Monolithic Power Systems (MPWR) 10-Q 10 May 21 2021 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 03, 2021
Document Information [Line Items]
Entity Central Index Key	0001280452
Entity Registrant Name	MONOLITHIC POWER SYSTEMS INC
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	000-51026
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0466789
Entity Address, Address Line One	5808 Lake Washington Blvd. NE
Entity Address, City or Town	Kirkland
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98033
City Area Code	425
Local Phone Number	296-9956
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	MPWR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		45,754,000

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 218,368	$ 334,944
Short-term investments	420,455	260,169
Accounts receivable, net	84,059	66,843
Inventories	175,223	157,062
Other current assets	24,325	22,980
Total current assets	922,430	841,998
Property and equipment, net	297,741	281,528
Goodwill	6,571	6,571
Deferred tax assets, net	17,668	18,556
Other long-term assets	63,782	59,838
Total assets	1,308,192	1,208,491
Current liabilities:
Accounts payable	57,235	38,169
Accrued compensation and related benefits	56,307	45,840
Other accrued liabilities	74,367	62,960
Total current liabilities	187,909	146,969
Income tax liabilities	37,062	37,062
Other long-term liabilities	61,644	57,873
Total liabilities	286,615	241,904
Commitments and contingencies
Stockholders’ equity:
Common stock and additional paid-in capital: $0.001 par value; shares authorized: 150,000; shares issued and outstanding: 45,737 and 45,267, respectively	699,359	657,701
Retained earnings	315,206	298,746
Accumulated other comprehensive income	7,012	10,140
Total stockholders’ equity	1,021,577	966,587
Total liabilities and stockholders’ equity	$ 1,308,192	$ 1,208,491

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares shares in Thousands	Mar. 31, 2021	Dec. 31, 2020
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	150,000	150,000
Common stock, shares issued (in shares)	45,737	45,267
Common stock, shares outstanding (in shares)	45,737	45,267

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue	$ 254,455	$ 165,778
Cost of revenue	113,396	74,331
Gross profit	141,059	91,447
Operating expenses:
Research and development	41,892	25,956
Selling, general and administrative	51,453	32,164
Litigation expense	1,628	2,341
Total operating expenses	94,973	60,461
Income from operations	46,086	30,986
Other income (expense), net	2,587	(1,714)
Income before income taxes	48,673	29,272
Income tax expense (benefit)	3,260	(6,484)
Net income	$ 45,413	$ 35,756
Net income per share
Basic (in dollars per share)	$ 1	$ 0.80
Diluted (in dollars per share)	$ 0.95	$ 0.77
Weighted-average shares outstanding:
Basic (in shares)	45,498	44,455
Diluted (in shares)	47,711	46,670

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income	$ 45,413	$ 35,756
Other comprehensive loss, net of tax:
Foreign currency translation adjustments	(2,474)	(2,882)
Change in unrealized loss on available-for-sale securities, net of tax of $124 and $55, respectively	(654)	(1,653)
Other comprehensive loss, net of tax	(3,128)	(4,535)
Comprehensive income	$ 42,285	$ 31,221

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Change in unrealized gain (loss) on available-for-sale securities, tax	$ 124	$ 55

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2019	43,616
Balance at Dec. 31, 2019	$ 549,517	$ 229,450	$ (5,476)	$ 773,491
Net income	0	35,756	0	35,756
Other comprehensive loss	0	0	(4,535)	(4,535)
Dividends and dividend equivalents declared	$ 0	(23,741)	0	(23,741)
Common stock issued under the employee equity incentive plan (in shares)	1,084
Common stock issued under the employee equity incentive plan	$ 11,758	0	0	11,758
Common stock issued under the employee stock purchase plan (in shares)	15
Common stock issued under the employee stock purchase plan	$ 1,892	0	0	1,892
Stock-based compensation expense	$ 18,569	0	0	18,569
Balance (in shares) at Mar. 31, 2020	44,715
Balance at Mar. 31, 2020	$ 581,736	241,465	(10,011)	$ 813,190
Balance (in shares) at Dec. 31, 2020	45,267			45,267
Balance at Dec. 31, 2020	$ 657,701	298,746	10,140	$ 966,587
Net income	0	45,413	0	45,413
Other comprehensive loss	0	0	(3,128)	(3,128)
Dividends and dividend equivalents declared	$ 0	(28,953)	0	(28,953)
Common stock issued under the employee equity incentive plan (in shares)	460
Common stock issued under the employee equity incentive plan	$ 10,744	0	0	10,744
Common stock issued under the employee stock purchase plan (in shares)	10
Common stock issued under the employee stock purchase plan	$ 2,293	0	0	2,293
Stock-based compensation expense	$ 28,621	0	0	$ 28,621
Balance (in shares) at Mar. 31, 2021	45,737			45,737
Balance at Mar. 31, 2021	$ 699,359	$ 315,206	$ 7,012	$ 1,021,577

