferred tax assets ​ $ 40,713 ​ $ 32,704 ​ Of the $40.7 million and $32.7 million net deferred tax asset on December 31, 2020 and 2019, respectively, $50.8 million and $42.7 million is reflected as a net non-current deferred tax asset and $10.1 million and $10.0 million is reflected as a long-term liability on December 31, 2020 and 2019, respectively. As of December 31, 2020, the Company has recorded a valuation allowance on $4.2 million of its U.S. domestic deferred tax assets, largely attributable to state carryforward attributes that are expected to expire before sufficient income can be realized in those jurisdictions. The remaining valuation allowance on deferred tax assets approximates $42.5 million and is associated primarily with operations in Germany, Hong Kong, and Switzerland. As of December 31, 2020, there is not sufficient positive evidence to conclude that such deferred tax assets, presently reduced by a valuation allowance, will be recognized. The December 31, 2020 valuation allowance balance reflects a decrease of $29.5 million during the year. The change in the valuation allowance is primarily due to the dissolution of an Austrian entity, refinements in the determination of Artesyn attributes acquired in 2019, and the netting of Section 382 limited attributes that will never be available for utilization with their valuation allowance, partially offset by increases due to foreign exchange movements. As of December 31, 2020, the Company had U.S., foreign and state tax loss carryforwards of $70.3 million, $129.6 million, and $117.7 million, respectively. Additionally, the Company had $0.2 million and $30.5 million of capital loss and interest expense limitation carryforwards, respectively. Finally, the Company had U.S. and state tax credit carryforwards of $1.3 million and $1.7 million, respectively. The U.S. and state net operating losses, tax credits, and interest expense limitation are subject to various utilization limitations under Section 382 of the Internal Revenue Code and applicable state laws. These Section 382 limited attributes have various expiration periods through 2036 or, in the case of the interest expense limitation amount, no expiration period. Much of the foreign jurisdiction, and $8.0 million of the federal net operating loss carry forwards, have no expiration period. We operate under a tax holiday in Singapore and China. These tax holidays are in effect through June 30, 2027 and December 31, 2022, respectively. The tax holiday is conditional upon our meeting certain employment and investment thresholds. The impact of the tax holidays decreased foreign taxes by $13.0 million and $4.0 million for 2020 and 2019, respectively. The benefit of the tax holiday on earnings per diluted share was $0.34 and $0.12 for 2020 and 2019, respectively. As of December 31, 2020, we have undistributed earnings of certain foreign subsidiaries of approximately $58.9 million that we have indefinitely invested, and on which we have not recognized deferred taxes. Estimating the amount of potential tax is not practicable because of the complexity and variety of assumptions necessary to compute the tax. We account for uncertain tax positions by applying a minimum recognition threshold to tax positions before recognizing these positions in the financial statements. The reconciliation of our total gross unrecognized tax benefits is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Balance at beginning of period ​ $ 13,009 ​ $ 13,162 ​ $ 15,990 Additions based on tax positions taken during a prior period ​ 219 ​ 484 ​ 94 Additions based on tax positions taken during a prior period – acquisitions ​ — ​ 4,479 ​ 757 Additions based on tax positions taken during the current period ​ — ​ — ​ — Reductions based on tax positions taken during a prior period ​ — ​ (4,295) ​ (153) Reductions related to a lapse of applicable statute of limitations ​ (3,555) ​ (821) ​ (3,144) Reductions related to a settlement with taxing authorities ​ — ​ — ​ (382) Balance at end of period ​ $ 9,673 ​ $ 13,009 ​ $ 13,162 ​ The unrecognized tax benefits of $9.7 million, if recognized, will impact the Company’s effective tax rate. In accordance with our accounting policy, we recognize accrued interest and penalties related to unrecognized tax benefits as a component of tax expense. We had $3.2 million and $3.0 million of accrued interest and penalties on December 31, 2020 and 2019, respectively. We expect the total amount of tax contingencies will decrease by approximately $3.5 million in 2021 based on statute of limitation expiration. With few exceptions, the Company is no longer subject to federal, state, or foreign income tax examinations by tax authorities for years before 2017.

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 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 earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Income from continuing operations ​ $ 135,151 ​ $ 56,495 ​ $ 147,149 Income from continuing operations attributable to noncontrolling interest ​ 55 ​ 34 ​ 86 Income from continuing operations attributable to Advanced Energy Industries, Inc. ​ $ 135,096 ​ $ 56,461 ​ $ 147,063 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted-average common shares outstanding ​ 38,314 ​ 38,281 ​ 39,081 Assumed exercise of dilutive stock options and restricted stock units ​ 228 ​ 214 ​ 271 Diluted weighted-average common shares outstanding ​ 38,542 ​ 38,495 ​ 39,352 Continuing operations: ​ ​ ​ Basic earnings per share ​ $ 3.53 ​ $ 1.47 ​ $ 3.76 Diluted earnings per share ​ $ 3.51 ​ $ 1.47 ​ $ 3.74 ​ The following stock options and restricted units were excluded in the computation of diluted earnings per share because they were anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Restricted stock units — — 2 ​ Share Repurchase In September 2015, our Board of Directors authorized a program to repurchase up to $150.0 million of our common 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 our 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 December 31, 2020, the Company is authorized for the future repurchase of shares of our common stock of up to a total of $38.4 million. 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (in thousands, except per share amounts) 2020 2019 2018 Amount paid to repurchase shares ​ $ 11,630 ​ $ — ​ $ 95,125 Number of shares repurchased ​ 244 ​ — ​ 1,696 Average repurchase price per share ​ $ 47.75 ​ $ — ​ $ 56.07 ​ ​ ​ ​ ​ 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	12 Months Ended
	Dec. 31, 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. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 Description ​ Balance Sheet Classification ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ — ​ $ 2,654 ​ $ — ​ $ 2,654 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,654 ​ $ — ​ $ 2,654 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other current liabilities ​ $ — ​ $ — ​ $ 2,009 ​ $ 2,009 Contingent consideration ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 2,940 ​ ​ 2,940 Interest rate swaps ​ Other long-term liabilities ​ ​ — ​ ​ 2,811 ​ ​ — ​ ​ 2,811 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,811 ​ $ 4,949 ​ $ 7,760 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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	12 Months Ended
	Dec. 31, 2020
DERIVATIVE FINANCIAL INSTRUMENTS
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 December 31, 2020, and 2019, we did not have any currency exchange rate contracts outstanding. 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 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Interest rate swap contracts ​ $ 273,219 ​ $ — ​ On December 31, 2020, Accumulated other comprehensive loss on the Consolidated Balance Sheets includes $2.1 million, net of tax, related to changes in fair value on the interest rate swap contracts. 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, NET	12 Months Ended
	Dec. 31, 2020
ACCOUNTS AND OTHER RECEIVABLE, NET
ACCOUNTS AND OTHER RECEIVABLE, NET	NOTE 9. ACCOUNTS AND OTHER RECEIVABLE, NET Accounts and other receivable are recorded at net realizable value. Components of accounts and other receivable, net of reserves, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Amounts billed, net ​ $ 213,560 ​ $ 227,528 Unbilled receivables ​ ​ 21,618 ​ 19,036 Total receivables, net ​ $ 235,178 ​ $ 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: ​ ​ ​ ​ ​ Balance as of December 31, 2019 $ 7,745 Additions ​ 368 Deductions - write-offs, net of recoveries ​ (511) Balance as of December 31, 2020 ​ $ 7,602 ​

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Parts and raw materials ​ $ 141,337 ​ $ 134,816 Work in process ​ 13,702 ​ 10,269 Finished goods ​ 66,307 ​ 84,934 Total ​ $ 221,346 ​ $ 230,019 ​

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET	12 Months Ended
	Dec. 31, 2020
PROPERTY AND EQUIPMENT, NET
PROPERTY AND EQUIPMENT, NET	NOTE 11. PROPERTY AND EQUIPMENT, NET Property and equipment, net is comprised of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Buildings and land ​ $ 1,776 ​ $ 1,693 Machinery and equipment ​ 115,404 ​ 108,945 Computer and communication equipment ​ 26,623 ​ 29,106 Furniture and fixtures ​ 4,352 ​ 4,119 Vehicles ​ 262 ​ 262 Leasehold improvements ​ 42,984 ​ 33,041 Construction in process ​ 3,693 ​ 9,089 ​ ​ 195,094 ​ 186,255 Less: Accumulated depreciation ​ (80,363) ​ (78,146) Property and equipment, net ​ $ 114,731 ​ $ 108,109 ​ The following table summarizes depreciation expense. All depreciation expense is recorded in income from continuing operations. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Depreciation expense ​ $ 27,641 ​ $ 13,979 ​ $ 7,818 ​

GOODWILL

GOODWILL	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
GOODWILL	NOTE 12. GOODWILL The following table summarizes the changes in goodwill: ​ ​ ​ ​ ​ Balance as of December 31, 2018 ​ $ 101,900 Measurement period adjustments to purchase price allocation ​ ​ (41,996) Additions from acquisition ​ ​ 143,262 Foreign currency translation ​ ​ (234) Balance as of December 31, 2019 $ 202,932 Measurement period adjustments to purchase price allocation ​ ​ 1,957 Additions from acquisition ​ ​ 1,749 Foreign currency translation ​ ​ 3,345 Balance as of December 31, 2020 ​ $ 209,983 ​ Additions and adjustments are the result of finalizing the Artesyn acquisition and other allocations. Refer to Note 2. Business Acquisitions.

INTANGIBLE ASSETS

INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
INTANGIBLE ASSETS	NOTE 13. INTANGIBLE ASSETS Intangible assets consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying December 31, 2020 ​ Amount ​ Amortization ​ Amount Technology ​ $ 85,075 ​ $ (24,999) ​ $ 60,076 Customer relationships ​ 114,171 ​ (26,880) ​ 87,291 Trademarks and other ​ 27,021 ​ (5,449) ​ 21,572 Total ​ $ 226,267 ​ $ (57,328) ​ $ 168,939 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ At December 31, 2020, the weighted average remaining useful life of intangibles subject to amortization was approximately 10.5 years. Amortization expense related to intangible assets is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Amortization expense ​ $ 20,129 ​ $ 12,168 ​ $ 5,774 ​ Estimated amortization expense related to intangibles is as follows: ​ ​ ​ ​ ​ Year Ending December 31, ​ ​ 2021 ​ $ 20,565 2022 ​ 20,276 2023 ​ 20,257 2024 ​ 17,334 2025 ​ 12,822 Thereafter ​ 77,685 Total ​ $ 168,939 ​

RESTRUCTURING COSTS

RESTRUCTURING COSTS	12 Months Ended
	Dec. 31, 2020
RESTRUCTURING COSTS
RESTRUCTURING COSTS	NOTE 14. RESTRUCTURING COSTS During 2018, 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 year ended December 31, 2020, we incurred severance costs primarily related to the transition and exit of our facility in Shenzhen, PRC, and actions associated with synergies related to the Artesyn acquisition. The table below summarizes the restructuring charges: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Cost ​ ​ Years Ended December 31, ​ Through December 31, ​ ​ 2020 2019 2018 2020 Severance and related charges $ 9,632 ​ $ 3,042 ​ $ 4,239 ​ $ 16,913 Facility relocation and closure charges ​ 3,534 ​ 1,996 ​ — ​ 5,530 Total restructuring charges ​ $ 13,166 ​ $ 5,038 ​ $ 4,239 ​ $ 22,443 ​ The following table summarizes our restructuring liabilities on December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred ​ Cost Paid ​ Effect of ​ ​ ​ ​ ​ Balance at ​ and ​ or ​ Changes in ​ Balance at ​ ​ December 31, ​ Charged to ​ Otherwise ​ Exchange ​ December 31, ​ ​ 2019 ​ Expense ​ Settled ​ Rates ​ 2020 Total restructuring liabilities ​ $ 2,172 ​ $ 13,166 ​ $ (4,714) ​ $ 17 ​ $ 10,641 ​ ​ ​ ​ ​ As of December 31, 2020, and 2019, the accrued restructuring liabilities related primarily to severance and related charges.

