Power Integrations (POWI) 10-Q 29 Jul 21 2021 Q2 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - $ / shares	6 Months Ended
	Jun. 30, 2021	Jul. 26, 2021
Document and Entity Information
Title of 12(b) Security	Common Stock
Entity Address, Address Line One	5245 Hellyer Avenue
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
Entity Incorporation, State or Country Code	DE
Document Type	10-Q
Document Quarterly Report	true
Current Fiscal Year End Date	--12-31
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	000-23441
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Listing, Par Value Per Share	$ 0.001
Entity Registrant Name	POWER INTEGRATIONS, INC.
Trading Symbol	POWI
Entity Central Index Key	0000833640
Entity Filer Category	Large Accelerated Filer
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		60,290,603
Entity Tax Identification Number	94-3065014
Entity Address, Postal Zip Code	95138
Security Exchange Name	NASDAQ
City Area Code	408
Local Phone Number	414-9200
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 297,481	$ 258,874
Short-term marketable securities	217,777	190,318
Accounts receivable, net	41,352	35,910
Inventories	89,643	102,878
Prepaid expenses and other current assets	21,292	13,252
Total current assets	667,545	601,232
PROPERTY AND EQUIPMENT, net	167,079	166,188
INTANGIBLE ASSETS, net	10,601	12,506
GOODWILL	91,849	91,849
DEFERRED TAX ASSETS	2,072	3,339
OTHER ASSETS	28,703	28,225
Total assets	967,849	903,339
CURRENT LIABILITIES:
Accounts payable	41,898	34,712
Accrued payroll and related expenses	16,652	14,806
Taxes payable	989	902
Other accrued liabilities	8,727	12,106
Total current liabilities	68,266	62,526
LONG-TERM INCOME TAXES PAYABLE	14,340	15,588
OTHER LIABILITIES	14,899	14,814
Total liabilities	97,505	92,928
COMMITMENTS AND CONTINGENCIES (Notes 11, 12 and 13)
STOCKHOLDERS' EQUITY:
Common stock	28	28
Additional paid-in capital	185,878	190,920
Accumulated other comprehensive loss	(3,155)	(2,163)
Retained earnings	687,593	621,626
Total stockholders' equity	870,344	810,411
Total liabilities and stockholders' equity	$ 967,849	$ 903,339

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
NET REVENUES	$ 180,110	$ 106,832	$ 353,847	$ 216,496
COST OF REVENUES	88,797	53,296	178,123	106,480
GROSS PROFIT	91,313	53,536	175,724	110,016
OPERATING EXPENSES:
Research and development	21,741	19,770	41,768	38,922
Sales and marketing	15,290	13,037	29,413	26,510
General and administrative	9,306	7,804	19,381	16,565
Total operating expenses	46,337	40,611	90,562	81,997
INCOME FROM OPERATIONS	44,976	12,925	85,162	28,019
OTHER INCOME	173	1,480	770	3,257
INCOME BEFORE INCOME TAXES	45,149	14,405	85,932	31,276
PROVISION FOR INCOME TAXES	3,268	1,213	4,253	2,198
NET INCOME	$ 41,881	$ 13,192	$ 81,679	$ 29,078
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.69	$ 0.22	$ 1.35	$ 0.49
Diluted (in dollars per share)	$ 0.68	$ 0.22	$ 1.33	$ 0.48
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)	60,544	59,712	60,366	59,458
Diluted (in shares)	61,466	60,624	61,481	60,464

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (Parenthetical)	Aug. 18, 2020
Income Statement [Abstract]
Stock split ratio	2

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 41,881	$ 13,192	$ 81,679	$ 29,078
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in each of the three and six months ended June 30, 2021 and 2020	(40)	(30)	(58)	(313)
Unrealized gain (loss) on marketable securities, net of $0 tax in each of the three and six months ended June 30, 2021 and 2020	(331)	2,566	(911)	1,614
Amortization of defined benefit pension items, net of tax of $6 and $141 in the three and six months ended June 30, 2021 respectively, and $24 and $55 in the three and six months ended June 30, 2020, respectively	52	58	(23)	109
Total other comprehensive income (loss)	(319)	2,594	(992)	1,410
TOTAL COMPREHENSIVE INCOME	$ 41,562	$ 15,786	$ 80,687	$ 30,488

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0	$ 0
Unrealized gain (loss) on marketable securities, tax	0	0	0	0
Amortization of defined benefit pension items, tax	$ 6	$ 24	$ 141	$ 55

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total
Beginning balance at Dec. 31, 2019	$ 28	$ 152,117	$ (3,130)	$ 575,531
Common stock issued under employee stock plans	0	6,298
Repurchase of common stock	0	(2,636)
Stock-based compensation		12,691
Other comprehensive income (loss)			1,410		$ 1,410
Net income				29,078	29,078
Payment of dividends to stockholders				(11,915)
Ending balance at Jun. 30, 2020	28	168,470	(1,720)	592,694	759,472
Beginning balance at Mar. 31, 2020	28	162,343	(4,314)	585,773
Common stock issued under employee stock plans	0	769
Repurchase of common stock	0	(623)
Stock-based compensation		5,981
Other comprehensive income (loss)			2,594		2,594
Net income				13,192	13,192
Payment of dividends to stockholders				(6,271)
Ending balance at Jun. 30, 2020	28	168,470	(1,720)	592,694	759,472
Beginning balance at Dec. 31, 2020	28	190,920	(2,163)	621,626	810,411
Common stock issued under employee stock plans	1	3,651
Repurchase of common stock	(1)	(26,373)			(26,400)
Stock-based compensation		17,680
Other comprehensive income (loss)			(992)		(992)
Net income				81,679	81,679
Payment of dividends to stockholders				(15,712)
Ending balance at Jun. 30, 2021	28	185,878	(3,155)	687,593	870,344
Beginning balance at Mar. 31, 2021	29	203,051	(2,836)	653,579
Common stock issued under employee stock plans	0
Repurchase of common stock	(1)	(26,373)
Stock-based compensation		9,200
Other comprehensive income (loss)			(319)		(319)
Net income				41,881	41,881
Payment of dividends to stockholders				(7,867)
Ending balance at Jun. 30, 2021	$ 28	$ 185,878	$ (3,155)	$ 687,593	$ 870,344

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 81,679	$ 29,078
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,274	11,069
Amortization of intangibles	1,905	2,207
Loss on disposal of property and equipment	38	292
Stock-based compensation expense	17,680	12,691
Amortization of premium on marketable securities	300	321
Deferred income taxes	1,182	1,279
Increase (decrease) in accounts receivable allowance for credit losses	91	(154)
Change in operating assets and liabilities:
Accounts receivable	(5,533)	11,556
Inventories	13,235	(13,583)
Prepaid expenses and other assets	(4,501)	4,092
Accounts payable	8,053	5,861
Taxes payable and accrued liabilities	(4,433)	(1,665)
Net cash provided by operating activities	124,970	63,044
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(19,294)	(21,622)
Proceeds from sale of property and equipment	35	331
Purchases of marketable securities	(188,753)	(19,827)
Proceeds from sales and maturities of marketable securities	160,083	58,962
Net cash provided by (used in) investing activities	(47,929)	17,844
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	3,652	6,298
Repurchase of common stock	(26,374)	(2,636)
Payments of dividends to stockholders	(15,712)	(11,915)
Net cash used in financing activities	(38,434)	(8,253)
NET INCREASE IN CASH AND CASH EQUIVALENTS	38,607	72,635
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	258,874	178,690
CASH AND CASH EQUIVALENTS AT END OF PERIOD	297,481	251,325
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	5,070	13,932
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid (received) for income taxes, net	$ 10,084	$ (2,155)

BASIS OF PRESENTATION

BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	1. BASIS OF PRESENTATION: The condensed consolidated financial statements include the accounts of Power Integrations, Inc., a Delaware corporation (the “Company”), and its wholly owned subsidiaries. Significant intercompany accounts and transactions have been eliminated in consolidation. While the financial information furnished is unaudited, the condensed consolidated financial statements included in this report reflect all adjustments (consisting only of normal recurring adjustments) that the Company considers necessary for the fair presentation of the results of operations for the interim periods covered and the financial condition of the Company at the date of the interim balance sheet in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The results for interim periods are not necessarily indicative of the results for the entire year. The condensed consolidated financial statements should be read in conjunction with the Company’s consolidated financial statements and the notes thereto for the year ended December 31, 2020, included in its Form 10-K filed on February 5, 2021, with the Securities and Exchange Commission. The share and per share information for all periods presented in this Form 10-Q reflects the effect of the August 2020 two-for-one stock split. Refer to Note 8, Stockholders’ Equity Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations. ​

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Jun. 30, 2021
Accounting Policies And Recent Accounting Pronouncements [Abstract]
SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	2. SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS: Significant Accounting Policies and Estimates No material changes have been made to the Company’s significant accounting policies disclosed in Note 2, Significant Accounting Policies and Recent Accounting Pronouncements Recent Accounting Pronouncements The Company has considered all recent accounting pronouncements issued, but not yet effective, and does not expect any to have a material effect on the Company’s condensed consolidated financial statements. ​