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Dividends and dividend equivalents declared per share (in dollars per share)	$ 0.60	$ 0.50

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 45,413	$ 35,756
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,529	4,328
Amortization of premium on available-for-sale securities	813	494
(Gain) loss on deferred compensation plan investments	(1,177)	3,750
Deferred taxes, net	1,004	3,412
Stock-based compensation expense	28,583	18,562
Other	5	(1)
Changes in operating assets and liabilities:
Accounts receivable	(17,236)	(1,635)
Inventories	(18,151)	(3,994)
Other assets	(2,215)	(10,061)
Accounts payable	13,513	7,185
Accrued compensation and related benefits	10,609	(7,374)
Income tax liabilities	1,800	34
Other accrued liabilities	8,567	963
Net cash provided by operating activities	77,057	51,419
Cash flows from investing activities:
Purchases of property and equipment	(18,970)	(9,951)
Purchases of short-term investments	(201,517)	(101,566)
Proceeds from maturities and sales of short-term investments	38,472	47,397
Proceeds from sales of long-term investments	25	100
Contributions to deferred compensation plan, net	(876)	(438)
Net cash used in investing activities	(182,866)	(64,458)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(563)	(279)
Proceeds from common stock issued under the employee equity incentive plan	10,744	11,758
Proceeds from common stock issued under the employee stock purchase plan	2,293	1,892
Dividends and dividend equivalents paid	(23,467)	(17,427)
Net cash used in financing activities	(10,993)	(4,056)
Effect of change in exchange rates	218	(985)
Net decrease in cash, cash equivalents and restricted cash	(116,584)	(18,080)
Cash, cash equivalents and restricted cash, beginning of period	335,071	173,076
Cash, cash equivalents and restricted cash, end of period	218,487	154,996
Supplemental disclosures for cash flow information:
Cash paid for taxes	377	279
Non-cash investing and financing activities:
Liability accrued for property and equipment purchases	12,963	10,909
Liability accrued for dividends and dividend equivalents	$ 29,000	$ 23,725

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Significant Accounting Policies [Text Block]	1. The accompanying unaudited condensed consolidated financial statements have been prepared by Monolithic Power Systems, Inc. (the “Company” or “MPS”) in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been condensed or omitted in accordance with these accounting principles, rules and regulations. The information in this report should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Annual Report on Form 10 December 31, 2020, March 1, 2021. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the Company’s financial position, results of operations and cash flows for the interim periods presented. The financial statements contained in this Quarterly Report on Form 10 not may December 31, 2021 Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions used in these condensed consolidated financial statements primarily include those related to revenue recognition, inventory valuation, valuation of share-based awards, contingencies and income tax valuation allowances. Actual results could differ from these estimates and assumptions, and any such differences may The COVID- 19 not three March 31, 2021 , As of the date of issuance of these condensed consolidated financial statements, the Company is not 19 10 December 31, 2020 . Recently Adopted Accounting Pronouncement In December 2019, No. 2019 12, Income Taxes (Topic 740 December 15, 2020. first 2021 not