WARRANTIES

WARRANTIES	12 Months Ended
	Dec. 31, 2020
WARRANTIES
WARRANTIES	NOTE 15. WARRANTIES Provisions of our sales agreements include customary product warranties, ranging from 12 months to 24 months after shipment. 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 Consolidated Balance Sheets. Changes in our product warranty obligation are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Balances at beginning of period ​ $ 6,413 ​ $ 2,084 ​ $ 2,312 Warranty acquired in business combinations ​ 15 ​ 4,818 ​ 305 Increases to accruals ​ 2,996 ​ 1,752 ​ 1,606 Warranty expenditures ​ (4,688) ​ (2,249) ​ (2,127) Effect of changes in exchange rates ​ 44 ​ 8 ​ (12) Balances at end of period ​ $ 4,780 ​ $ 6,413 ​ $ 2,084 ​

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
LEASES
LEASES	NOTE 16. LEASES The Company leases 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Operating lease cost ​ $ 22,920 ​ $ 11,052 Short-term and variable lease cost ​ ​ 1,895 ​ ​ 4,726 Total operating lease cost ​ $ 24,815 ​ $ 15,778 ​ Maturities of our operating lease liabilities on December 31, 2020 are as follows: ​ ​ ​ ​ ​ Year Ending December 31, ​ 2021 ​ $ 21,126 2022 ​ 16,177 2023 ​ 12,979 2024 ​ 11,593 2025 ​ ​ 10,133 Thereafter ​ ​ 74,635 Total lease payments ​ ​ 146,643 Less: Interest ​ ​ (34,058) Present value of lease liabilities ​ $ 112,585 ​ We have one lease agreement that commences in March 2021 with total payments of $3.5 million over five years . Other information related to leases, including supplemental cash flow information, consists of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 ​ Weighted average remaining lease term (in years) ​ ​ 10.65 ​ ​ 7.50 ​ Weighted average discount rate ​ ​ 4.63 % ​ 4.05 % Cash paid for operating lease liabilities ​ $ 21,877 ​ $ 12,101 ​ Right-of-use assets obtained in exchange for operating lease liabilities (1) ​ $ 33,741 ​ $ 84,551 ​ (1) Included in 2019 are the right-of-use assets of $60.1 million obtained in connection with the acquisition of Artesyn in September 2019. Subsequent measurement period adjustments that occurred in the year ended December 31, 2020 reduced this amount to $54.4 million. See Note 2. Business Acquisitions for more details.

EMPLOYEE RETIREMENT PLANS AND P

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS	12 Months Ended
	Dec. 31, 2020
EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS
EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS	NOTE 17. EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS Defined Contribution Plans We have a 401(k) profit-sharing and retirement savings plan covering substantially all full-time U.S. employees. Participants may defer up to the maximum amount allowed as determined by law. Participants are immediately vested in their contributions. Profit-sharing contributions to the plan, which are discretionary, are approved by the Board of Directors. Vesting in the profit-sharing contribution account is based on years of service, with most participants fully vested after four years of credited service. For the years ended December 31, 2020, 2019, and 2018 our contribution for participants in our 401(k) plan was based on matching 50% of contributions made by employees up to 6% of the employee’s compensation. During the years ended December 31, 2020, 2019, and 2018 we recognized total defined contribution plan costs of $2.6 million, $1.6 million, and $1.4 million, respectively. Defined Benefit Plan We maintain defined benefit pension plans for certain of our non-U.S. employees in the U.K., Germany, and Philippines. Each plan is managed locally and in accordance with respective local laws and regulations. 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. The information provided below includes one pension plan which is part of discontinued operations. As such, all related liabilities and expenses are reported in discontinued operations in the Company’s Consolidated Balance Sheets and Consolidated Statements of Operations for all periods presented. The Company’s projected benefit obligation and plan assets for defined benefit pension plans and the related assumptions used to determine the related liabilities are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Projected benefit obligation, beginning of year ​ $ 83,262 ​ $ 33,178 Acquisition ​ — ​ 48,350 Service cost ​ 1,068 ​ 272 Interest cost ​ 1,716 ​ 1,211 Actuarial (gain) loss ​ 7,591 ​ (193) Benefits paid ​ (1,199) ​ (1,779) Translation adjustment ​ 5,302 ​ 2,223 Projected benefit obligation, end of year ​ ​ 97,740 ​ ​ 83,262 ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets, beginning of year ​ ​ 14,903 ​ ​ 13,433 Acquisitions ​ — ​ 102 Actual return on plan assets ​ 682 ​ 380 Contributions ​ 1,827 ​ 644 Benefits paid ​ (993) ​ (1,176) Actuarial gain ​ 180 ​ 1,064 Translation adjustment ​ 694 ​ 456 Fair value of plan assets, end of year ​ ​ 17,293 ​ ​ 14,903 Funded status of plan ​ $ (80,447) ​ $ (68,359) ​ The components of net periodic pension benefit cost recognized in our Consolidated Statements of Operations for the periods presented are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Service cost ​ $ 1,068 ​ $ 272 ​ $ 841 Interest cost ​ ​ 1,716 ​ ​ 1,211 ​ ​ 802 Expected return on plan assets ​ (683) ​ (615) ​ (665) Amortization of actuarial gains and losses ​ 459 ​ 411 ​ 478 Net periodic pension cost ​ $ 2,560 ​ $ 1,279 ​ $ 1,456 ​ Assumptions used in the determination of the net periodic pension cost are: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Discount rate 1.8 % 2.7 % 2.8 % Expected long-term return on plan assets 3.7 % 4.6 % 4.8 % ​ The fair value of the Company’s qualified pension plan assets by category are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ Level 1 Level 2 Level 3 Total Multi-Asset Fund ​ $ — ​ $ 5,149 ​ $ — ​ $ 5,149 Diversified Growth Fund ​ — ​ 5,134 ​ — ​ 5,134 Corporate Bonds ​ — ​ 4,906 ​ — ​ 4,906 Insurance Contracts ​ ​ — ​ — ​ 1,109 ​ 1,109 Cash ​ 995 ​ — ​ — ​ 995 Total ​ $ 995 ​ $ 15,189 ​ $ 1,109 ​ $ 17,293 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ Level 1 Level 2 Level 3 Total Multi-Asset Fund ​ $ — ​ $ 4,825 ​ $ — ​ $ 4,825 Diversified Growth Fund ​ — ​ 4,855 ​ — ​ 4,855 Index-Linked Gilts ​ — ​ 1,934 ​ — ​ 1,934 Corporate Bonds ​ — ​ 2,090 ​ — ​ 2,090 Insurance Contracts ​ ​ — ​ ​ — ​ ​ 1,045 ​ ​ 1,045 Cash ​ 154 ​ — ​ — ​ 154 Total ​ $ 154 ​ $ 13,704 ​ $ 1,045 ​ $ 14,903 ​ On December 31, 2020, our plan’s assets of $17.3 million were invested in five separate funds including a multi-asset fund (29.8%), a diversified growth fund (29.7%), corporate bonds (28.4%), and insurance contracts (6.4%). The asset and growth funds aim to generate an ‘equity-like’ return over an economic cycle with significantly reduced volatility relative to equity markets and have scope to use a diverse range of asset classes, including equities, bonds, cash, and alternatives, e.g., property, infrastructure, high yield bonds, floating rate debt, private, equity, hedge funds and currency. These investments are intended to provide a degree of protection against changes in the value of our plan’s liabilities related to changes in long-term expectations for interest rates and inflation expectations. Expected future payments under defined benefit pension plans, based on foreign exchange rates as of December 31, 2020, are as follows: ​ ​ ​ ​ ​ Expected Future Benefit Payments ​ ​ ​ 2021 $ 2,255 2022 ​ ​ 1,972 2023 ​ ​ 2,184 2024 ​ ​ 2,891 2025 ​ ​ 2,301 2026 - 2030 ​ ​ 49,098 ​