COMPONENTS OF THE COMPANY'S CON

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS	3. COMPONENTS OF THE COMPANY’S CONDENSED CONSOLIDATED BALANCE SHEETS: Accounts Receivable ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, (In thousands) ​ 2021 ​ 2020 Accounts receivable trade ​ $ 78,759 ​ $ 66,703 Allowance for ship and debit ​ (33,738) ​ (26,435) Allowance for stock rotation and rebate ​ (3,151) ​ (3,931) Allowance for credit losses ​ ​ (518) ​ ​ (427) Total ​ $ 41,352 ​ $ 35,910 ​ ​ The Company maintains an allowance for estimated credit losses resulting from the inability of customers to make required payments. This allowance is established using estimates formulated by the Company’s management based upon factors such as the composition of the accounts receivable aging, historical losses, changes in payments patterns, customer creditworthiness, and current economic trends. Receivables determined to be uncollectible are written off and deducted from the allowance. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) ​ 2021 2020 2021 2020 Beginning balance ​ $ (425) ​ $ (609) ​ $ (427) ​ $ (763) Provision for credit loss expense ​ (360) ​ — ​ (577) ​ — Receivables written off ​ — ​ — ​ — ​ 154 Recoveries collected ​ 267 ​ — ​ 486 ​ — Ending balance ​ $ (518) ​ $ (609) ​ $ (518) ​ $ (609) ​ Inventories ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, (In thousands) ​ 2021 ​ 2020 Raw materials ​ $ 23,285 ​ $ 32,131 Work-in-process ​ 35,488 ​ 39,469 Finished goods ​ 30,870 ​ 31,278 Total ​ $ 89,643 ​ $ 102,878 ​ Intangible Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ (In thousands) ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Domain name ​ $ 1,261 ​ $ — ​ $ 1,261 ​ $ 1,261 ​ $ — ​ $ 1,261 Developed technology ​ 37,960 ​ (30,500) ​ 7,460 ​ 37,960 ​ (29,126) ​ 8,834 Customer relationships ​ 16,700 ​ (16,095) ​ 605 ​ 16,700 ​ (15,687) ​ 1,013 Technology licenses ​ 1,926 ​ (651) ​ 1,275 ​ 1,926 ​ (528) ​ 1,398 Total intangible assets ​ $ 57,847 ​ $ (47,246) ​ $ 10,601 ​ $ 57,847 ​ $ (45,341) ​ $ 12,506 ​ ​ The estimated future amortization expense related to finite-lived intangible assets at June 30, 2021, is as follows: ​ ​ ​ ​ ​ Estimated ​ ​ Amortization Fiscal Year ​ (In thousands) 2021 (remaining six months) ​ $ 1,589 2022 ​ 2,415 2023 ​ 2,173 2024 ​ 1,279 2025 ​ 832 Thereafter ​ 1,052 Total ​ $ 9,340 ​ Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss for the three and six months ended June 30, 2021 and 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ Defined Benefit ​ Foreign Currency ​ ​ ​ ​ Marketable Securities ​ Pension Items ​ Items ​ Total ​ Three Months Ended ​ Three Months Ended ​ Three Months Ended ​ Three Months Ended ​ June 30, ​ June 30, ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 2021 2020 2021 2020 Beginning balance $ 310 ​ $ (369) ​ $ (1,716) ​ $ (2,433) ​ $ (1,430) ​ $ (1,512) ​ $ (2,836) ​ $ (4,314) Other comprehensive income (loss) before reclassifications (331) ​ 2,566 ​ — ​ — ​ (40) ​ (30) ​ (371) ​ 2,536 Amounts reclassified from accumulated other comprehensive loss — ​ — ​ 52 (1) 58 (1) — ​ — ​ 52 ​ 58 Net-current period other comprehensive income (loss) (331) ​ 2,566 ​ 52 ​ 58 ​ (40) ​ (30) ​ (319) ​ 2,594 Ending balance $ (21) ​ $ 2,197 ​ $ (1,664) ​ $ (2,375) ​ $ (1,470) ​ $ (1,542) ​ $ (3,155) ​ $ (1,720) ​ (1) This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the three months ended June 30, 2021 and 2020. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ Defined Benefit Pension ​ Foreign Currency ​ ​ ​ ​ Marketable Securities ​ Items ​ Items ​ Total ​ Six Months Ended ​ Six Months Ended ​ Six Months Ended ​ Six Months Ended ​ June 30, ​ June 30, ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 ​ 2020 2021 2020 2021 2020 Beginning balance $ 890 ​ $ 583 ​ $ (1,641) ​ $ (2,484) ​ $ (1,412) ​ $ (1,229) ​ $ (2,163) ​ $ (3,130) Other comprehensive income (loss) before reclassifications (911) ​ 1,614 ​ — ​ — ​ (58) ​ (313) ​ (969) ​ 1,301 Amounts reclassified from accumulated other comprehensive loss — ​ — ​ (23) (1) 109 (1) — ​ — ​ (23) ​ 109 Net-current period other comprehensive income (loss) (911) ​ 1,614 ​ (23) ​ 109 ​ (58) ​ (313) ​ (992) ​ 1,410 Ending balance $ (21) ​ $ 2,197 ​ $ (1,664) ​ $ (2,375) ​ $ (1,470) ​ $ (1,542) ​ $ (3,155) ​ $ (1,720) (1) This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the six months ended June 30, 2021 and 2020.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	4. FAIR VALUE MEASUREMENTS: The FASB established a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: (Level 1) observable inputs such as quoted prices for identical assets in active markets; (Level 2) inputs other than the quoted prices in active markets that are observable either directly or indirectly; and (Level 3) unobservable inputs in which there is little or no market data, which requires the Company to develop its own assumptions. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. The Company’s cash equivalents and short-term marketable securities are classified within Level 1 or Level 2 of the fair-value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The fair-value hierarchy of the Company’s cash equivalents and marketable securities at June 30, 2021, and December 31, 2020, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ June 30, 2021 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 341,013 ​ $ — ​ $ 341,013 Corporate securities ​ ​ 107,780 ​ ​ — ​ ​ 107,780 Money market funds ​ 1,865 ​ 1,865 ​ — Total ​ $ 450,658 ​ $ 1,865 ​ $ 448,793 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2020 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Corporate securities ​ $ 146,658 ​ $ — ​ $ 146,658 Commercial paper ​ 253,855 ​ — ​ 253,855 Money market funds ​ 1,634 ​ 1,634 ​ — Total ​ $ 402,147 ​ $ 1,634 ​ $ 400,513 ​ The Company did not transfer any investments between Level 1 and Level 2 of the fair-value hierarchy in the six months ended June 30, 2021, and the twelve months ended December 31, 2020.