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
STOCK-BASED COMPENSATION.
STOCK-BASED COMPENSATION	NOTE 18. As of December 31, 2020, we had two active stock-based incentive compensation plan: the 2017 Omnibus Incentive Plan and the Employee Stock Purchase Plan ("ESPP"). All new equity compensation grants are issued under these two plans; however, outstanding awards previously issued under inactive plans will continue to vest and remain exercisable in accordance with the terms of the respective plans. Our stock plans are administered by the Board of Directors Compensation Committee. On December 31, 2020, there were 3.0 million shares reserved and 2.3 million shares available for future grant under our stock-based incentive plans. 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 and 2008 Plan provide 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 may be issued as performance-based awards to align stock compensation awards to the attainment of annual or long-term performance goals. As of December 31, 2020, there were 2.1 million shares available for grant under the 2017 Plan. The Company grants restricted stock units and performance stock units. The grant date fair values of restricted stock units and performance stock units are based on the closing market price of our common stock on the grant date. Our restricted stock units vest based on continued service. Our performance stock units vest based on achievement of certain performance goals and certification of performance achievement by the Compensation Committee of the Board of Directors. Stock-based compensation expense, net of forfeitures, is recognized on a straight-line basis over the requisite service period. For performance stock units, compensation expense is updated for the Company’s expected performance level against performance goals at the end of each reporting period, which involves judgment as to achievement of certain performance metrics. ​ Stock-based Compensation Expense 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Stock-based compensation expense ​ $ 12,272 ​ $ 7,327 ​ $ 9,703 ​ Our stock-based compensation expense is based on the value of the portion of share-based payment awards that are ultimately expected to vest, assuming estimated forfeitures at the time of grant. Estimated forfeiture rates for our stock-based compensation expense applicable to stock options and restricted stock units ("RSU’s") were approximately 5%, 10% and 10% for the years ended December 31, 2020, 2019 and 2018, respectively. Restricted Stock Units The fair value of our RSUs is determined based upon the closing fair market value of our common stock on the grant date. Changes in the unvested RSUs were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Grant ​ Shares ​ Value RSUs outstanding at beginning of period 534 ​ $ 56.56 RSUs granted 342 ​ 59.51 RSUs vested (152) ​ 57.14 RSUs forfeited (116) ​ 58.10 RSUs outstanding at end of period 608 ​ $ 58.15 ​ The total intrinsic value of RSUs converted to shares for the years ended December 31, 2020, 2019 and 2018 were $9.2 million, $8.3 million, and $13.6 million, respectively. As of December 31, 2020, there was $7.8 million of total unrecognized compensation cost, net of expected forfeitures related to non-vested RSUs granted, which is expected to be recognized through November 2023, with a weighted-average remaining vesting period of 1.0 years. Stock Options 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 ten years Changes in our outstanding stock options were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Exercise ​ Shares ​ Price Options outstanding at beginning of period 185 ​ $ 21.56 Options exercised (33) ​ 13.43 Options forfeited — ​ — Options expired (5) ​ 15.43 Options outstanding at end of period 147 ​ $ 23.63 ​ The total intrinsic value of options exercised for the years ended December 31, 2020, 2019 and 2018 was $1.9 million, $1.6 million and $4.1 million, respectively. All options outstanding on December 31, 2020 are vested and have aggregate intrinsic value of $10.8 million and weighted-average remaining contractual life of 3.9 years. The following table summarizes information about the stock options outstanding on December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding and Exercisable ​ ​ ​ ​ Weighted-Average ​ Weighted- ​ ​ Number ​ Remaining ​ Average Range of Exercise Prices Outstanding Contractual Life Exercise Price $9.51 to $12.44 5 0.67 years ​ $ 11.18 $18.77 43 3.75 years ​ 18.77 $26.32 99 4.10 years ​ 26.32 $9.51 to $26.32 147 3.89 years ​ $ 23.63 ​ Employee Stock Purchase Plan The ESPP, a stockholder-approved plan, provides for the issuance of rights to purchase up to 1,000,000 shares of common stock. In May 2010, stockholders approved an increase from 500,000 to 1,000,000 shares authorized for sale under our ESPP. Employees below the Vice President level are eligible to participate in the ESPP if employed by us for at least 20 hours per week during at least five months per calendar year. Participating employees may contribute up to the lesser of 15% of their eligible earnings or $5,000 during each plan period. Currently, the plan period is six months. The purchase price of common stock purchased under the ESPP is currently equal to the lower of 1) 85% of the fair market value of our common stock on the commencement date of each plan period or 2) 85% of the fair market value of our common shares on each plan period purchase date. On December 31, 2020, 0.2 million shares remained available for future issuance under the ESPP. Purchase rights granted under the ESPP are valued using the Black-Scholes-Merton model. As of December 31, 2020, there was $0.4 million of total unrecognized compensation cost related to the ESPP that is expected to be recognized over a remaining period of five months. Total compensation expense was $0.9 million for the year ended December 31, 2020 and $0.5 million for the year ended December 31, 2019, and $0.4 million for the year ended December 31, 2018. The fair value of each purchase right granted under the ESPP was estimated on the date of grant using the Black-Scholes-Merton option pricing model with the following assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 Risk-free interest rates 0.10% - 0.18% % 1.62% - 2.31 % 2.10% - 2.56 % Expected dividend yield rates — % — % — % Expected term 0.5 years 0.5 years 0.5 years ​ Expected volatility 70.1 % 41.3 % 38.0 % ​ The risk-free interest rate is based on the six-month U.S. Treasury Bill at the time of the grant. We utilize our historical experience in determining the expected term of our stock options and volatility of our common stock. We have not historically issued dividends.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	NOTE 19. COMMITMENTS AND CONTINGENCIES Disputes and Legal Actions We are involved in disputes and legal actions arising in the normal course of our business. While we currently believe that the amount of any ultimate loss would not be material to our financial position, the outcome of these actions is inherently difficult to predict. In the event of an adverse outcome, the ultimate loss could have a material adverse effect on our financial position or reported results of operations. An unfavorable decision in patent litigation also could require material changes in production processes and products or result in our inability to ship products or components found to have violated third-party patent rights. We accrue loss contingencies in connection with our commitments and contingencies, including litigation, when it is probable that a loss has occurred, and the amount of the loss can be reasonably estimated. The Company is currently not a party to any legal action that the Company believes would reasonably have a material adverse impact on its business, financial condition, results of operations or cash flows. ​

GEOGRAPHIC AND SIGNIFICANT CUST

GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION	12 Months Ended
	Dec. 31, 2020
GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION
GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION	NOTE 20. GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION The following table summarizes sales, and percentages of sales, by customers that individually accounted for 10% or more of our sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 Applied Materials, Inc. ​ ​ $ 248,350 17.5 % ​ $ 164,724 20.9 % ​ $ 258,027 35.9 % Lam Research ​ ​ 141,778 10.0 % ​ 88,251 11.2 % ​ 109,005 15.2 % ​ 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 33,402 14.2 % $ 36,849 14.9 % Nidec Motor Corporation ​ ​ 24,344 ​ 10.4 % ​ 38,071 ​ 15.4 % ​ Our sales to Applied Materials, Inc., Lam Research Corp., and Nidec Corporation include precision power products used in semiconductor processing and solar and flat panel display. No other customer accounted for 10% or more of our sales or accounts receivable balances during these periods. The following table summarizes long-lived assets by geographic area: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 United States ​ $ 253,115 ​ $ 239,511 Asia ​ 283,549 ​ 301,020 Europe ​ 60,847 ​ 59,925 Total ​ $ 597,511 ​ $ 600,456 ​ Long-lived assets include property and equipment, operating lease right-of-use assets goodwill, and other intangible assets.

CREDIT FACILITY

CREDIT FACILITY	12 Months Ended
	Dec. 31, 2020
CREDIT FACILITY
CREDIT FACILITY	NOTE 21. 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 Term Loan Facility and Revolving Facility bear interest, at the option of the Company, at a rate based on a reserve adjusted Eurodollar Rate or a Base Rate, as defined in the Credit Agreement, plus an applicable margin. Additionally, the Revolving Facility is subject to an unused line fee. As of December 31, 2020, the effective interest rate for the Revolving Facility and Term Loan Facility was The fair value of the Company’s outstanding debt approximates the carrying value of $322.0 million as of December 31, 2020. In connection ​ The debt obligation on our Consolidated Balance Sheets consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Debt: ​ ​ ​ ​ ​ ​ Term Loan Facility ​ $ 323,750 ​ $ 341,250 Less: debt issuance costs ​ ​ (1,704) ​ ​ (2,223) Total debt ​ ​ 322,046 ​ ​ 339,027 Less current portion of long-term debt ​ ​ (17,500) ​ ​ (17,500) Total long-term debt ​ $ 304,546 ​ $ 321,527 ​ Contractual maturities of the Company’s debt obligations, excluding amortization of debt issuance costs, as of are as December 31, 2020 follows: ​ ​ ​ ​ ​ Year Ending December 31, Amount 2021 ​ $ 17,500 2022 ​ ​ 17,500 2023 ​ ​ 17,500 2024 ​ ​ 271,250 Total ​ $ 323,750 ​ Interest expense and unused line of credit fees were recorded in Other income (expense), net, in our Consolidated Statements of Operations as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Interest expense ​ $ 5,080 ​ $ 2,994 ​ $ — Amortization of debt issuance costs ​ ​ 519 ​ ​ 186 ​ ​ — Unused line of credit fees and other ​ ​ 153 ​ ​ 236 ​ ​ 228 Total interest expense ​ $ 5,752 ​ $ 3,416 ​ $ 228 ​

OPERATIONS AND SUMMARY OF SIG_2

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES (Policies)	12 Months Ended
	Dec. 31, 2020
OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES
Principles of Consolidation	Principles of Consolidation
Use of Estimates in the Preparation of the Consolidated Financial Statements	Use of Estimates in the Preparation of the Consolidated Financial Statements —
Foreign Currency Translation	Foreign Currency Translation — For certain other subsidiaries, the functional currency is the U.S. Dollar. Foreign currency transactions are recorded based on exchange rates at the time such transactions arise. Subsequent changes in exchange rates for foreign currency denominated monetary assets and liabilities result in foreign currency transaction gains and losses which are reflected as unrealized (based on period end remeasurement) or realized (upon settlement of the transactions) in Other income (expense), net in our Consolidated Statements of Operations.
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 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 — 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 on 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 21. Credit Facility
Cash, Cash Equivalents, and Marketable Securities	Cash, Cash Equivalents, and Marketable Securities Sometimes we invest excess cash in money market funds not insured by the Federal Deposit Insurance Corporation. We believe that the investments in money market funds are on deposit with credit-worthy financial institutions and that the funds are highly liquid. The investments in money market funds are reported at fair value, with interest income recorded in earnings and are included in "Cash and cash equivalents."
Concentrations of Credit Risk	Concentrations of Credit Risk — We have established a reserve for credit losses based upon factors surrounding the credit risk of specific customers, historical trends, and other information.
Accounts Receivable and Reserve for Credit Losses	Accounts Receivable and Reserve for Credit Losses — Our principal customers are original equipment manufacturers ("OEM") 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, we assess credit risks as a single group. We evaluate collection risk and establish 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.
Inventories	Inventories We regularly review inventory quantities on hand and record a provision to write-down excess and obsolete inventory to its estimated net realizable value, if less than cost, based primarily on historical usage and our estimated forecast of product demand. Demand for our products can fluctuate significantly. A significant decrease in demand could result in an increase in the charges for excess inventory quantities on hand. In addition, our industry is subject to technological change, new product development, and product technological obsolescence that could result in an increase in the amount of obsolete inventory quantities on hand. Therefore, any significant unanticipated changes in demand or technological developments could have a significant impact on the value of our inventory and our reported operating results.
Property and Equipment	Property and Equipment 3 Amortization of leasehold improvements is calculated using the straight-line method over the lease term or the estimated useful life of the assets, whichever period is shorter. Leasehold additions and improvements are capitalized, while maintenance and repairs are expensed as incurred. When depreciable assets are retired, or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any related gains or losses are included in Other income (expense), net, in our Consolidated Statements of Operations.
Purchase accounting	Purchase accounting
Intangible Assets, Goodwill and Other Long-Lived Assets	Intangible Assets, Goodwill and Other Long-Lived Assets The estimation of useful lives and expected cash flows requires us to make judgments regarding future periods that are subject to some factors outside of our control. Changes in these estimates can result in revisions to our carrying value of these assets and may result in material charges to our results of operations. The annual impairment test for goodwill can be performed using an assessment of qualitative factors in determining if it is more likely than not that goodwill is impaired. If this assessment indicates that it is more likely than not that goodwill is impaired, the next step of impairment testing compares the fair value of a reporting unit to its carrying value. Goodwill would be impaired if the resulting implied fair value of goodwill was less than the recorded carrying value of the goodwill.
Debt Issuance Costs	Debt Issuance Costs Note 21. Credit Facility
Revenue Recognition	Revenue Recognition We maintain a worldwide support organization in ten countries, including the United States, the Peoples Republic of China ("PRC"), Japan, Korea, Taiwan, Germany, Ireland, Singapore, Israel, and Great Britain. 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. As part of our ongoing service business, we satisfy our service obligations under extended warranties and preventive maintenance contracts. Extended warranties had previously been offered on our discontinued inverter products. Any up-front fees received for extended warranties or maintenance plans are deferred and recognized ratably over the service periods, as defined in the agreements.
Research and Development Expenses	Research and Development Expenses
Warranty Costs	Warranty Costs 12 five Note 4. Disposed and Discontinued Operations Note 15. Warranties
Stock-Based Compensation	Stock-Based Compensation
Income Taxes	Income Taxes We assess the recoverability of our net deferred tax assets and the need for a valuation allowance on a quarterly basis. Our assessment includes several factors including historical results and taxable income projections for each jurisdiction. The ultimate realization of deferred income tax assets is dependent on the generation of taxable income in appropriate jurisdictions during the periods in which those temporary differences are deductible. We consider the scheduled reversal of deferred income tax liabilities, projected future taxable income, and tax planning strategies in determining the amount of the valuation allowance. Based on the level of historical taxable income and projections for future taxable income over the periods in which the deferred income tax assets are deductible, we determine if we will realize the benefits of these deductible differences. Accounting for income taxes requires a two-step approach to recognize and measure uncertain tax positions. In general, we are subject to regular examination of our income tax returns by the Internal Revenue Service and other tax authorities. The first step is to evaluate the tax position for recognition by determining, if based on the technical merits, it is more likely than not that the position will be sustained upon audit, including resolutions of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement. We regularly assess the likelihood of favorable or unfavorable outcomes resulting from these examinations to determine the adequacy of our provision for income taxes. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. On December 22, 2017, the Tax Act was enacted into law and the new legislation contains several key tax provisions that affected us, including a one-time mandatory transition tax on accumulated foreign earnings and a reduction of the corporate income tax rate to 21%, among others. In conjunction with the Tax Act enactment, the SEC issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act Under U.S. GAAP, an accounting policy election can be made to either recognize deferred taxes for temporary basis differences expected to reverse as global intangible low-tax income ("GILTI") in future years, or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. We have elected to account for GILTI in the year the tax is incurred.
Leases	Leases Right-of-use assets and operating lease liabilities are recognized at the present value of the future lease payments on the lease commencement date. The interest rate used to determine the present value of the future lease payments is our incremental borrowing rate, because the interest rate implicit in our leases is not readily determinable. Our incremental borrowing rate is estimated to approximate the interest rate on a collateralized basis with similar terms and payments. Our lease terms include periods under options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Right-of-use assets also include any prepaid lease payments and lease incentives. Operating lease expense is recognized on a straight-line basis over the lease term.
Commitments and Contingencies	Commitments and Contingencies
New Accounting Standards	NEW ACCOUNTING STANDARDS New Accounting Standards Adopted In December 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes" ​ In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820)" In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" New Accounting Standards In August 2018, the FASB issued ASU 2018-14, "Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20)" effective for interim and annual periods 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.