MARKETABLE SECURITIES

MARKETABLE SECURITIES	6 Months Ended
	Jun. 30, 2021
Marketable Securities [Abstract]
MARKETABLE SECURITIES	5. MARKETABLE SECURITIES: Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at June 30, 2021, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 77,195 ​ $ — ​ $ — ​ $ 77,195 Corporate securities ​ ​ 23,948 ​ ​ 46 ​ ​ (6) ​ ​ 23,988 Total ​ 101,143 ​ 46 ​ (6) ​ 101,183 Investments due in 4-12 months: ​ ​ ​ ​ Commercial paper ​ ​ 34,306 ​ ​ — ​ ​ — ​ ​ 34,306 Corporate securities ​ 20,675 ​ 47 ​ (5) ​ 20,717 Total ​ 54,981 ​ 47 ​ (5) ​ 55,023 Investments due in 12 months or greater: ​ ​ ​ ​ Corporate securities ​ 61,674 ​ — ​ (103) ​ 61,571 Total ​ ​ 61,674 ​ — ​ ​ (103) ​ 61,571 Total marketable securities ​ $ 217,798 ​ $ 93 ​ $ (114) ​ $ 217,777 ​ Accrued interest receivable was $0.6 million at June 30, 2021 and was recorded within prepaid expenses and other current assets on the condensed consolidated balance sheet. Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 43,660 ​ $ — ​ $ — ​ $ 43,660 Corporate securities ​ ​ 19,846 ​ ​ 44 ​ ​ — ​ ​ 19,890 Total ​ 63,506 ​ 44 ​ — ​ 63,550 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 125,922 ​ 846 ​ — ​ 126,768 Total ​ 125,922 ​ 846 ​ — ​ 126,768 Total marketable securities ​ $ 189,428 ​ $ 890 ​ $ — ​ $ 190,318 ​ Accrued interest receivable was $0.8 million at December 31, 2020 and was recorded within prepaid expenses and other current assets on the condensed consolidated balance sheet. The following table summarizes marketable securities classified as available-for-sale (excluding cash equivalents) in a continuous unrealized loss position for which an allowance for credit losses was not recorded at June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less Than 12 Months ​ 12 Months or Longer ​ Total ​ Estimated Gross Estimated Gross Estimated Gross ​ ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized (In thousands) ​ Value ​ Losses ​ Value ​ Losses ​ Value ​ Losses Corporate securities ​ $ 69,194 ​ $ (114) ​ $ — ​ $ — ​ $ 69,194 ​ $ (114) Total marketable securities ​ $ 69,194 ​ $ (114) ​ $ — ​ $ — ​ $ 69,194 ​ $ (114) ​ In the three and six months ended June 30, 2021 and 2020, no unrealized losses on marketable securities were recognized in income. The Company does not intend to sell and it is unlikely that it will be required to sell the securities prior to their anticipated recovery. The issuers are high quality (investment grade) and the decline in fair value is largely due to changes in interest rates and other market conditions. Additionally, the issuers continue to make timely interest payments on the marketable securities with the fair value expected to recover as they reach maturity.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	6. STOCK-BASED COMPENSATION: The following table summarizes the stock-based compensation expense recognized in accordance with ASC 718-10 for the three and six months ended June 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 Cost of revenues ​ $ 640 ​ $ 252 ​ $ 1,271 ​ $ 648 Research and development ​ 3,159 ​ 2,351 ​ 5,550 ​ 4,460 Sales and marketing ​ 1,725 ​ 1,258 ​ 3,339 ​ 2,650 General and administrative ​ 3,676 ​ 2,120 ​ 7,520 ​ 4,933 Total stock-based compensation expense ​ $ 9,200 ​ $ 5,981 ​ $ 17,680 ​ $ 12,691 ​ ​ Stock-based compensation expense in the three months ended June 30, 2021, was approximately $9.2 million, comprising approximately $4.7 million related to restricted stock unit (RSU) awards, $4.0 million related to performance-based (PSU) awards and long-term performance-based (PRSU) awards and $0.5 million related to the Company’s employee stock purchase plan. Stock-based compensation expense in the six months ended June 30, 2021, was approximately $17.7 million, comprising approximately $10.0 million related to RSUs, $6.7 million related to PSUs and PRSUs and $1.0 million related to the Company’s employee stock purchase plan. Stock-based compensation expense in the three months ended June 30, 2020, was approximately $6.0 million, comprising approximately $4.5 million related to RSUs, $1.1 million related to PSUs and PRSUs and $0.4 million related to the Company’s employee stock purchase plan. Stock-based compensation expense in the six months ended June 30, 2020, was approximately $12.7 million, comprising approximately $9.5 million related to RSUs, $2.4 million related to PSUs and PRSUs and $0.8 million related to the Company’s employee stock purchase plan. Stock Options A summary of stock options outstanding as of June 30, 2021, and activity during the six months then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ ​ ​ Average ​ Contractual ​ Aggregate ​ ​ Shares ​ Exercise ​ Term ​ Intrinsic Value ​ (In thousands) Price (In years) (In thousands) Outstanding at January 1, 2021 92 ​ $ 20.63 ​ ​ ​ Granted — ​ — ​ Exercised (33) ​ $ 19.15 ​ Forfeited or expired — ​ — ​ Outstanding at June 30, 2021 59 ​ $ 21.44 0.85 ​ $ 3,602 Vested and exercisable at June 30, 2021 59 ​ ​ ​ 0.85 ​ $ 3,602 ​ PSU Awards Under the performance-based awards program, the Company grants awards in the performance year in an amount equal to twice the target number of shares to be issued if the maximum performance metrics are met. The number of shares that are released at the end of the performance year can range from zero to 200% of the target number depending on the Company’s performance. The performance metrics of this program are annual targets consisting of a combination of net revenue, non-GAAP operating income and strategic goals. As the net revenue, non-GAAP operating income and strategic goals are considered performance conditions, expense associated with these awards, net of estimated forfeitures, is recognized over the service period based on an assessment of the achievement of the performance targets. The fair value of these PSUs is determined using the fair value of the Company’s common stock on the date of the grant, reduced by the discounted present value of dividends expected to be declared before the awards vest. If the performance conditions are not achieved, no compensation cost is recognized and any previously recognized compensation is reversed. In January 2021, it was determined that approximately 150,000 shares subject to the PSUs granted in 2020 vested in aggregate; the shares were released to the Company’s employees and executives in the first quarter of 2021. A summary of PSUs outstanding as of June 30, 2021, and activity during the six months ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 150 ​ $ 46.27 ​ ​ ​ Granted 100 ​ $ 84.45 ​ Vested (150) ​ $ 46.27 ​ Forfeited — ​ ​ — ​ Outstanding at June 30, 2021 100 ​ $ 84.45 0.50 ​ $ 8,228 Outstanding and expected to vest at June 30, 2021 100 ​ ​ ​ 0.50 ​ $ 8,228 ​ PRSU Awards The Company’s PRSU program provides for the issuance of PRSUs which will vest based on the Company’s performance measured against the PRSU program’s established performance targets. PRSUs are granted in an amount equal to twice the target number of shares to be issued if the maximum performance metrics are met. The actual number of shares the recipient receives is determined at the end of a three-year performance period based on results achieved versus the Company’s performance goals, and may range from zero to 200% of the target number. The performance goals for PRSUs granted in fiscal 2019 were based on the Company’s annual revenue growth, while the PRSUs granted in 2020 and 2021 were based on the Company’s compound annual growth rate (“CAGR”) of revenue as measured against the revenue CAGR of the analog semiconductor industry, in each case over the respective three-year performance period. Expense associated with these awards, net of estimated forfeitures, is recorded throughout the year based on an assessment of the expected achievement of the performance targets. If the performance conditions are not achieved, no compensation cost is recognized and any previously recognized compensation is reversed. In January 2021 it was determined that approximately 6,000 shares subject to the PRSUs granted in 2018 vested in aggregate; the shares were released to the Company’s executives in the first quarter of 2021. A summary of PRSUs outstanding as of June 30, 2021, and activity during the six months ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 301 ​ $ 41.90 ​ ​ ​ Granted 97 ​ $ 83.00 ​ Vested (6) ​ $ 29.95 ​ Forfeited (15) ​ $ 40.05 ​ Outstanding at June 30, 2021 377 ​ $ 52.75 1.40 ​ $ 30,956 Outstanding and expected to vest at June 30, 2021 377 ​ ​ ​ 1.40 ​ $ 30,956 ​ RSU Awards A summary of RSUs outstanding as of June 30, 2021, and activity during the six months then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 1,518 ​ $ 35.51 ​ ​ ​ Granted 227 ​ $ 82.94 ​ Vested (524) ​ $ 34.53 ​ Forfeited (71) ​ $ 36.41 ​ Outstanding at June 30, 2021 1,150 ​ $ 45.29 1.70 ​ $ 94,342 Outstanding and expected to vest at June 30, 2021 1,064 ​ ​ ​ 1.65 ​ $ 87,279 ​

SIGNIFICANT CUSTOMERS AND GEOGR

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES	6 Months Ended
	Jun. 30, 2021
Risks and Uncertainties [Abstract]
SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES	7. SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES: Segment Reporting The Company is organized and operates as one reportable segment, the design, development, manufacture and marketing of integrated circuits and related components for use primarily in the high-voltage power-conversion market. The Company’s chief operating decision maker, the Chief Executive Officer, reviews financial information presented on a consolidated basis for purposes of making operating decisions and assessing financial performance. Customer Concentration The Company’s top ten customers accounted for approximately 80% of net revenues in both the three and six months ended June 30, 2021, and approximately 59% and 56%, respectively, of net revenues in the corresponding periods of 2020. A significant portion of these revenues are attributable to sales of the Company’s products to distributors of electronic components. These distributors sell the Company’s products to a broad, diverse range of end users, including original equipment manufacturers, or OEMs, and merchant power supply manufacturers. Sales to distributors were $136.4 million and $270.7 million in the three and six months ended June 30, 2021, respectively, and $87.3 million and $170.8 million, respectively, for the corresponding periods of 2020. Direct sales to OEMs and power-supply manufacturers accounted for the remainder. The following customers represented 10% or more of the Company’s net revenues for the respective periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, ​ June 30, Customer ​ 2021 ​ 2020 ​ 2021 ​ 2020 Avnet 29 % ​ 13 % 30 % ​ 12 % Honestar Technologies Co., Ltd. ​ 19 % ​ * ​ ​ 19 % ​ * ​ ​ * Total customer revenue was less than 10% of net revenues. No other customers accounted for 10% or more of the Company’s net revenues in the periods presented. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash investments and trade receivables. The Company does not have any off-balance-sheet credit exposure related to its customers. As of June 30, 2021, and December 31, 2020, 84% and 90%, respectively, of accounts receivable were concentrated with the Company’s top ten customers. The following customers represented 10% or more of accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, Customer 2021 ​ 2020 Avnet ​ 46 % ​ 50 % Powertech Distribution Ltd. * ​ ​ 10 % * Total customer accounts receivable was less than 10% of accounts receivable. No other customers accounted for 10% or more of the Company’s accounts receivable in the periods presented. Geographic Net Revenues The Company markets its products globally through its sales personnel and a worldwide network of independent sales representatives and distributors. Geographic net revenues, based on “bill to” customer locations, for the three and six months ended June 30, 2021 and 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 United States of America ​ $ 3,819 ​ $ 2,935 ​ $ 7,919 ​ $ 5,648 Hong Kong/China ​ 122,123 ​ 65,680 ​ 240,853 ​ 126,093 Taiwan ​ 6,361 ​ 7,199 ​ 12,803 ​ 13,678 Korea ​ 13,705 ​ 7,284 ​ 26,194 ​ 17,641 Western Europe (excluding Germany) ​ 8,720 ​ 7,995 ​ 15,850 ​ 18,030 Japan ​ 5,152 ​ 4,398 ​ 9,799 ​ 8,303 Germany ​ 7,656 ​ 5,847 ​ 14,662 ​ 11,414 Other ​ 12,574 ​ 5,494 ​ 25,767 ​ 15,689 Total net revenues ​ $ 180,110 ​ $ 106,832 ​ $ 353,847 ​ $ 216,496 ​