BUSINESS ACQUISITIONS (Tables)

BUSINESS ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Business Acquisition [Line Items]
Summary of intangible assets	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 ​
Versatile Power Inc [Member]
Business Acquisition [Line Items]
Schedule of components of fair value of total consideration transferred	​ ​ ​ ​ ​ Cash paid for acquisition $ 4,594 Holdback ​ ​ 950 Contingent consideration ​ ​ 1,500 Total fair value of consideration transferred ​ ​ 7,044 Less cash acquired ​ ​ (245) Total purchase price ​ $ 6,799
Schedule of fair value of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ Preliminary Current asset and liabilities, net ​ $ 1,015 Property and equipment ​ ​ 35 Operating lease right-of-use assets ​ ​ 453 Intangible assets ​ ​ 4,000 Goodwill ​ ​ 1,749 Total assets acquired ​ ​ 7,252 Operating lease liability ​ ​ 453 Total liabilities assumed ​ ​ 453 Total fair value of net assets acquired ​ $ 6,799
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Schedule of components of fair value of total consideration transferred	The components of the fair value of the total consideration transferred are 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
Schedule of fair value of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ Final Fair 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
Schedule of unaudited pro forma information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2019 ​ As Reported Pro Forma Total sales $ 788,948 $ 1,202,790 Net income attributable to Advanced Energy Industries, Inc. $ 64,941 $ 83,104 Earnings per share: ​ ​ ​ ​ Basic earnings per share ​ $ 1.70 ​ $ 2.17 Diluted earnings per share ​ $ 1.69 ​ $ 2.16

REVENUE (Tables)

REVENUE (Tables)	12 Months Ended
	Dec. 31, 2020
REVENUE
Schedule of disaggregation of revenue	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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 ​ Semiconductor Equipment ​ $ 611,864 ​ $ 403,018 ​ $ 533,770 ​ Industrial and Medical ​ 313,646 ​ 245,992 ​ 185,122 ​ Data Center Computing ​ ​ 322,539 ​ ​ 91,438 ​ ​ — ​ Telecom and Networking ​ ​ 167,777 ​ ​ 48,500 ​ ​ — Total ​ $ 1,415,826 ​ $ 788,948 ​ $ 718,892 ​ ​ The following table presents our sales by geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 North America ​ $ 687,814 48.6 % $ 373,634 47.4 % $ 372,834 51.8 % Asia ​ 606,893 42.9 ​ 295,155 37.4 ​ 250,574 34.9 ​ Europe ​ 117,990 8.3 ​ 119,427 15.1 ​ 94,793 13.2 ​ Other ​ 3,129 0.2 ​ 732 0.1 ​ 691 0.1 ​ Total ​ $ 1,415,826 100.0 % $ 788,948 100.0 % $ 718,892 100.0 % ​ 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Product and service revenue recognized at point in time ​ $ 1,414,982 ​ $ 786,918 ​ $ 715,055 Extended warranty and service contracts recognized over time ​ 844 ​ 2,030 ​ 3,837 Total ​ $ 1,415,826 ​ $ 788,948 ​ $ 718,892

DISPOSED AND DISCONTINUED OPE_2

DISPOSED AND DISCONTINUED OPERATIONS (Tables)	12 Months Ended
	Dec. 31, 2020
DISPOSED AND DISCONTINUED OPERATIONS
Schedule of disposal groups, including discontinued operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Sales ​ $ — ​ $ — Cost of sales ​ — ​ (901) Total operating expense ​ 620 ​ 1,022 Operating income (loss) from discontinued operations ​ (620) ​ (121) Other income (expense) ​ 65 ​ 10,895 Income (loss) from discontinued operations before income taxes ​ (555) ​ 10,774 Provision (benefit) for income taxes ​ (134) ​ 2,294 Income (loss) from discontinued operations, net of income taxes ​ $ (421) ​ $ 8,480

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
Schedule of geographic distribution of pretax income from continuing operations	The geographic distribution of pretax income from continuing operations is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Domestic ​ $ 17,526 ​ $ (20,597) ​ $ 22,325 Foreign ​ 140,621 ​ 87,791 ​ 150,051 ​ ​ $ 158,147 ​ $ 67,194 ​ $ 172,376
Schedule of tax expense and the effective tax rate for income from continuing operations	The provision for income taxes from continuing operations is summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Current: ​ ​ ​ Federal ​ $ 5,475 ​ $ (9,627) ​ $ 1,423 State ​ 1,927 ​ 882 ​ 12 Foreign ​ 16,216 ​ 18,429 ​ 13,772 Total current provision ​ $ 23,618 ​ $ 9,684 ​ $ 15,207 Deferred: ​ ​ ​ Federal ​ $ (312) ​ $ 3,822 ​ $ 4,021 State ​ 1,270 ​ (178) ​ 2,363 Foreign ​ (1,580) ​ (2,629) ​ 3,636 Total deferred provision (benefit) ​ (622) ​ 1,015 ​ 10,020 Total provision for income taxes ​ $ 22,996 ​ $ 10,699 ​ $ 25,227
Schedule of effective income tax rate reconciliation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Income taxes per federal statutory rate ​ $ 33,211 ​ $ 14,111 ​ $ 36,199 State income taxes, net of federal deduction ​ ​ 2,793 ​ ​ 10 ​ ​ 2,372 U.S. tax on foreign operations ​ ​ 9,666 ​ ​ 5,805 ​ ​ 6,943 Foreign derived intangible income deduction ​ ​ (4,070) ​ ​ – ​ ​ (261) Tax effect of foreign operations ​ ​ (20,527) ​ ​ (13,086) ​ ​ (19,162) Uncertain tax position ​ ​ (3,215) ​ ​ (4,487) ​ ​ (3,088) Unremitted earnings ​ ​ (567) ​ ​ 1,624 ​ ​ 2,564 Tax credits ​ ​ (2,292) ​ ​ (2,088) ​ ​ (1,484) Change in valuation allowance ​ ​ (1,175) ​ ​ 7,222 ​ ​ (1,306) Withholding taxes ​ ​ 4,265 ​ ​ 6,500 ​ ​ 1,371 Other permanent items, net ​ ​ 4,907 ​ ​ (4,912) ​ ​ 1,079 Total provision for income taxes ​ $ 22,996 ​ $ 10,699 ​ $ 25,227
Schedule of deferred tax assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Deferred tax assets ​ ​ Stock-based compensation ​ $ 2,130 ​ $ 1,757 Net operating loss and tax credit carryforwards ​ 57,590 ​ 86,879 Interest expense limitation ​ ​ 7,344 ​ ​ 7,620 Pension obligation ​ 14,297 ​ 13,473 Excess and obsolete inventory ​ 3,722 ​ 3,217 Accrued restructuring ​ ​ 2,468 ​ ​ — Deferred revenue ​ 3,048 ​ 3,305 Employee bonuses and commissions ​ 5,388 ​ 2,537 Depreciation and amortization ​ 28,786 ​ 29,015 Operating lease liabilities ​ ​ 20,267 ​ ​ 23,451 Other ​ 8,925 ​ 9,685 Deferred tax assets ​ 153,965 ​ 180,939 Less: Valuation allowance ​ (46,702) ​ (76,206) Net deferred tax assets ​ 107,263 ​ 104,733 Deferred tax liabilities ​ ​ Depreciation and amortization ​ 40,266 ​ 41,549 Unremitted earnings ​ 4,173 ​ 4,740 Operating lease right-of-use assets ​ ​ 18,731 ​ ​ 22,774 Other ​ 3,380 ​ 2,966 Deferred tax liabilities ​ 66,550 ​ 72,029 Net deferred tax assets ​ $ 40,713 ​ $ 32,704
Summary of income tax contingencies	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Balance at beginning of period ​ $ 13,009 ​ $ 13,162 ​ $ 15,990 Additions based on tax positions taken during a prior period ​ 219 ​ 484 ​ 94 Additions based on tax positions taken during a prior period – acquisitions ​ — ​ 4,479 ​ 757 Additions based on tax positions taken during the current period ​ — ​ — ​ — Reductions based on tax positions taken during a prior period ​ — ​ (4,295) ​ (153) Reductions related to a lapse of applicable statute of limitations ​ (3,555) ​ (821) ​ (3,144) Reductions related to a settlement with taxing authorities ​ — ​ — ​ (382) Balance at end of period ​ $ 9,673 ​ $ 13,009 ​ $ 13,162

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
EARNINGS PER SHARE
Reconciliation of weighted-average shares outstanding used in calculation of basic and diluted EPS	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Income from continuing operations ​ $ 135,151 ​ $ 56,495 ​ $ 147,149 Income from continuing operations attributable to noncontrolling interest ​ 55 ​ 34 ​ 86 Income from continuing operations attributable to Advanced Energy Industries, Inc. ​ $ 135,096 ​ $ 56,461 ​ $ 147,063 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted-average common shares outstanding ​ 38,314 ​ 38,281 ​ 39,081 Assumed exercise of dilutive stock options and restricted stock units ​ 228 ​ 214 ​ 271 Diluted weighted-average common shares outstanding ​ 38,542 ​ 38,495 ​ 39,352 Continuing operations: ​ ​ ​ Basic earnings per share ​ $ 3.53 ​ $ 1.47 ​ $ 3.76 Diluted earnings per share ​ $ 3.51 ​ $ 1.47 ​ $ 3.74
Schedule of stock options and restricted units excluded in computation of diluted EPS	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Restricted stock units — — 2
Schedule of repurchase of shares of common stock	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (in thousands, except per share amounts) 2020 2019 2018 Amount paid to repurchase shares ​ $ 11,630 ​ $ — ​ $ 95,125 Number of shares repurchased ​ 244 ​ — ​ 1,696 Average repurchase price per share ​ $ 47.75 ​ $ — ​ $ 56.07