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
STOCKHOLDERS' EQUITY	8. STOCKHOLDERS’ EQUITY: Common Stock Shares Outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 Beginning balance ​ ​ 60,363 ​ ​ 59,382 ​ ​ 59,910 ​ ​ 58,862 Common stock issued under employee stock plans ​ 316 ​ 386 ​ 769 ​ 954 Repurchased ​ (335) ​ (16) ​ (335) ​ (64) Ending balance ​ ​ 60,344 ​ ​ 59,752 ​ ​ 60,344 ​ ​ 59,752 ​ In July 2020, the Company’s board of directors approved a two-for-one stock split in the form of a stock dividend, payable on August 18, 2020, to stockholders of record as of the close of business on August 14, 2020. The Company’s stockholders received one additional share of common stock for each share of common stock held on August 14, 2020. The share and per share information for all periods presented in this Form 10-Q reflects the effect of the stock split. Common Stock Repurchases As of December 31, 2020, the Company had approximately $41.3 million remaining under its stock-repurchase program. In April 2021, the Company’s board of directors authorized the use of an additional $50.0 million for the repurchase of the Company’s common stock, with repurchases to be executed according to pre-defined price/volume guidelines. In . Cash Dividends In October 2019, the Company’s board of directors declared four quarterly cash dividends of $0.095 per share to be paid to stockholders of record at the end of each quarter in 2020. In April 2020, the Company’s board of directors raised the cash dividends with the declaration of three cash dividends of $0.105 per share share In January 2021, For the three and six months ended June 30, 2021 and 2020, cash dividends declared and paid were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands, except per share amounts) 2021 2020 2021 2020 Dividends declared and paid ​ $ 7,867 ​ $ 6,271 ​ $ 15,712 ​ $ 11,915 Dividends declared per common share ​ $ 0.13 ​ $ 0.105 ​ $ 0.26 ​ $ 0.20 ​

EARNINGS PER SHARE

EARNINGS PER SHARE	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
EARNINGS PER SHARE	9. EARNINGS PER SHARE: Basic earnings per share are calculated by dividing net income by the weighted-average shares of common stock outstanding during the period. Diluted earnings per share are calculated by dividing net income by the weighted-average shares of common stock and dilutive common equivalent shares outstanding during the period. Dilutive common equivalent shares included in this calculation consist of dilutive shares issuable upon the assumed exercise of outstanding common stock options, the assumed vesting of outstanding restricted stock units, the assumed issuance of awards under the stock purchase plan and contingently issuable performance-based awards, as computed using the treasury stock method. A summary of the earnings per share calculation is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands, except per share amounts) 2021 2020 2021 2020 Basic earnings per share: ​ ​ ​ ​ Net income ​ $ 41,881 ​ $ 13,192 ​ $ 81,679 ​ $ 29,078 Weighted-average common shares ​ 60,544 ​ 59,712 ​ 60,366 ​ 59,458 Basic earnings per share ​ $ 0.69 ​ $ 0.22 ​ $ 1.35 ​ $ 0.49 Diluted earnings per share: (1) ​ ​ ​ ​ Net income ​ $ 41,881 ​ $ 13,192 ​ $ 81,679 ​ $ 29,078 Weighted-average common shares ​ 60,544 ​ 59,712 ​ 60,366 ​ 59,458 Effect of dilutive awards: ​ ​ ​ ​ Employee stock plans ​ 922 ​ 912 ​ 1,115 ​ 1,006 Diluted weighted-average common shares ​ 61,466 ​ 60,624 ​ 61,481 ​ 60,464 Diluted earnings per share ​ $ 0.68 ​ $ 0.22 ​ $ 1.33 ​ $ 0.48 ​ (1) The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has excluded the shares underlying the outstanding performance-based awards in the 2021 and 2020 calculations as the shares were not contingently issuable as of the end of the reporting periods. In the three months ended June 30, 2021, approximately 134,000 stock awards were determined to be anti-dilutive and therefore excluded from the computation of diluted earnings per share, no outstanding stock awards were determined to be anti-dilutive in the comparable period of 2020. In the six months ended June 30, 2021 and 2020, no outstanding stock awards were determined to be anti-dilutive and therefore excluded from the computation of diluted earnings per share. In July 2020, the Company’s board of directors approved a two-for-one stock split in the form of a stock dividend to stockholders of record as of the close of business on August 14, 2020. Refer to Note 8, Stockholders’ Equity

PROVISION FOR INCOME TAXES

PROVISION FOR INCOME TAXES	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
PROVISION FOR INCOME TAXES	10. PROVISION FOR INCOME TAXES: Income-tax expense includes a provision for federal, state and foreign taxes based on the annual estimated effective tax rate applicable to the Company and its subsidiaries, adjusted for certain discrete items which are fully recognized in the period they occur. Accordingly, the interim effective tax rate may not be reflective of the annual estimated effective tax rate. The Company’s effective tax rates for the three and six months ended June 30, 2021, were 7.2% and 4.9%, respectively, and 8.4% and 7.0%, respectively, in the corresponding periods of 2020. In the three and six months ended June 30, 2021 and 2020, the effective tax rate was lower than the statutory federal income-tax rate of 21% due to the geographic distribution of the Company’s world-wide earnings in lower-tax jurisdictions, federal research tax credits and the recognition of excess tax benefits related to share-based payments. Additionally, in the six months ended June 30, 2021, the Company’s effective tax rate was favorably impacted by a discrete item associated with the release of an unrecognized tax benefit. These benefits were partially offset by foreign income subject to U.S. tax, known as global intangible low-taxed income. The Company’s primary jurisdiction where foreign earnings are derived is the Cayman Islands, which is a non-taxing jurisdiction. Income earned in other foreign jurisdictions was not material. The Company has not been granted any incentivized tax rates and does not operate under any tax holidays in any jurisdiction. As of June 30, 2021, the Company maintained a valuation allowance on its California deferred tax assets, New Jersey deferred tax assets, and capital losses for federal purposes, and a valuation allowance with respect to its deferred tax assets relating to tax credits in Canada. Determining the consolidated provision for income-tax expense, income-tax liabilities and deferred tax assets and liabilities involves judgment. The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates, which involves estimating current tax exposures as well as making judgments regarding the recoverability of deferred tax assets in each jurisdiction. The estimates used could differ from actual results, which may have a significant impact on operating results in future periods.

COMMITMENTS

COMMITMENTS	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS	11. COMMITMENTS: Supplier Agreements Under the terms of the Company’s wafer-supply agreements with Seiko Epson Corporation ("Epson"), and ROHM Lapis Semiconductor Co., Ltd. ("Lapis") the wafers purchased from these suppliers are priced in U.S. dollars, with mutual sharing of the impact of fluctuations in the exchange rate between the Japanese yen and the U.S. dollar on future purchases. Each year, the Company’s management and these two suppliers review and negotiate future pricing; the negotiated pricing is denominated in U.S. dollars but is subject to contractual exchange rate provisions. The fluctuation in the exchange rate is shared equally between the Company and each of these suppliers on future purchases.