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 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. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 Description ​ Balance Sheet Classification ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Value Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ Marketable securities ​ $ — ​ $ 2,654 ​ $ — ​ $ 2,654 Total assets measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,654 ​ $ — ​ $ 2,654 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration ​ Other current liabilities ​ $ — ​ $ — ​ $ 2,009 ​ $ 2,009 Contingent consideration ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 2,940 ​ ​ 2,940 Interest rate swaps ​ Other long-term liabilities ​ ​ — ​ ​ 2,811 ​ ​ — ​ ​ 2,811 Total liabilities measured at fair value on a recurring basis ​ ​ ​ $ — ​ $ 2,811 ​ $ 4,949 ​ $ 7,760 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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)	12 Months Ended
	Dec. 31, 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Interest rate swap contracts ​ $ 273,219 ​ $ —

ACCOUNTS AND OTHER RECEIVABLE_2

ACCOUNTS AND OTHER RECEIVABLE, NET (Tables)	12 Months Ended
	Dec. 31, 2020
ACCOUNTS AND OTHER RECEIVABLE, NET
Schedule of accounts and other receivable	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Amounts billed, net ​ $ 213,560 ​ $ 227,528 Unbilled receivables ​ ​ 21,618 ​ 19,036 Total receivables, net ​ $ 235,178 ​ $ 246,564
Schedule of expected credit losses	​ ​ ​ ​ ​ Balance as of December 31, 2019 $ 7,745 Additions ​ 368 Deductions - write-offs, net of recoveries ​ (511) Balance as of December 31, 2020 ​ $ 7,602

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2020
INVENTORIES
Schedule of components of inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Parts and raw materials ​ $ 141,337 ​ $ 134,816 Work in process ​ 13,702 ​ 10,269 Finished goods ​ 66,307 ​ 84,934 Total ​ $ 221,346 ​ $ 230,019

PROPERTY AND EQUIPMENT, NET (Ta

PROPERTY AND EQUIPMENT, NET (Tables)	12 Months Ended
	Dec. 31, 2020
PROPERTY AND EQUIPMENT, NET
Schedule of details of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Buildings and land ​ $ 1,776 ​ $ 1,693 Machinery and equipment ​ 115,404 ​ 108,945 Computer and communication equipment ​ 26,623 ​ 29,106 Furniture and fixtures ​ 4,352 ​ 4,119 Vehicles ​ 262 ​ 262 Leasehold improvements ​ 42,984 ​ 33,041 Construction in process ​ 3,693 ​ 9,089 ​ ​ 195,094 ​ 186,255 Less: Accumulated depreciation ​ (80,363) ​ (78,146) Property and equipment, net ​ $ 114,731 ​ $ 108,109
Schedule of depreciation expense recorded in continuing operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Depreciation expense ​ $ 27,641 ​ $ 13,979 ​ $ 7,818

GOODWILL (Tables)

GOODWILL (Tables)	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
Schedule of changes in goodwill	​ ​ ​ ​ ​ Balance as of December 31, 2018 ​ $ 101,900 Measurement period adjustments to purchase price allocation ​ ​ (41,996) Additions from acquisition ​ ​ 143,262 Foreign currency translation ​ ​ (234) Balance as of December 31, 2019 $ 202,932 Measurement period adjustments to purchase price allocation ​ ​ 1,957 Additions from acquisition ​ ​ 1,749 Foreign currency translation ​ ​ 3,345 Balance as of December 31, 2020 ​ $ 209,983

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
Schedule of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Carrying Accumulated Net Carrying December 31, 2020 ​ Amount ​ Amortization ​ Amount Technology ​ $ 85,075 ​ $ (24,999) ​ $ 60,076 Customer relationships ​ 114,171 ​ (26,880) ​ 87,291 Trademarks and other ​ 27,021 ​ (5,449) ​ 21,572 Total ​ $ 226,267 ​ $ (57,328) ​ $ 168,939 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Amortization expense ​ $ 20,129 ​ $ 12,168 ​ $ 5,774
Schedule of estimated amortization expense related to intangible assets	​ ​ ​ ​ ​ Year Ending December 31, ​ ​ 2021 ​ $ 20,565 2022 ​ 20,276 2023 ​ 20,257 2024 ​ 17,334 2025 ​ 12,822 Thereafter ​ 77,685 Total ​ $ 168,939

RESTRUCTURING COSTS (Tables)

RESTRUCTURING COSTS (Tables)	12 Months Ended
	Dec. 31, 2020
RESTRUCTURING COSTS
Schedule of restructuring charges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Cost ​ ​ Years Ended December 31, ​ Through December 31, ​ ​ 2020 2019 2018 2020 Severance and related charges $ 9,632 ​ $ 3,042 ​ $ 4,239 ​ $ 16,913 Facility relocation and closure charges ​ 3,534 ​ 1,996 ​ — ​ 5,530 Total restructuring charges ​ $ 13,166 ​ $ 5,038 ​ $ 4,239 ​ $ 22,443
Schedule of restructuring liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred ​ Cost Paid ​ Effect of ​ ​ ​ ​ ​ Balance at ​ and ​ or ​ Changes in ​ Balance at ​ ​ December 31, ​ Charged to ​ Otherwise ​ Exchange ​ December 31, ​ ​ 2019 ​ Expense ​ Settled ​ Rates ​ 2020 Total restructuring liabilities ​ $ 2,172 ​ $ 13,166 ​ $ (4,714) ​ $ 17 ​ $ 10,641

WARRANTIES (Tables)

WARRANTIES (Tables)	12 Months Ended
	Dec. 31, 2020
WARRANTIES
Schedule of changes in accrued product warranties	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Balances at beginning of period ​ $ 6,413 ​ $ 2,084 ​ $ 2,312 Warranty acquired in business combinations ​ 15 ​ 4,818 ​ 305 Increases to accruals ​ 2,996 ​ 1,752 ​ 1,606 Warranty expenditures ​ (4,688) ​ (2,249) ​ (2,127) Effect of changes in exchange rates ​ 44 ​ 8 ​ (12) Balances at end of period ​ $ 4,780 ​ $ 6,413 ​ $ 2,084

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
LEASES
Components of operating lease cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Operating lease cost ​ $ 22,920 ​ $ 11,052 Short-term and variable lease cost ​ ​ 1,895 ​ ​ 4,726 Total operating lease cost ​ $ 24,815 ​ $ 15,778
Schedule of maturities of operating lease liabilities	​ ​ ​ ​ ​ Year Ending December 31, ​ 2021 ​ $ 21,126 2022 ​ 16,177 2023 ​ 12,979 2024 ​ 11,593 2025 ​ ​ 10,133 Thereafter ​ ​ 74,635 Total lease payments ​ ​ 146,643 Less: Interest ​ ​ (34,058) Present value of lease liabilities ​ $ 112,585
Schedule of other information related to leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 ​ Weighted average remaining lease term (in years) ​ ​ 10.65 ​ ​ 7.50 ​ Weighted average discount rate ​ ​ 4.63 % ​ 4.05 % Cash paid for operating lease liabilities ​ $ 21,877 ​ $ 12,101 ​ Right-of-use assets obtained in exchange for operating lease liabilities (1) ​ $ 33,741 ​ $ 84,551 ​ (1) Included in 2019 are the right-of-use assets of $60.1 million obtained in connection with the acquisition of Artesyn in September 2019. Subsequent measurement period adjustments that occurred in the year ended December 31, 2020 reduced this amount to $54.4 million. See Note 2. Business Acquisitions for more details.

EMPLOYEE RETIREMENT PLANS AND_2

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2020
EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS
Changes in projected benefit obligations and plan assets	The Company’s projected benefit obligation and plan assets for defined benefit pension plans and the related assumptions used to determine the related liabilities are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 Projected benefit obligation, beginning of year ​ $ 83,262 ​ $ 33,178 Acquisition ​ — ​ 48,350 Service cost ​ 1,068 ​ 272 Interest cost ​ 1,716 ​ 1,211 Actuarial (gain) loss ​ 7,591 ​ (193) Benefits paid ​ (1,199) ​ (1,779) Translation adjustment ​ 5,302 ​ 2,223 Projected benefit obligation, end of year ​ ​ 97,740 ​ ​ 83,262 ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets, beginning of year ​ ​ 14,903 ​ ​ 13,433 Acquisitions ​ — ​ 102 Actual return on plan assets ​ 682 ​ 380 Contributions ​ 1,827 ​ 644 Benefits paid ​ (993) ​ (1,176) Actuarial gain ​ 180 ​ 1,064 Translation adjustment ​ 694 ​ 456 Fair value of plan assets, end of year ​ ​ 17,293 ​ ​ 14,903 Funded status of plan ​ $ (80,447) ​ $ (68,359)
Schedule of net periodic pension benefit costs	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Service cost ​ $ 1,068 ​ $ 272 ​ $ 841 Interest cost ​ ​ 1,716 ​ ​ 1,211 ​ ​ 802 Expected return on plan assets ​ (683) ​ (615) ​ (665) Amortization of actuarial gains and losses ​ 459 ​ 411 ​ 478 Net periodic pension cost ​ $ 2,560 ​ $ 1,279 ​ $ 1,456
Schedule of assumptions used in determination of net period pension cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Discount rate 1.8 % 2.7 % 2.8 % Expected long-term return on plan assets 3.7 % 4.6 % 4.8 %
Schedule of fair value qualified pension plan assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ Level 1 Level 2 Level 3 Total Multi-Asset Fund ​ $ — ​ $ 5,149 ​ $ — ​ $ 5,149 Diversified Growth Fund ​ — ​ 5,134 ​ — ​ 5,134 Corporate Bonds ​ — ​ 4,906 ​ — ​ 4,906 Insurance Contracts ​ ​ — ​ — ​ 1,109 ​ 1,109 Cash ​ 995 ​ — ​ — ​ 995 Total ​ $ 995 ​ $ 15,189 ​ $ 1,109 ​ $ 17,293 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ Level 1 Level 2 Level 3 Total Multi-Asset Fund ​ $ — ​ $ 4,825 ​ $ — ​ $ 4,825 Diversified Growth Fund ​ — ​ 4,855 ​ — ​ 4,855 Index-Linked Gilts ​ — ​ 1,934 ​ — ​ 1,934 Corporate Bonds ​ — ​ 2,090 ​ — ​ 2,090 Insurance Contracts ​ ​ — ​ ​ — ​ ​ 1,045 ​ ​ 1,045 Cash ​ 154 ​ — ​ — ​ 154 Total ​ $ 154 ​ $ 13,704 ​ $ 1,045 ​ $ 14,903
Schedule of expected future benefit payments under defined benefit pension plans	Expected future payments under defined benefit pension plans, based on foreign exchange rates as of December 31, 2020, are as follows: ​ ​ ​ ​ ​ Expected Future Benefit Payments ​ ​ ​ 2021 $ 2,255 2022 ​ ​ 1,972 2023 ​ ​ 2,184 2024 ​ ​ 2,891 2025 ​ ​ 2,301 2026 - 2030 ​ ​ 49,098

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of stock-based compensation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Stock-based compensation expense ​ $ 12,272 ​ $ 7,327 ​ $ 9,703
Disclosure of compensation related costs	​ ​ ​ ​ ​ ​ ​ ​ ​ 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Grant ​ Shares ​ Value RSUs outstanding at beginning of period 534 ​ $ 56.56 RSUs granted 342 ​ 59.51 RSUs vested (152) ​ 57.14 RSUs forfeited (116) ​ 58.10 RSUs outstanding at end of period 608 ​ $ 58.15
Schedule of shares authorized under stock option plans, by exercise price range	The following table summarizes information about the stock options outstanding on December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding and Exercisable ​ ​ ​ ​ Weighted-Average ​ Weighted- ​ ​ Number ​ Remaining ​ Average Range of Exercise Prices Outstanding Contractual Life Exercise Price $9.51 to $12.44 5 0.67 years ​ $ 11.18 $18.77 43 3.75 years ​ 18.77 $26.32 99 4.10 years ​ 26.32 $9.51 to $26.32 147 3.89 years ​ $ 23.63
Employee Stock [Member]
Schedule of valuation assumptions	The fair value of each purchase right granted under the ESPP was estimated on the date of grant using the Black-Scholes-Merton option pricing model with the following assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 Risk-free interest rates 0.10% - 0.18% % 1.62% - 2.31 % 2.10% - 2.56 % Expected dividend yield rates — % — % — % Expected term 0.5 years 0.5 years 0.5 years ​ Expected volatility 70.1 % 41.3 % 38.0 %
Time Based [Member]
Schedule of stock options roll forward	Changes in our outstanding stock options were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ 2020 ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Exercise ​ Shares ​ Price Options outstanding at beginning of period 185 ​ $ 21.56 Options exercised (33) ​ 13.43 Options forfeited — ​ — Options expired (5) ​ 15.43 Options outstanding at end of period 147 ​ $ 23.63
Schedule of restricted stock and restricted stock units activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding and Exercisable ​ ​ ​ ​ Weighted-Average ​ Weighted- ​ ​ Number ​ Remaining ​ Average Range of Exercise Prices Outstanding Contractual Life Exercise Price $9.51 to $12.44 5 0.67 years ​ $ 11.18 $18.77 43 3.75 years ​ 18.77 $26.32 99 4.10 years ​ 26.32 $9.51 to $26.32 147 3.89 years ​ $ 23.63

GEOGRAPHIC AND SIGNIFICANT CU_2

GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2020
GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION
Schedules of concentration of risk, by risk factor	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ ​ 2020 2019 2018 Applied Materials, Inc. ​ ​ $ 248,350 17.5 % ​ $ 164,724 20.9 % ​ $ 258,027 35.9 % Lam Research ​ ​ 141,778 10.0 % ​ 88,251 11.2 % ​ 109,005 15.2 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2020 ​ ​ 2019 ​ Applied Materials, Inc. ​ $ 33,402 14.2 % $ 36,849 14.9 % Nidec Motor Corporation ​ ​ 24,344 ​ 10.4 % ​ 38,071 ​ 15.4 %
Schedule of long-lived assets by geographic area	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 United States ​ $ 253,115 ​ $ 239,511 Asia ​ 283,549 ​ 301,020 Europe ​ 60,847 ​ 59,925 Total ​ $ 597,511 ​ $ 600,456

CREDIT FACILITY (Tables)

CREDIT FACILITY (Tables)	12 Months Ended
	Dec. 31, 2020
CREDIT FACILITY
Schedule of debt obligation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Debt: ​ ​ ​ ​ ​ ​ Term Loan Facility ​ $ 323,750 ​ $ 341,250 Less: debt issuance costs ​ ​ (1,704) ​ ​ (2,223) Total debt ​ ​ 322,046 ​ ​ 339,027 Less current portion of long-term debt ​ ​ (17,500) ​ ​ (17,500) Total long-term debt ​ $ 304,546 ​ $ 321,527
Schedule of contractual maturities of debt obligations	​ ​ ​ ​ ​ Year Ending December 31, Amount 2021 ​ $ 17,500 2022 ​ ​ 17,500 2023 ​ ​ 17,500 2024 ​ ​ 271,250 Total ​ $ 323,750
Schedule of interest expense and unused line of credit fees	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2020 2019 2018 Interest expense ​ $ 5,080 ​ $ 2,994 ​ $ — Amortization of debt issuance costs ​ ​ 519 ​ ​ 186 ​ ​ — Unused line of credit fees and other ​ ​ 153 ​ ​ 236 ​ ​ 228 Total interest expense ​ $ 5,752 ​ $ 3,416 ​ $ 228

OPERATIONS AND SUMMARY OF SIG_3

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES (Details)	12 Months Ended
	Dec. 31, 2020item
OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES
Number of operating vertical markets	4

OPERATIONS AND SUMMARY OF SIG_4

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Building [Member] | Minimum
Property, Plant and Equipment, Useful Life	20 years
Building [Member] | Maximum
Property, Plant and Equipment, Useful Life	40 years
Machinery, equipment, furniture and fixtures and vehicles [Member]
Property, Plant and Equipment, Useful Life	3 years
Machinery, equipment, furniture and fixtures and vehicles [Member] | Minimum
Property, Plant and Equipment, Useful Life	3 years
Machinery, equipment, furniture and fixtures and vehicles [Member] | Maximum
Property, Plant and Equipment, Useful Life	15 years
Computer and Communication Equipment [Member]
Property, Plant and Equipment, Useful Life	3 years

OPERATIONS AND SUMMARY OF SIG_5

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES - Revenue Recognition and Warrant Costs (Details)	12 Months Ended
	Dec. 31, 2020country
Worldwide support organization maintained in number of countries	10
Precision Power Products [Member] | Minimum
Warranty period	12 months
Precision Power Products [Member] | Maximum
Warranty period	24 months
Inverter Products [Member] | Minimum
Warranty period	5 years
Inverter Products [Member] | Maximum
Warranty period	10 years
Building [Member] | Inverter Products [Member] | Maximum
Additional warranty period	20 years

OPERATIONS AND SUMMARY OF SIG_6

OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES - Income Taxes (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%

BUSINESS ACQUISITIONS - Conside

BUSINESS ACQUISITIONS - Consideration Transferred (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020
Business Acquisition [Line Items]
Total purchase price		$ 6,799
Versatile Power, Inc. [Member]
Business Acquisition [Line Items]
Cash paid for acquisition		4,594
Holdback		950
Contingent consideration		1,500
Total fair value of consideration transferred		7,044
Less cash acquired		(245)
Total purchase price		$ 6,799
Artesyn's Embedded Power Business [Member]
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

BUSINESS ACQUISITIONS - Assets

BUSINESS ACQUISITIONS - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2019	Sep. 10, 2019
Business Acquisition [Line Items]
Current asset and liabilities	$ 1,015
Property and equipment	35
Operating lease right-of-use assets	453
Goodwill	1,749
Intangible assets	4,000
Total assets acquired	7,252
Operating lease liability	453
Total liabilities assumed	453
Total fair value of net assets acquired	6,799
Versatile Power, Inc. [Member]
Business Acquisition [Line Items]
Total fair value of net assets acquired	6,799
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Intangible assets			$ 124,000
Total fair value of net assets acquired		$ 370,236
Artesyn's Embedded Power Business [Member] | 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	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

BUSINESS ACQUISITIONS - Acquisi

BUSINESS ACQUISITIONS - Acquisitions (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Purchase price	$ 6,799
Revolving Facility [Member]
Business Acquisition [Line Items]
Line of credit facility, borrowing capacity		$ 500,000
Versatile Power, Inc. [Member]
Business Acquisition [Line Items]
Purchase price	$ 6,799
Acquired percentage	100.00%
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Purchase price		$ 370,236
Acquired percentage		100.00%

BUSINESS ACQUISITIONS - Schedul

BUSINESS ACQUISITIONS - Schedule of Intangible Assets Acquired, Amortization Method, and Estimated Useful Lives (Details) - USD ($) $ in Thousands	1 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Sep. 10, 2019
Business Acquisition [Line Items]
Amortizable intangible assets:		$ 4,000
Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Amortizable intangible assets:			$ 124,000
Technology Equipment [Member] | Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Amortizable intangible assets:			28,000
Useful Life	5 years
Customer relationships [Member] | Artesyn's Embedded Power Business [Member]
Business Acquisition [Line Items]
Amortizable intangible assets:			75,000
Useful Life	15 years
Tradename | Artesyn's Embedded Power Business [Member]
Business Acquisition [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	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition, Pro Forma Information [Abstract]
Sales, net	$ 1,415,826	$ 788,948	$ 718,892
Total sales, Pro Forma		1,202,790
Net income attributable to Advanced Energy Industries, Inc, As Reported	$ 134,675	64,941	$ 147,025
Net income attributable to Advanced Energy Industries, Inc., Pro Forma		$ 83,104
Earnings Per Share, Pro Forma [Abstract]
Basic earnings per share, As Reported	$ 3.52	$ 1.70	$ 3.76
Basic earnings per share, Pro Forma		2.17
Diluted earnings per share	$ 3.50	1.69	$ 3.74
Diluted earnings per share, Pro Forma		$ 2.16
Artesyn's Embedded Power Business [Member]
Business Acquisition, Pro Forma Information [Abstract]
Sales, net		$ 220,300
Net income attributable to Advanced Energy Industries, Inc, As Reported		$ 7,100

REVENUE - Nature of goods and s

REVENUE - Nature of goods and services (Details) $ in Millions	1 Months Ended
	May 31, 2019USD ($)	Dec. 31, 2020USD ($)country	Dec. 31, 2019USD ($)
REVENUE
Worldwide support organization maintained in number of countries | country		10
Deferred revenue transferred to buyer during sale	$ 22
Deferred Service Revenue		$ 8.7	$ 9.2

REVENUE - Revenue by product li

REVENUE - Revenue by product line (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,415,826	$ 788,948	$ 718,892
Sales to external customers	100.00%	100.00%	100.00%
North America [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 687,814	$ 373,634	$ 372,834
Sales to external customers	48.60%	47.40%	51.80%
Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 606,893	$ 295,155	$ 250,574
Sales to external customers	42.90%	37.40%	34.90%
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 117,990	$ 119,427	$ 94,793
Sales to external customers	8.30%	15.10%	13.20%
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 3,129	$ 732	$ 691
Sales to external customers	0.20%	0.10%	0.10%
Semiconductor Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 611,864	$ 403,018	$ 533,770
Industrial and Medical [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	313,646	245,992	$ 185,122
Data Center Computing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	322,539	91,438
Telecom and Networking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 167,777	$ 48,500

REVENUE - Net sales by extended

REVENUE - Net sales by extended warranty and service contracts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,415,826	$ 788,948	$ 718,892
Product and service revenue recognized at point in time
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,414,982	786,918	715,055
Extended warranty and service contracts recognized over time
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 844	$ 2,030	$ 3,837

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	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
DISPOSED AND DISCONTINUED OPERATIONS
Cost of sales		$ (901)
Total operating expense	$ 620	1,022
Operating income (loss) from discontinued operations	(620)	(121)
Other income (expense)	65	10,895
Income (loss) from discontinued operations before income taxes	(555)	10,774
Provision (benefit) for income taxes	(134)	2,294
Income (loss) from discontinued operations, net of income taxes	$ (421)	$ 8,480	$ (38)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%