LEGAL PROCEEDINGS AND CONTINGEN

LEGAL PROCEEDINGS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
LEGAL PROCEEDINGS AND CONTINGENCIES	12. LEGAL PROCEEDINGS AND CONTINGENCIES: From time to time in the ordinary course of business, the Company becomes involved in lawsuits, or customers and distributors may make claims against the Company. In accordance with ASC 450-10, Contingencies On April 1, 2016, Opticurrent, LLC filed a complaint against the Company in the United States District Court for the Eastern District of Texas alleging that the Company infringed one patent pertaining to transistor switch devices and seeking damages for the alleged infringement. The Company filed a motion to transfer the case to the Northern District of challenge to the order staying execution pending appeal. As such, the Company continues to believe it has strong defenses, and intends to continue to vigorously defend itself against Opticurrent’s claims. On June 19, 2019, Opticurrent, LLC filed a follow-on lawsuit in the United States District Court for the Northern District of California accusing more of the Company’s products of infringement and seeking damages for the alleged infringement of the same claim of the same patent asserted in the parties’ prior litigation, as described above. Limited discovery has taken place, but proceedings are currently stayed for all but written discovery, and no schedule has yet been set for expert discovery, dispositive motions, or trial. The Company believes it has strong defenses, independent of the issue on appeal in the first case, and intends to vigorously defend itself against Opticurrent’s claims, with appeals to follow if necessary. , The Company is unable to predict the outcome of legal proceedings with certainty, and there can be no assurance that the Company will prevail in the above-mentioned unsettled litigations. These litigations, whether or not determined in the Company’s favor or settled, will be costly and will divert the efforts and attention of the Company’s management and technical personnel from normal business operations, potentially causing a material adverse effect on the business, financial condition and operating results. Currently, the Company is not able to estimate a loss or a range of loss for the ongoing litigation disclosed above, however adverse determinations in litigation could result in monetary losses, the loss of proprietary rights, subject the Company to significant liabilities, require the Company to seek licenses from third parties or prevent the Company from licensing the technology, any of which could have a material adverse effect on the Company’s business, financial condition and operating results.

INDEMNIFICATIONS

INDEMNIFICATIONS	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
INDEMNIFICATIONS	13. INDEMNIFICATIONS: The Company sells products to its distributors under contracts, collectively referred to as Distributor Sales Agreements (“DSA”). Each DSA contains the relevant terms of the contractual arrangement with the distributor, and generally includes certain provisions for indemnifying the distributor against losses, expenses, and liabilities from damages that may be awarded against the distributor in the event the Company’s products are found to infringe upon a patent, copyright, trademark, or other proprietary right of a third party (“Customer Indemnification”). The DSA generally limits the scope of and remedies for the Customer Indemnification obligations in a variety of industry-standard respects, including, but not limited to, limitations based on time and geography, and a right to replace an infringing product. The Company also, from time to time, has granted a specific indemnification right to individual customers. The Company believes its internal development processes and other policies and practices limit its exposure related to such indemnifications. In addition, the Company requires its employees to sign a proprietary information and inventions agreement, which assigns the rights to its employees’ development work to the Company. To date, the Company has not had to reimburse any of its distributors or customers for any losses related to these indemnifications and no material claims were outstanding as of June 30, 2021. For several reasons, including the lack of prior indemnification claims and the lack of a monetary liability limit for certain infringement cases, the Company cannot determine the maximum amount of potential future payments, if any, related to such indemnifications.

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies And Recent Accounting Pronouncements [Abstract]
Significant Accounting Policies and Estimates	Significant Accounting Policies and Estimates No material changes have been made to the Company’s significant accounting policies disclosed in Note 2, Significant Accounting Policies and Recent Accounting Pronouncements
Recent Accounting Pronouncements	Recent Accounting Pronouncements The Company has considered all recent accounting pronouncements issued, but not yet effective, and does not expect any to have a material effect on the Company’s condensed consolidated financial statements.

COMPONENTS OF THE COMPANY'S C_2

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS (Tables)	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Accounts Receivable	Accounts Receivable ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, (In thousands) ​ 2021 ​ 2020 Accounts receivable trade ​ $ 78,759 ​ $ 66,703 Allowance for ship and debit ​ (33,738) ​ (26,435) Allowance for stock rotation and rebate ​ (3,151) ​ (3,931) Allowance for credit losses ​ ​ (518) ​ ​ (427) Total ​ $ 41,352 ​ $ 35,910
Schedule of Allowance for Credit Losses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) ​ 2021 2020 2021 2020 Beginning balance ​ $ (425) ​ $ (609) ​ $ (427) ​ $ (763) Provision for credit loss expense ​ (360) ​ — ​ (577) ​ — Receivables written off ​ — ​ — ​ — ​ 154 Recoveries collected ​ 267 ​ — ​ 486 ​ — Ending balance ​ $ (518) ​ $ (609) ​ $ (518) ​ $ (609)
Schedule of Inventory, Current	Inventories ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, (In thousands) ​ 2021 ​ 2020 Raw materials ​ $ 23,285 ​ $ 32,131 Work-in-process ​ 35,488 ​ 39,469 Finished goods ​ 30,870 ​ 31,278 Total ​ $ 89,643 ​ $ 102,878
Schedule Of Intangible Assets	Intangible Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ (In thousands) ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Domain name ​ $ 1,261 ​ $ — ​ $ 1,261 ​ $ 1,261 ​ $ — ​ $ 1,261 Developed technology ​ 37,960 ​ (30,500) ​ 7,460 ​ 37,960 ​ (29,126) ​ 8,834 Customer relationships ​ 16,700 ​ (16,095) ​ 605 ​ 16,700 ​ (15,687) ​ 1,013 Technology licenses ​ 1,926 ​ (651) ​ 1,275 ​ 1,926 ​ (528) ​ 1,398 Total intangible assets ​ $ 57,847 ​ $ (47,246) ​ $ 10,601 ​ $ 57,847 ​ $ (45,341) ​ $ 12,506
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated future amortization expense related to finite-lived intangible assets at June 30, 2021, is as follows: ​ ​ ​ ​ ​ Estimated ​ ​ Amortization Fiscal Year ​ (In thousands) 2021 (remaining six months) ​ $ 1,589 2022 ​ 2,415 2023 ​ 2,173 2024 ​ 1,279 2025 ​ 832 Thereafter ​ 1,052 Total ​ $ 9,340
Schedule of Accumulated Other Comprehensive Loss	Changes in accumulated other comprehensive loss for the three and six months ended June 30, 2021 and 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ Defined Benefit ​ Foreign Currency ​ ​ ​ ​ Marketable Securities ​ Pension Items ​ Items ​ Total ​ Three Months Ended ​ Three Months Ended ​ Three Months Ended ​ Three Months Ended ​ June 30, ​ June 30, ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 2021 2020 2021 2020 Beginning balance $ 310 ​ $ (369) ​ $ (1,716) ​ $ (2,433) ​ $ (1,430) ​ $ (1,512) ​ $ (2,836) ​ $ (4,314) Other comprehensive income (loss) before reclassifications (331) ​ 2,566 ​ — ​ — ​ (40) ​ (30) ​ (371) ​ 2,536 Amounts reclassified from accumulated other comprehensive loss — ​ — ​ 52 (1) 58 (1) — ​ — ​ 52 ​ 58 Net-current period other comprehensive income (loss) (331) ​ 2,566 ​ 52 ​ 58 ​ (40) ​ (30) ​ (319) ​ 2,594 Ending balance $ (21) ​ $ 2,197 ​ $ (1,664) ​ $ (2,375) ​ $ (1,470) ​ $ (1,542) ​ $ (3,155) ​ $ (1,720) ​ (1) This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the three months ended June 30, 2021 and 2020. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ Defined Benefit Pension ​ Foreign Currency ​ ​ ​ ​ Marketable Securities ​ Items ​ Items ​ Total ​ Six Months Ended ​ Six Months Ended ​ Six Months Ended ​ Six Months Ended ​ June 30, ​ June 30, ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 ​ 2020 2021 2020 2021 2020 Beginning balance $ 890 ​ $ 583 ​ $ (1,641) ​ $ (2,484) ​ $ (1,412) ​ $ (1,229) ​ $ (2,163) ​ $ (3,130) Other comprehensive income (loss) before reclassifications (911) ​ 1,614 ​ — ​ — ​ (58) ​ (313) ​ (969) ​ 1,301 Amounts reclassified from accumulated other comprehensive loss — ​ — ​ (23) (1) 109 (1) — ​ — ​ (23) ​ 109 Net-current period other comprehensive income (loss) (911) ​ 1,614 ​ (23) ​ 109 ​ (58) ​ (313) ​ (992) ​ 1,410 Ending balance $ (21) ​ $ 2,197 ​ $ (1,664) ​ $ (2,375) ​ $ (1,470) ​ $ (1,542) ​ $ (3,155) ​ $ (1,720) (1) This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the six months ended June 30, 2021 and 2020.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair value of marketable securities and investments	The fair-value hierarchy of the Company’s cash equivalents and marketable securities at June 30, 2021, and December 31, 2020, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ June 30, 2021 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 341,013 ​ $ — ​ $ 341,013 Corporate securities ​ ​ 107,780 ​ ​ — ​ ​ 107,780 Money market funds ​ 1,865 ​ 1,865 ​ — Total ​ $ 450,658 ​ $ 1,865 ​ $ 448,793 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2020 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Corporate securities ​ $ 146,658 ​ $ — ​ $ 146,658 Commercial paper ​ 253,855 ​ — ​ 253,855 Money market funds ​ 1,634 ​ 1,634 ​ — Total ​ $ 402,147 ​ $ 1,634 ​ $ 400,513