INCOME TAXES - Earnings Before

INCOME TAXES - Earnings Before Income Taxes by Geographical Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
Domestic	$ 17,526	$ (20,597)	$ 22,325
Foreign	140,621	87,791	150,051
Income from continuing operations, before income taxes	$ 158,147	$ 67,194	$ 172,376

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal	$ 5,475	$ (9,627)	$ 1,423
State	1,927	882	12
Foreign	16,216	18,429	13,772
Total current provision	23,618	9,684	15,207
Deferred
Federal	(312)	3,822	4,021
State	1,270	(178)	2,363
Foreign	(1,580)	(2,629)	3,636
Total deferred provision (benefit)	(622)	1,015	10,020
Total provision for income taxes	$ 22,996	$ 10,699	$ 25,227

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
Income taxes per federal statutory rate	$ 33,211	$ 14,111	$ 36,199
State income taxes, net of federal deduction	2,793	10	2,372
U.S. tax on foreign operations	9,666	5,805	6,943
Foreign derived intangible income deduction	(4,070)		(261)
Tax effect of foreign operations	(20,527)	(13,086)	(19,162)
Uncertain tax position	(3,215)	(4,487)	(3,088)
Unremitted earnings	(567)	1,624	2,564
Tax credits	(2,292)	(2,088)	(1,484)
Change in valuation allowance	(1,175)	7,222	(1,306)
Withholding taxes	4,265	6,500	1,371
Other permanent items, net	4,907	(4,912)	1,079
Total provision for income taxes	$ 22,996	$ 10,699	$ 25,227

INCOME TAXES - Schedule of Net

INCOME TAXES - Schedule of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
INCOME TAXES
Stock-based compensation	$ 2,130	$ 1,757
Net operating loss and tax credit carryforwards	57,590	86,879
Interest expense limitation	7,344	7,620
Pension obligation	14,297	13,473
Excess and obsolete inventory	3,722	3,217
Accrued restructuring	2,468
Deferred revenue	3,048	3,305
Employee bonuses and commissions	5,388	2,537
Depreciation and Amortization	28,786	29,015
Operating lease liabilities	20,267	23,451
Other	8,925	9,685
Deferred tax assets	153,965	180,939
Less: Valuation allowance	(46,702)	(76,206)
Net deferred tax assets	107,263	104,733
Depreciation and amortization	40,266	41,549
Unremitted earnings	4,173	4,740
Operating lease right-of-use assets	18,731	22,774
Other	3,380	2,966
Deferred tax liabilities	66,550	72,029
Net deferred tax assets	40,713	32,704
Deferred income tax assets	50,801	42,656
Deferred income tax liabilities	$ 10,088	$ 9,952

INCOME TAXES - Valuation Allowa

INCOME TAXES - Valuation Allowances (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 46,702	$ 76,206
Capital loss carryforwards	200
Interest expense limitation carryforwards	30,500
Federal net operating loss carry forwards, have no expiration period	8,000
Income Tax Holiday, Aggregate Dollar Amount	$ 13,000	$ 4,000
Income Tax Holiday, Income Tax Benefits Per Share	$ 0.34	$ 0.12
Decrease in valuation allowance	$ 29,500
Undistributed earnings of foreign subsidiaries	58,900
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Valuation Allowance	4,200
Operating Loss Carryforwards	70,300	$ 70,300
Tax Credit Carryforward, Amount	1,300
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Valuation Allowance	42,500
Operating Loss Carryforwards	129,600
State Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	117,700
Tax Credit Carryforward, Amount	$ 1,700

INCOME TAXES - Reconciliation_2

INCOME TAXES - Reconciliation of Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Balance at beginning of period	$ 13,009	$ 13,162	$ 15,990
Additions based on tax positions taken during a prior period	219	484	94
Reductions based on tax positions taken during a prior period		(4,295)	(153)
Reductions related to a lapse of applicable statute of limitations	(3,555)	(821)	(3,144)
Reductions related to a settlement with taxing authorities			(382)
Balance at end of period	$ 9,673	13,009	13,162
Acquisitions [Member]
Income Tax Contingency [Line Items]
Additions based on tax positions taken during a prior period		$ 4,479	$ 757

INCOME TAXES - Unrecognized Tax

INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INCOME TAXES
Unrecognized Tax Benefits	$ 9,673	$ 13,009	$ 13,162	$ 15,990
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3,200	$ 3,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 3,500

EARNINGS PER SHARE - Reconcilia

EARNINGS PER SHARE - Reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
EARNINGS PER SHARE
Income from continuing operations	$ 135,151	$ 56,495	$ 147,149
Income from continuing operations attributable to noncontrolling interest	55	34	86
Income from continuing operations attributable to Advanced Energy Industries, Inc.	$ 135,096	$ 56,461	$ 147,063
Basic weighted-average common shares outstanding	38,314	38,281	39,081
Assumed exercise of dilutive stock options and restricted stock units	228	214	271
Diluted weighted-average common shares outstanding	38,542	38,495	39,352
Continuing Operations:
Basic earnings per share (in dollars per share)	$ 3.53	$ 1.47	$ 3.76
Diluted earnings per share (in dollars per share)	$ 3.51	$ 1.47	$ 3.74

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 in Thousands	12 Months Ended
	Dec. 31, 2018shares
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	2

EARNINGS PER SHARE - Stock Buyb

EARNINGS PER SHARE - Stock Buyback (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 18, 2019	May 03, 2018	Sep. 16, 2015
EARNINGS PER SHARE
Authorized amount	$ 38,400				$ 150,000
Authorized program period repurchase	30 months
Authorized amount increase			$ 25,100	$ 50,000
Amount paid to repurchase shares	$ 11,630	$ 95,125
Number of shares repurchased	244	1,696
Average repurchase price per share	$ 47.75	$ 56.07

FAIR VALUE MEASUREMENTS - Asset

FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 2,654	$ 2,614
Total liabilities	7,760	1,377
Contingent Consideration [Member] | Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	2,009
Contingent Consideration [Member] | Other Long-Term Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	2,940	1,377
Interest Rate Swap [Member] | Other Long-Term Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	2,811
Certificates of Deposit [Member] | Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,654	2,614
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,654	2,614
Total liabilities	2,811
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member] | Other Long-Term Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	2,811
Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member] | Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,654	2,614
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	4,949	1,377
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member] | Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	2,009
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member] | Other Long-Term Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	$ 2,940	$ 1,377

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
FAIR VALUE MEASUREMENTS
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)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Loan value, percentage	85.00%
Annual interest (as a percent)	1.271%
Average fixed rate	0.521%
Cash Flow Hedge | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Basis points at current leverage ratios	75

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS - Qualified Hedging Instruments (Details) - Interest Rate Swap [Member] $ in Thousands	Dec. 31, 2020USD ($)
Derivative [Line Items]
Derivative, notional amount	$ 273,219
Changes in fair value on the interest rate swaps	$ 2,100

ACCOUNTS AND OTHER RECEIVABLE_3

ACCOUNTS AND OTHER RECEIVABLE, NET (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	$ 235,178	$ 246,564
Amounts billed, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	213,560	227,528
Unbilled receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	$ 21,618	$ 19,036

ACCOUNTS AND OTHER RECEIVABLE_4

ACCOUNTS AND OTHER RECEIVABLE, NET - Expected Credit losses - (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
ACCOUNTS AND OTHER RECEIVABLE, NET
Balance as of beginning of period	$ 7,745
Additions	368
Write-offs	(511)
Balance as of end of period	$ 7,602

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
INVENTORIES
Parts and raw materials	$ 141,337	$ 134,816
Work in process	13,702	10,269
Finished goods	66,307	84,934
Total	$ 221,346	$ 230,019

PROPERTY AND EQUIPMENT, NET - D

PROPERTY AND EQUIPMENT, NET - Details of property and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 195,094	$ 186,255
Less: Accumulated depreciation	(80,363)	(78,146)
Property and equipment, net	114,731	108,109
Buildings and Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,776	1,693
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	115,404	108,945
Computer and Communication Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,623	29,106
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,352	4,119
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	262	262
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	42,984	33,041
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,693	$ 9,089

PROPERTY AND EQUIPMENT, NET -_2

PROPERTY AND EQUIPMENT, NET - Depreciation expense recorded in continuing operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
PROPERTY AND EQUIPMENT, NET
Depreciation expense	$ 27,641	$ 13,979	$ 7,818

GOODWILL - Schedule of the chan

GOODWILL - Schedule of the changes in goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
GOODWILL AND INTANGIBLE ASSETS
Balance as of Beginning of Period	$ 202,932	$ 101,900
Measurement period adjustments to preliminary purchase price allocation	1,957	(41,996)
Additions from acquisition	1,749	143,262
Foreign currency translation	3,345	(234)
Balance as of End of Period	$ 209,983	$ 202,932

INTANGIBLE ASSETS - Schedule of

INTANGIBLE ASSETS - Schedule of intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 226,267	$ 219,251
Finite-Lived Intangible Assets, Accumulated Amortization	(57,328)	(35,240)
Finite-lived intangible assets, net	$ 168,939	184,011
Amortization of weighted average remaining useful life	10 years 6 months
Technology Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 85,075	83,368
Finite-Lived Intangible Assets, Accumulated Amortization	(24,999)	(14,250)
Finite-lived intangible assets, net	60,076	69,118
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	114,171	108,995
Finite-Lived Intangible Assets, Accumulated Amortization	(26,880)	(18,197)
Finite-lived intangible assets, net	87,291	90,798
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	27,021	26,888
Finite-Lived Intangible Assets, Accumulated Amortization	(5,449)	(2,793)
Finite-lived intangible assets, net	$ 21,572	$ 24,095

INTANGIBLE ASSETS - Schedule _2

INTANGIBLE ASSETS - Schedule of amortization expense relating to intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
GOODWILL AND INTANGIBLE ASSETS
Amortization expense	$ 20,129	$ 12,168	$ 5,774

INTANGIBLE ASSETS - Schedule _3

INTANGIBLE ASSETS - Schedule of Finite-Lived Intangible Assets, Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
GOODWILL AND INTANGIBLE ASSETS
2021	$ 20,565
2022	20,276
2023	20,257
2024	17,334
2025	12,822
Thereafter	77,685
Finite-lived intangible assets, net	$ 168,939	$ 184,011

RESTRUCTURING COSTS (Details)

RESTRUCTURING COSTS (Details) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 13,166	$ 5,038	$ 4,239	$ 22,443
Severance and related charges
Restructuring Cost and Reserve [Line Items]
Restructuring expense	9,632	3,042	$ 4,239	16,913
Facility relocation and closure charges
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 3,534	$ 1,996		$ 5,530

RESTRUCTURING COSTS - Schedule

RESTRUCTURING COSTS - Schedule of Restructuring liabilities (Details) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Restructuring Reserve [Roll Forward]
Beginning balance	$ 2,172
Cost incurred and charged to expense	13,166	$ 5,038	$ 4,239	$ 22,443
Cost paid or otherwise settled	(4,714)
Effect of change in exchange rates	17
Ending balance	$ 10,641	$ 2,172		$ 10,641

WARRANTIES - Narrative (Details

WARRANTIES - Narrative (Details)	12 Months Ended
	Dec. 31, 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 accrued

WARRANTIES - Changes in accrued product warranties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement in Standard Product Warranty Accrual [Roll Forward]
Balances at beginning of period	$ 6,413	$ 2,084	$ 2,312
Warranty acquired in business combinations	15	4,818	305
Increases to accruals	2,996	1,752	1,606
Warranty expenditures	(4,688)	(2,249)	(2,127)
Effect of changes in exchange rates	44	8	(12)
Balances at end of period	$ 4,780	$ 6,413	$ 2,084

LEASES - Components of operatin

LEASES - Components of operating lease cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
LEASES
Operating lease cost	$ 22,920	$ 11,052
Short-term and variable lease cost	1,895	4,726
Total operating lease costs	$ 24,815	$ 15,778

LEASES - Operating lease maturi

LEASES - Operating lease maturity schedule (Details) $ in Thousands	Dec. 31, 2020USD ($)
LEASES
2021	$ 21,126
2022	16,177
2023	12,979
2024	11,593
2025	10,133
Thereafter	74,635
Total lease payments	146,643
Less: Interest	(34,058)
Present value of lease liabilities	$ 112,585

LEASES - Payments (Details)

LEASES - Payments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)agreement
LEASES
Number of lease agreements | agreement	1
Total payments | $	$ 3.5
Term of contract	5 years

LEASES - Other lease cost infor

LEASES - Other lease cost information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term (in years)	10 years 7 months 24 days	7 years 6 months
Weighted average discount rate	4.63%	4.05%
Cash paid for operating lease liabilities	$ 21,877	$ 12,101
Right-of-use assets obtained in exchange for operating lease liabilities	33,741	84,551
Operating lease right-of-use assets	453
Artesyn's Embedded Power Business [Member]
Lessee, Lease, Description [Line Items]
Right-of-use assets obtained in exchange for operating lease liabilities		$ 60,100
Preliminary Fair Value [Member] | Artesyn's Embedded Power Business [Member]
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 54,439

EMPLOYEE RETIREMENT PLANS AND_3

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Defined Contribution Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS
Defined Contribution Plan, vesting period	4 years
Matching contributions	50.00%	50.00%	50.00%
Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%	6.00%	6.00%
Defined Contribution Plan, Cost	$ 2.6	$ 1.6	$ 1.4

EMPLOYEE RETIREMENT PLANS AND_4

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Projected Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in projected benefit obligation
Projected benefit obligation, beginning of year	$ 83,262	$ 33,178
Acquisition		48,350
Service cost	1,068	272	$ 841
Interest cost	1,716	1,211	802
Actuarial (gain) loss	7,591	(193)
Benefits paid	(1,199)	(1,779)
Translation adjustment	5,302	2,223
Projected benefit obligation, end of year	97,740	83,262	33,178
Changes in fair value of plan assets
Fair value of plan assets, beginning of year	14,903	13,433
Acquisitions		102
Actual return on plan assets	682	380
Contributions	1,827	644
Benefits paid	(993)	(1,176)
Actuarial gain	180	1,064
Translation adjustment	694	456
Fair value of plan assets, end of year	17,293	14,903	$ 13,433
Funded status of plan	$ (80,447)	$ (68,359)

EMPLOYEE RETIREMENT PLANS AND_5

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Net periodic pension benefit cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net periodic pension benefit cost
Service cost	$ 1,068	$ 272	$ 841
Interest cost	1,716	1,211	802
Expected return on plan assets	(683)	(615)	(665)
Amortization of actuarial gain and losses	459	411	478
Net periodic pension cost	$ 2,560	$ 1,279	$ 1,456

EMPLOYEE RETIREMENT PLANS AND_6

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Net Periodic Pension Cost Assumptions (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assumptions used in the determination of the net periodic pension cost:
Discount rate	1.80%	2.70%	2.80%
Expected long-term return on plan assets	3.70%	4.60%	4.80%

EMPLOYEE RETIREMENT PLANS AND_7

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Fair Value of Plan Assets by Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 17,293	$ 14,903	$ 13,433
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	15,189	13,704
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	1,109	1,045
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	995	154
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 5,149	4,825
Investment percentage within Plan Asset category	29.80%
Multi-asset Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 5,149	4,825
Diversified Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 5,134	4,855
Investment percentage within Plan Asset category	29.70%
Diversified Growth Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 5,134	4,855
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets		1,934
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets		1,934
Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 4,906	2,090
Investment percentage within Plan Asset category	28.40%
Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 4,906	2,090
Insurance Contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 1,109	1,045
Investment percentage within Plan Asset category	6.40%
Insurance Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 1,109	1,045
Defined Benefit Plan, Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	995	154
Defined Benefit Plan, Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of Plan Assets	$ 995	$ 154

EMPLOYEE RETIREMENT PLANS AND_8

EMPLOYEE RETIREMENT PLANS AND POSTRETIREMENT BENEFITS - Expected Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Expected Future Benefit Payments
2021	$ 2,255
2022	1,972
2023	2,184
2024	2,891
2025	2,301
2026 - 2030	$ 49,098

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2020USD ($)plan$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	May 01, 2010shares	Apr. 30, 2010shares
Stock-based incentive compensation plans | plan	2
Shares reserved | shares	3,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares	2,300,000
Estimated Forfeiture rates for Share Based Compensation	5.00%	10.00%	10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 1,900,000	$ 1,600,000	$ 4,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 10,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	1 year
Awards term	10 years
Stock-based compensation expense	$ 12,272,000	$ 7,327,000	$ 9,703,000
2017 OMNIBUS Incentive Plan [Member] [Domain]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares	2,100,000
RSUs [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 7,800,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months	6 months	6 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	70.10%	41.30%	38.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Minimum
Vesting period	3 years
Minimum | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.10%	1.62%	2.10%
Maximum
Vesting period	4 years
Maximum | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.18%	2.31%	2.56%
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 9,200,000	$ 8,300,000	$ 13,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares	$ 59.51
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | shares	1,000,000			1,000,000	500,000
Share-based Compensation Arrangement By Share-based Payment Award, Employee Contribution, Amount	$ 5,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	85.00%
Employee Stock [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares	200,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 400,000
Employee Service Share-based Compensation recognized remaining period	5 months
Stock-based compensation expense	$ 900,000	$ 500,000	$ 400,000
Employee Stock [Member] | Maximum
Share-based Compensation Arrangement By Share-based Payment Award, Employee Contribution, Percent	15.00%

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of stock-based compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
STOCK-BASED COMPENSATION
Stock-based compensation expense	$ 12,272	$ 7,327	$ 9,703

STOCK-BASED COMPENSATION - Fair

STOCK-BASED COMPENSATION - Fair Value Assumptions by Grant Year (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Estimated Forfeiture rates for Share Based Compensation	5.00%	10.00%	10.00%
Stock-based compensation expense	$ 12,272	$ 7,327	$ 9,703
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months	6 months	6 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	70.10%	41.30%	38.00%
Minimum | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.10%	1.62%	2.10%
Maximum | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.18%	2.31%	2.56%

STOCK-BASED COMPENSATION - Sc_2

STOCK-BASED COMPENSATION - Schedule of Weighted Average Fair Value and Intrinsic Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
STOCK-BASED COMPENSATION.
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 1.9	$ 1.6	$ 4.1

STOCK-BASED COMPENSATION - Chan

STOCK-BASED COMPENSATION - Changes in Outstanding Stock Options (Details) - Time Based [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at beginning of period | shares	185
Exercised | shares	(33)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period | shares	0
Expired | shares	(5)
Outstanding at ending of period | shares	147
Weighted-Average Exercise Price Per Share, Beginning Balance | $ / shares	$ 21.56
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	13.43
Weighted-Average Exercise Price Per Share, Forfeited | $ / shares	0
Weighted-Average Exercise Price Per Share, Expired | $ / shares	15.43
Weighted-Average Exercise Price Per Share, End Balance | $ / shares	$ 23.63

STOCK-BASED COMPENSATION - Sc_3

STOCK-BASED COMPENSATION - Schedule of Stock Options by Exercise Price (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
9.51 - 12.44 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options | shares	5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	8 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 11.18
18.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 18.77
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options | shares	43
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 9 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.77
26.32 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 26.32
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options | shares	99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	4 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 26.32
9.51 - 26.32 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options | shares	147
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 10 months 20 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 23.63
Minimum | 9.51 - 12.44 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	9.51
Minimum | 9.51 - 26.32 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	9.51
Maximum | 9.51 - 12.44 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	12.44
Maximum | 9.51 - 26.32 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 26.32

STOCK-BASED COMPENSATION - Ch_2

STOCK-BASED COMPENSATION - Changes in RSU (Details) - RSUs [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	608	534
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 58.15	$ 56.56
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	342
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(152)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 57.14
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(116)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 58.10
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 59.51

STOCK-BASED COMPENSATION - Sc_4

STOCK-BASED COMPENSATION - Schedule of Weighted Average Fair Value and Intrinsic Value for RSUs (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 1.9	$ 1.6	$ 4.1
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 58.15	$ 56.56
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 9.2	$ 8.3	$ 13.6

GEOGRAPHIC AND SIGNIFICANT CU_3

GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Major Customer [Line Items]
Sales, net	$ 1,415,826	$ 788,948	$ 718,892
Product [Member]
Revenue, Major Customer [Line Items]
Sales, net	1,296,867	678,061	610,326
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Sales, net	$ 248,350	$ 164,724	$ 258,027
Significant concentration risk, 10% or more of total balance	17.50%	20.90%	35.90%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Lam Research [Member]
Revenue, Major Customer [Line Items]
Sales, net	$ 141,778	$ 88,251	$ 109,005
Significant concentration risk, 10% or more of total balance	10.00%	11.20%	15.20%
Accounts Receivable [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Significant concentration risk, 10% or more of total balance	14.20%	14.90%
Accounts receivable	$ 33,402	$ 36,849
Accounts Receivable [Member] | Nidec Motor Corporation [Member]
Revenue, Major Customer [Line Items]
Significant concentration risk, 10% or more of total balance	10.40%	15.40%
Accounts receivable	$ 24,344	$ 38,071

GEOGRAPHIC AND SIGNIFICANT CU_4

GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION - Schedule of Long-lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 597,511	$ 600,456
United States [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	253,115	239,511
Asia [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	283,549	301,020
Europe [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 60,847	$ 59,925

CREDIT FACILITY (Details)

CREDIT FACILITY (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2019
Line of Credit Facility [Line Items]
Long-term debt	$ 322,046	$ 339,027
Loan value, percentage	85.00%
Average fixed rate	0.521%
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
Revolving Facility [Member] | Bank of America N.A. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	$ 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
Revolving Credit Facility and Term Loan Facility
Line of Credit Facility [Line Items]
Effective rate percentage	1.26%
Interest Rate Swap [Member]
Line of Credit Facility [Line Items]
Derivative, notional amount	$ 273,219

CREDIT FACILITY - Debt obligati

CREDIT FACILITY - Debt obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt:
Term Loan Facility	$ 323,750	$ 341,250
Less: debt issuance costs	(1,704)	(2,223)
Total debt	322,046	339,027
Less current portion of long-term debt	(17,500)	(17,500)
Total long-term debt	$ 304,546	$ 321,527

CREDIT FACILITY - Contractual m

CREDIT FACILITY - Contractual maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CREDIT FACILITY
2021	$ 17,500
2022	17,500
2023	17,500
2024	271,250
Total	$ 323,750	$ 341,250

CREDIT FACILITY - Interest expe

CREDIT FACILITY - Interest expense and unused line of credit fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CREDIT FACILITY
Interest expense	$ 5,080	$ 2,994
Amortization of debt issuance costs	519	186
Unused line of credit fees and other	153	236	$ 228
Total interest expense	$ 5,752	$ 3,416	$ 228