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	6 Months Ended
	Jun. 30, 2021
Marketable Securities [Abstract]
Available-for-sale Securities	Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at June 30, 2021, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 77,195 ​ $ — ​ $ — ​ $ 77,195 Corporate securities ​ ​ 23,948 ​ ​ 46 ​ ​ (6) ​ ​ 23,988 Total ​ 101,143 ​ 46 ​ (6) ​ 101,183 Investments due in 4-12 months: ​ ​ ​ ​ Commercial paper ​ ​ 34,306 ​ ​ — ​ ​ — ​ ​ 34,306 Corporate securities ​ 20,675 ​ 47 ​ (5) ​ 20,717 Total ​ 54,981 ​ 47 ​ (5) ​ 55,023 Investments due in 12 months or greater: ​ ​ ​ ​ Corporate securities ​ 61,674 ​ — ​ (103) ​ 61,571 Total ​ ​ 61,674 ​ — ​ ​ (103) ​ 61,571 Total marketable securities ​ $ 217,798 ​ $ 93 ​ $ (114) ​ $ 217,777 Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 43,660 ​ $ — ​ $ — ​ $ 43,660 Corporate securities ​ ​ 19,846 ​ ​ 44 ​ ​ — ​ ​ 19,890 Total ​ 63,506 ​ 44 ​ — ​ 63,550 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 125,922 ​ 846 ​ — ​ 126,768 Total ​ 125,922 ​ 846 ​ — ​ 126,768 Total marketable securities ​ $ 189,428 ​ $ 890 ​ $ — ​ $ 190,318
Available-for-sale Securities in an Unrealized Loss Position	The following table summarizes marketable securities classified as available-for-sale (excluding cash equivalents) in a continuous unrealized loss position for which an allowance for credit losses was not recorded at June 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less Than 12 Months ​ 12 Months or Longer ​ Total ​ Estimated Gross Estimated Gross Estimated Gross ​ ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized (In thousands) ​ Value ​ Losses ​ Value ​ Losses ​ Value ​ Losses Corporate securities ​ $ 69,194 ​ $ (114) ​ $ — ​ $ — ​ $ 69,194 ​ $ (114) Total marketable securities ​ $ 69,194 ​ $ (114) ​ $ — ​ $ — ​ $ 69,194 ​ $ (114)

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation Expense	The following table summarizes the stock-based compensation expense recognized in accordance with ASC 718-10 for the three and six months ended June 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 Cost of revenues ​ $ 640 ​ $ 252 ​ $ 1,271 ​ $ 648 Research and development ​ 3,159 ​ 2,351 ​ 5,550 ​ 4,460 Sales and marketing ​ 1,725 ​ 1,258 ​ 3,339 ​ 2,650 General and administrative ​ 3,676 ​ 2,120 ​ 7,520 ​ 4,933 Total stock-based compensation expense ​ $ 9,200 ​ $ 5,981 ​ $ 17,680 ​ $ 12,691
Summary of Option Activity Under the Plans	A summary of stock options outstanding as of June 30, 2021, and activity during the six months then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ ​ ​ Average ​ Contractual ​ Aggregate ​ ​ Shares ​ Exercise ​ Term ​ Intrinsic Value ​ (In thousands) Price (In years) (In thousands) Outstanding at January 1, 2021 92 ​ $ 20.63 ​ ​ ​ Granted — ​ — ​ Exercised (33) ​ $ 19.15 ​ Forfeited or expired — ​ — ​ Outstanding at June 30, 2021 59 ​ $ 21.44 0.85 ​ $ 3,602 Vested and exercisable at June 30, 2021 59 ​ ​ ​ 0.85 ​ $ 3,602
Performance Based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of PSUs outstanding as of June 30, 2021, and activity during the six months ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 150 ​ $ 46.27 ​ ​ ​ Granted 100 ​ $ 84.45 ​ Vested (150) ​ $ 46.27 ​ Forfeited — ​ ​ — ​ Outstanding at June 30, 2021 100 ​ $ 84.45 0.50 ​ $ 8,228 Outstanding and expected to vest at June 30, 2021 100 ​ ​ ​ 0.50 ​ $ 8,228
Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of PRSUs outstanding as of June 30, 2021, and activity during the six months ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 301 ​ $ 41.90 ​ ​ ​ Granted 97 ​ $ 83.00 ​ Vested (6) ​ $ 29.95 ​ Forfeited (15) ​ $ 40.05 ​ Outstanding at June 30, 2021 377 ​ $ 52.75 1.40 ​ $ 30,956 Outstanding and expected to vest at June 30, 2021 377 ​ ​ ​ 1.40 ​ $ 30,956
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of RSUs outstanding as of June 30, 2021, and activity during the six months then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2021 1,518 ​ $ 35.51 ​ ​ ​ Granted 227 ​ $ 82.94 ​ Vested (524) ​ $ 34.53 ​ Forfeited (71) ​ $ 36.41 ​ Outstanding at June 30, 2021 1,150 ​ $ 45.29 1.70 ​ $ 94,342 Outstanding and expected to vest at June 30, 2021 1,064 ​ ​ ​ 1.65 ​ $ 87,279

SIGNIFICANT CUSTOMERS AND GEO_2

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES (Tables)	6 Months Ended
	Jun. 30, 2021
Concentration Risk [Line Items]
Geographic Net Revenues	The Company markets its products globally through its sales personnel and a worldwide network of independent sales representatives and distributors. Geographic net revenues, based on “bill to” customer locations, for the three and six months ended June 30, 2021 and 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 United States of America ​ $ 3,819 ​ $ 2,935 ​ $ 7,919 ​ $ 5,648 Hong Kong/China ​ 122,123 ​ 65,680 ​ 240,853 ​ 126,093 Taiwan ​ 6,361 ​ 7,199 ​ 12,803 ​ 13,678 Korea ​ 13,705 ​ 7,284 ​ 26,194 ​ 17,641 Western Europe (excluding Germany) ​ 8,720 ​ 7,995 ​ 15,850 ​ 18,030 Japan ​ 5,152 ​ 4,398 ​ 9,799 ​ 8,303 Germany ​ 7,656 ​ 5,847 ​ 14,662 ​ 11,414 Other ​ 12,574 ​ 5,494 ​ 25,767 ​ 15,689 Total net revenues ​ $ 180,110 ​ $ 106,832 ​ $ 353,847 ​ $ 216,496
Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Schedules of Concentration of Risk, by Risk Factor	The following customers represented 10% or more of the Company’s net revenues for the respective periods: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, ​ June 30, Customer ​ 2021 ​ 2020 ​ 2021 ​ 2020 Avnet 29 % ​ 13 % 30 % ​ 12 % Honestar Technologies Co., Ltd. ​ 19 % ​ * ​ ​ 19 % ​ * ​ ​ * Total customer revenue was less than 10% of net revenues.
Accounts Receivable [Member]
Concentration Risk [Line Items]
Schedules of Concentration of Risk, by Risk Factor	The following customers represented 10% or more of accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, Customer 2021 ​ 2020 Avnet ​ 46 % ​ 50 % Powertech Distribution Ltd. * ​ ​ 10 % * Total customer accounts receivable was less than 10% of accounts receivable.

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Schedule of Common Stock Shares Outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands) 2021 2020 2021 2020 Beginning balance ​ ​ 60,363 ​ ​ 59,382 ​ ​ 59,910 ​ ​ 58,862 Common stock issued under employee stock plans ​ 316 ​ 386 ​ 769 ​ 954 Repurchased ​ (335) ​ (16) ​ (335) ​ (64) Ending balance ​ ​ 60,344 ​ ​ 59,752 ​ ​ 60,344 ​ ​ 59,752
Schedule of Dividends Declared and Paid	For the three and six months ended June 30, 2021 and 2020, cash dividends declared and paid were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands, except per share amounts) 2021 2020 2021 2020 Dividends declared and paid ​ $ 7,867 ​ $ 6,271 ​ $ 15,712 ​ $ 11,915 Dividends declared per common share ​ $ 0.13 ​ $ 0.105 ​ $ 0.26 ​ $ 0.20

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings per share calculation	A summary of the earnings per share calculation is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, (In thousands, except per share amounts) 2021 2020 2021 2020 Basic earnings per share: ​ ​ ​ ​ Net income ​ $ 41,881 ​ $ 13,192 ​ $ 81,679 ​ $ 29,078 Weighted-average common shares ​ 60,544 ​ 59,712 ​ 60,366 ​ 59,458 Basic earnings per share ​ $ 0.69 ​ $ 0.22 ​ $ 1.35 ​ $ 0.49 Diluted earnings per share: (1) ​ ​ ​ ​ Net income ​ $ 41,881 ​ $ 13,192 ​ $ 81,679 ​ $ 29,078 Weighted-average common shares ​ 60,544 ​ 59,712 ​ 60,366 ​ 59,458 Effect of dilutive awards: ​ ​ ​ ​ Employee stock plans ​ 922 ​ 912 ​ 1,115 ​ 1,006 Diluted weighted-average common shares ​ 61,466 ​ 60,624 ​ 61,481 ​ 60,464 Diluted earnings per share ​ $ 0.68 ​ $ 0.22 ​ $ 1.33 ​ $ 0.48 ​ (1) The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has excluded the shares underlying the outstanding performance-based awards in the 2021 and 2020 calculations as the shares were not contingently issuable as of the end of the reporting periods.

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details)	Aug. 18, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Stock split ratio	2

COMPONENTS OF THE COMPANY'S C_3

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Accounts receivable trade	$ 78,759		$ 66,703
Allowance for ship and debit	(33,738)		(26,435)
Allowance for stock rotation and rebate	(3,151)		(3,931)
Allowance for credit losses	(518)	$ (425)	(427)	$ (609)	$ (609)	$ (763)
Total	$ 41,352		$ 35,910

COMPONENTS OF THE COMPANY'S C_4

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Beginning Balance	$ (425)	$ (609)	$ (427)	$ (763)
Provision for credit loss expense	(360)	0	(577)	0
Receivables written off	0	0	0	154
Recoveries collected	267	0	486	0
Ending Balance	$ (518)	$ (609)	$ (518)	$ (609)

COMPONENTS OF THE COMPANY'S C_5

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 23,285	$ 32,131
Work-in-process	35,488	39,469
Finished goods	30,870	31,278
Total	$ 89,643	$ 102,878

COMPONENTS OF THE COMPANY'S C_6

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Intangible Assets Table [Line Items]
Intangible Assets, Gross	$ 57,847	$ 57,847
Accumulated Amortization	(47,246)	(45,341)
Finite-Lived Intangible Assets, Net	9,340
Total Intangible Assets, Net	10,601	12,506
Developed technology
Schedule of Intangible Assets Table [Line Items]
Finite-Lived Intangible Assets, Gross	37,960	37,960
Accumulated Amortization	(30,500)	(29,126)
Finite-Lived Intangible Assets, Net	7,460	8,834
Customer relationships
Schedule of Intangible Assets Table [Line Items]
Finite-Lived Intangible Assets, Gross	16,700	16,700
Accumulated Amortization	(16,095)	(15,687)
Finite-Lived Intangible Assets, Net	605	1,013
Technology licenses
Schedule of Intangible Assets Table [Line Items]
Finite-Lived Intangible Assets, Gross	1,926	1,926
Accumulated Amortization	(651)	(528)
Finite-Lived Intangible Assets, Net	1,275	1,398
Domain Name
Schedule of Intangible Assets Table [Line Items]
Indefinite-Lived Intangible Assets	1,261	1,261
Accumulated Amortization	$ 0	$ 0

COMPONENTS OF THE COMPANY'S C_7

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Future Amortization Expense (Details) $ in Thousands	Jun. 30, 2021USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2021 (remaining six months)	$ 1,589
2022	2,415
2023	2,173
2024	1,279
2025	832
Thereafter	1,052
Total	$ 9,340

COMPONENTS OF THE COMPANY'S C_8

COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (2,836)	$ (4,314)	$ (2,163)	$ (3,130)
Other comprehensive income (loss) before reclassifications	(371)	2,536	(969)	1,301
Amounts reclassified from accumulated other comprehensive income (loss)	52	58	(23)	109
Net-current period other comprehensive income (loss)	(319)	2,594	(992)	1,410
Ending balance	(3,155)	(1,720)	(3,155)	(1,720)
Unrealized Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	310	(369)	890	583
Other comprehensive income (loss) before reclassifications	(331)	2,566	(911)	1,614
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net-current period other comprehensive income (loss)	(331)	2,566	(911)	1,614
Ending balance	(21)	2,197	(21)	2,197
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,716)	(2,433)	(1,641)	(2,484)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	52	58	(23)	109
Net-current period other comprehensive income (loss)	52	58	(23)	109
Ending balance	(1,664)	(2,375)	(1,664)	(2,375)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,430)	(1,512)	(1,412)	(1,229)
Other comprehensive income (loss) before reclassifications	(40)	(30)	(58)	(313)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net-current period other comprehensive income (loss)	(40)	(30)	(58)	(313)
Ending balance	$ (1,470)	$ (1,542)	$ (1,470)	$ (1,542)

FAIR VALUE MEASUREMENTS Fair Va

FAIR VALUE MEASUREMENTS Fair Value Measurement (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	$ 450,658	$ 402,147
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	341,013	253,855
Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	107,780	146,658
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	1,865	1,634
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	1,865	1,634
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	1,865	1,634
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	448,793	400,513
Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	341,013	253,855
Significant Other Observable Inputs (Level 2) | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	107,780	146,658
Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	$ 0	$ 0

MARKETABLE SECURITIES Marketabl

MARKETABLE SECURITIES Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Interest receivable	$ 600	$ 800
Amortized Cost	217,798	189,428
Gross Unrealized Gains	93	890
Gross Unrealized Losses	(114)	0
Estimated Fair Market Value	217,777	190,318
Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	101,143	63,506
Gross Unrealized Gains	46	44
Gross Unrealized Losses	(6)	0
Estimated Fair Market Value	101,183	63,550
Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	54,981	125,922
Gross Unrealized Gains	47	846
Gross Unrealized Losses	(5)	0
Estimated Fair Market Value	55,023	126,768
Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	61,674
Gross Unrealized Gains	0
Gross Unrealized Losses	(103)
Estimated Fair Market Value	61,571
Commercial paper | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	77,195	43,660
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	77,195	43,660
Commercial paper | Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	34,306
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Market Value	34,306
Corporate securities | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,948	19,846
Gross Unrealized Gains	46	44
Gross Unrealized Losses	(6)	0
Estimated Fair Market Value	23,988	19,890
Corporate securities | Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20,675	125,922
Gross Unrealized Gains	47	846
Gross Unrealized Losses	(5)	0
Estimated Fair Market Value	20,717	$ 126,768
Corporate securities | Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	61,674
Gross Unrealized Gains	0
Gross Unrealized Losses	(103)
Estimated Fair Market Value	$ 61,571

MARKETABLE SECURITIES - Continu

MARKETABLE SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months Estimated Fair Market Value, Total marketable securities	$ 69,194,000		$ 69,194,000
Less Than 12 Months Gross Unrealized Losses, Total marketable securities	(114,000)		(114,000)
12 Months or Longer Estimated Fair Market Value, Total marketable securities	0		0
12 Months or Longer Gross Unrealized Losses, Total marketable securities	0		0
Total Estimated Fair Market Value, Total marketable securities	69,194,000		69,194,000
Total Gross Unrealized Losses, Total marketable securities	(114,000)		(114,000)
Unrealized losses on marketable securities	0	$ 0	0	$ 0
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months Estimated Fair Market Value, Total marketable securities	69,194,000		69,194,000
Less Than 12 Months Gross Unrealized Losses, Total marketable securities	(114,000)		(114,000)
12 Months or Longer Estimated Fair Market Value, Total marketable securities	0		0
12 Months or Longer Gross Unrealized Losses, Total marketable securities	0		0
Total Estimated Fair Market Value, Total marketable securities	69,194,000		69,194,000
Total Gross Unrealized Losses, Total marketable securities	$ (114,000)		$ (114,000)

STOCK-BASED COMPENSATION Stock-

STOCK-BASED COMPENSATION Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 9,200	$ 5,981	$ 17,680	$ 12,691
Performance Based Awards and Long Term Performance based Units
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	4,000	1,100	6,700	2,400
Restricted Stock Units (RSUs)
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	4,700	4,500	10,000	9,500
Employee Stock Purchase Plan
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	500	400	1,000	800
Cost of revenues
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	640	252	1,271	648
Research and development
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	3,159	2,351	5,550	4,460
Sales and marketing
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,725	1,258	3,339	2,650
General and administrative
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 3,676	$ 2,120	$ 7,520	$ 4,933

STOCK-BASED COMPENSATION Option

STOCK-BASED COMPENSATION Option Activity (Details) - Stock Options $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Option activity under the Plans
Outstanding at January 1, 2021	92
Granted	0
Exercised	(33)
Forfeited or expired	0
Outstanding at June 30, 2021	59
Vested and exercisable at June 30, 2021	59
Weighted- Average Exercise Price (in dollars per share)
Outstanding at January 1, 2021 | $ / shares	$ 20.63
Granted | $ / shares	0
Exercised | $ / shares	19.15
Forfeited or expired | $ / shares	0
Outstanding at June 30, 2021 | $ / shares	$ 21.44
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2021	10 months 6 days
Vested and exercisable at June 30, 2021	10 months 6 days
Aggregate Intrinsic Value [Abstract]
Outstanding at June 30, 2021 | $	$ 3,602
Vested and exercisable at June 30, 2021 | $	$ 3,602

STOCK-BASED COMPENSATION Perfor

STOCK-BASED COMPENSATION Performance-based Awards and Restricted Stock Units (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Restricted Stock Units (RSUs)
Shares
Outstanding at January 1, 2021	1,518,000
Granted	227,000
Vested	(524,000)
Forfeited	(71,000)
Outstanding at June 30, 2021	1,150,000
Outstanding and expected to vest at June 30, 2021	1,064,000
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2021 | $ / shares	$ 35.51
Granted | $ / shares	82.94
Vested | $ / shares	34.53
Forfeited | $ / shares	36.41
Outstanding at June 30, 2021 | $ / shares	$ 45.29
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2021	1 year 8 months 12 days
Outstanding and expected to vest at June 30, 2021	1 year 7 months 24 days
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2021 | $	$ 94,342
Outstanding and expected to vest at June 30, 2021 | $	$ 87,279
Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based period	3 years
Shares
Outstanding at January 1, 2021	301,000
Granted	97,000
Vested	(6,000)
Forfeited	(15,000)
Outstanding at June 30, 2021	377,000
Outstanding and expected to vest at June 30, 2021	377,000
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2021 | $ / shares	$ 41.90
Granted | $ / shares	83
Vested | $ / shares	29.95
Forfeited | $ / shares	40.05
Outstanding at June 30, 2021 | $ / shares	$ 52.75
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2021	1 year 4 months 24 days
Outstanding and expected to vest at June 30, 2021	1 year 4 months 24 days
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2021 | $	$ 30,956
Outstanding and expected to vest at June 30, 2021 | $	$ 30,956
Performance Based Awards (PSUs)
Shares
Outstanding at January 1, 2021	150,000
Granted	100,000
Vested	(150,000)
Forfeited	0
Outstanding at June 30, 2021	100,000
Outstanding and expected to vest at June 30, 2021	100,000
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2021 | $ / shares	$ 46.27
Granted | $ / shares	84.45
Vested | $ / shares	46.27
Forfeited | $ / shares	0
Outstanding at June 30, 2021 | $ / shares	$ 84.45
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2021	6 months
Outstanding and expected to vest at June 30, 2021	6 months
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2021 | $	$ 8,228
Outstanding and expected to vest at June 30, 2021 | $	$ 8,228
Minimum [Member] | Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	0.00%
Minimum [Member] | Performance Based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	0.00%
Maximum [Member] | Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	200.00%
Maximum [Member] | Performance Based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	200.00%

SIGNIFICANT CUSTOMERS AND GEO_3

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES Customer and Credit Risk Concentration (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021USD ($)customer	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segmentcustomer	Jun. 30, 2020USD ($)	Dec. 31, 2020customer
Concentration Risk [Line Items]
Number of reportable segments | segment			1
NET REVENUES | $	$ 180,110	$ 106,832	$ 353,847	$ 216,496
Distributors [Member]
Concentration Risk [Line Items]
NET REVENUES | $	$ 136,400	$ 87,300	$ 270,700	$ 170,800
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Number of major customers | customer	10		10
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk [Member] | Avnet
Concentration Risk [Line Items]
Concentration risk, percentage of total net revenues	29.00%	13.00%	30.00%	12.00%
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk [Member] | Honestar Technologies Co., Ltd.
Concentration Risk [Line Items]
Concentration risk percentage	19.00%		19.00%
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk [Member] | Ten Customers
Concentration Risk [Line Items]
Concentration risk, percentage of total net revenues	80.00%	59.00%	80.00%	56.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Number of major customers | customer			10		10
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Avnet
Concentration Risk [Line Items]
Concentration risk percentage			46.00%		50.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Powertech Distribution Ltd.
Concentration Risk [Line Items]
Concentration risk percentage					10.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Ten Customers
Concentration Risk [Line Items]
Concentration risk percentage			84.00%		90.00%

SIGNIFICANT CUSTOMERS AND GEO_4

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES Geographic Net Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue by Geography
Total net revenues	$ 180,110	$ 106,832	$ 353,847	$ 216,496
United States of America
Revenue by Geography
Total net revenues	3,819	2,935	7,919	5,648
Hong Kong/China
Revenue by Geography
Total net revenues	122,123	65,680	240,853	126,093
Taiwan
Revenue by Geography
Total net revenues	6,361	7,199	12,803	13,678
Korea
Revenue by Geography
Total net revenues	13,705	7,284	26,194	17,641
Western Europe (excluding Germany)
Revenue by Geography
Total net revenues	8,720	7,995	15,850	18,030
Japan
Revenue by Geography
Total net revenues	5,152	4,398	9,799	8,303
Germany
Revenue by Geography
Total net revenues	7,656	5,847	14,662	11,414
Other
Revenue by Geography
Total net revenues	$ 12,574	$ 5,494	$ 25,767	$ 15,689

STOCKHOLDERS' EQUITY Common Sto

STOCKHOLDERS' EQUITY Common Stock Shares Outstanding (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Common Stock Shares Outstanding [Abstract]
Beginning balance	60,363,000	59,382,000	59,910,000	58,862,000
Common stock issued under employee stock plans	316,000	386,000	769,000	954,000
Repurchased	(335,000)	(16,000)	(335,000)	(64,000)
Ending balance	60,344,000	59,752,000	60,344,000	59,752,000

STOCKHOLDERS' EQUITY Common S_2

STOCKHOLDERS' EQUITY Common Stock Repurchases (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Apr. 27, 2021	Dec. 31, 2020
Stockholders' Equity Attributable to Parent [Abstract]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 64.9		$ 64.9		$ 50	$ 41.3
Repurchase of common stock (shares)	335,000	16,000	335,000	64,000
Repurchase of common stock			$ 26.4

STOCKHOLDERS' EQUITY Dividends

STOCKHOLDERS' EQUITY Dividends (Details)	Aug. 18, 2020	Jan. 31, 2021item$ / shares	Jul. 31, 2020USD ($)$ / shares	Apr. 30, 2020USD ($)$ / shares	Oct. 31, 2019USD ($)$ / shares	Jun. 30, 2021USD ($)$ / shares	Jun. 30, 2020USD ($)$ / shares	Jun. 30, 2021USD ($)$ / shares	Jun. 30, 2020USD ($)$ / shares
Dividends Declared and Paid [Line Items]
Stock split ratio	2
Dividends declared and paid | $						$ 7,867,000	$ 6,271,000	$ 15,712,000	$ 11,915,000
Dividends declared per common share						$ 0.13	$ 0.105	$ 0.26	$ 0.20
Common Stock, Dividends, Number of Quarterly Distributions Declared		4	2	3	4
Common Stock, Dividends, Per Share, Declared, Prior Fiscal Year, Each Quarter					$ 0.095
Common Stock, Dividends Per Share Declared, Prior Fiscal Year, Second Quarter				$ 0.105
Common Stock, Dividends Per Share Declared, Prior Fiscal Year, Third Quarter			$ 0.11	0.105
Common Stock, Dividends Per Share Declared, Prior Fiscal Year, Fourth Quarter			$ 0.11	$ 0.105
Common Stock, Dividends, Increase Per Share, Declared, Current Fiscal Year, Each Quarter		$ 0.02
Common Stock, Dividends, Per Share, Declared, Current Fiscal Year, Each Quarter		$ 0.13
Common Stock
Dividends Declared and Paid [Line Items]
Stock split ratio	2
Dividends Payable, Date to be Paid			Aug. 18, 2020
Dividends Payable, Date of Record			Aug. 14, 2020

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Aug. 18, 2020	Jun. 30, 2021USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2021USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares
Basic earnings per share:
Net income | $		$ 41,881	$ 13,192	$ 81,679	$ 29,078
Weighted-average common shares		60,544	59,712	60,366	59,458
Basic earnings per share | $ / shares		$ 0.69	$ 0.22	$ 1.35	$ 0.49
Diluted earnings per share:
Net income | $		$ 41,881	$ 13,192	$ 81,679	$ 29,078
Weighted-average common shares		60,544	59,712	60,366	59,458
Effect of dilutive awards:
Employee stock plans		922	912	1,115	1,006
Diluted weighted-average common shares		61,466	60,624	61,481	60,464
Diluted earnings per share | $ / shares		$ 0.68	$ 0.22	$ 1.33	$ 0.48
Stock awards excluded in the computation of diluted earnings per share		134,000	0	0	0
Stock split ratio	2

PROVISION FOR INCOME TAXES (Det

PROVISION FOR INCOME TAXES (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Effective income tax rate	7.20%	8.40%	4.90%	7.00%
Federal statutory tax rate	21.00%	21.00%	21.00%	21.00%

LEGAL PROCEEDINGS AND CONTING_2

LEGAL PROCEEDINGS AND CONTINGENCIES (Details) - Pending Litigation [Member] $ in Millions	Jan. 06, 2020patent	Apr. 01, 2016patent	Feb. 28, 2019USD ($)	Jun. 30, 2020USD ($)
Patent Infringement Claim One
Gain and Loss Contingencies [Line Items]
Loss Contingency, Patents Allegedly Infringed, Number		1
Loss Contingency, Damages Awarded, Value | $			$ 6.7	$ 1.2
Patent Infringement Claim Two
Gain and Loss Contingencies [Line Items]
Gain Contingency, Patents Allegedly Infringed upon, Number	2