Note 2 - Revenue Recognition

Note 2 - Revenue Recognition	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Revenue from Contract with Customer [Text Block]	2. REVENUE RECOGNITION Revenue from Product Sales The Company generates revenue primarily from product sales, which include assembled and tested integrated circuits (“ICs”), as well as dies in wafer form. These product sales accounted for 97% and 98% of the Company’s total revenue for the three March 31, 2021 2020 , third not 7 The Company sells its products primarily through third three March 31, 2021 2020, not The Company recognizes revenue when it satisfies a performance obligation by transferring control of the promised goods or services to its customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. The Company excludes taxes assessed by government authorities, such as sales taxes, from revenue. Product sales consist of a single performance obligation that the Company satisfies at a point in time. The Company recognizes product revenue from distributors and direct end customers when the following events have occurred: (a) the Company has transferred physical possession of the products, (b) the Company has a present right to payment, (c) the customer has legal title to the products, and (d) the customer bears significant risks and rewards of ownership of the products. In accordance with the shipping terms specified in the contracts, these criteria are generally met when the products are shipped from the Company’s facilities (such as the “Ex Works” shipping term) or delivered to the customers’ locations (such as the “Delivered Duty Paid” shipping term). Under certain consignment agreements, revenue is not not Variable Consideration The Company accounts for price adjustment and stock rotation rights as variable consideration that reduces the transaction price and recognizes that reduction in the same period the associated revenue is recognized. Four U.S.-based distributors have price adjustment rights when they sell the Company’s products to their end customers at a price that is lower than the distribution price invoiced by the Company. When the Company receives claims from the distributors that products have been sold to the end customers at the lower price, the Company issues the distributors credit memos for the price adjustments. The Company estimates the price adjustments using the expected value method based on an analysis of historical claims, at both the distributor and product level, as well as an assessment of any known trends of product sales mix. Other U.S. distributors and non-U.S. distributors, which make up the majority of the Company’s total sales to distributors, do not Certain distributors have limited stock rotation rights that permit the return of a small percentage of the previous six Contract Balances Accounts Receivable: The Company records a receivable when it has an unconditional right to receive consideration after the performance obligations are satisfied. As of March 31, 2021 December 31, 2020 , 30 90 not may not March 31, 2021 December 31, 2020 , not Contract Liabilities: For certain customers located in Asia, the Company requires cash payments two March 31, 2021 December 31, 2020 , three March 31, 2021 three March 31, 2021 , December 31, 2020 . Practical Expedients The Company has elected the practical expedient to expense sales commissions as incurred because the amortization period would have been one The Company’s standard payment terms generally require customers to pay 30 to 90 days after the Company satisfies the performance obligations. For those customers who are required to pay in advance, the Company satisfies the performance obligations generally within a quarter. The Company has elected not The Company’s unsatisfied performance obligations primarily include products held in consignment arrangements and customer purchase orders for products that the Company has not one not

Note 3 - Stock-based Compensati

Note 3 - Stock-based Compensation	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	3. 2014 In April 2013 , 2014 “2014 June 2013 . October 2014 , 2014 2014 November 13, 2014 April 2020 , 2014 2014 June 2020 . 2014 June 11, 2020 2014 June 11, 2030 . March 31, 2021 , 2014 Stock-Based Compensation Expense The Company recognized stock-based compensation expenses as follows (in thousands): Three Months Ended March 31, 2021 2020 Cost of revenue $ 816 $ 557 Research and development 6,165 4,370 Selling, general and administrative 21,602 13,635 Total stock-based compensation expense $ 28,583 $ 18,562 Tax benefit related to stock-based compensation (1) $ 430 $ 470 ( 1 Amount reflects the tax benefit related to stock-based compensation recorded for equity awards that are expected to generate tax deductions when they vest in future periods. Restricted Stock Units ( “ RSUs ” ) The Company’s RSUs include time-based RSUs, RSUs with performance conditions (“PSUs”), RSUs with market conditions (“MSUs”), and RSUs with both market and performance conditions (“MPSUs”). Vesting of awards with performance conditions or market conditions is subject to the achievement of pre-determined performance goals and the approval of such achievement by the Compensation Committee of the Board of Directors (the “Compensation Committee”). All awards include service conditions which require continued employment with the Company. A summary of RSU activity is presented in the table below (in thousands, except per-share amounts): Time-Based RSUs PSUs and MPSUs MSUs Total Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Outstanding at January 1, 2021 161 $ 151.62 1,390 $ 132.60 1,554 $ 40.40 3,105 $ 87.42 Granted 25 $ 374.57 362 (1) $ 351.85 - $ - 387 $ 353.33 Vested (21 ) $ 139.43 (358 ) $ 92.39 (81 ) $ 23.57 (460 ) $ 82.43 Forfeited (1 ) $ 163.87 (10 ) $ 86.01 (1 ) $ 68.48 (12 ) $ 94.88 Outstanding at March 31, 2021 164 $ 187.34 1,384 $ 200.75 1,472 $ 41.31 3,020 $ 122.26 ( 1 Amount reflects the number of awards that may The intrinsic value related to vested RSUs was $159.3 million and $182.1 million for the three March 31, 2021 2020, March 31, 2021, March 31, 2021, Cash proceeds from vested PSUs with a purchase price requirement totaled $10.7 million and $11.8 million for the three March 31, 2021 2020, Time-Based RSUs: For the three March 31, 2021, four one 2021 In February 2021 , two “2021 first 2021 two 2021 2022 two 2021 first 2023 2021 two second 100% 2021 December 31, 2023. 2021 no December 31, 2022. one 2021 In February 2021 , 2022 two 2021 2022 two “2021 2021 2021 first 2023 2021 two 2021 The 2021 2021 $30 20 December 31, 2022 $30 2021 2021 2021 2004 “ ESPP ” ) For the three March 31, 2021 2020, March 31, 2021, The intrinsic value of the shares issued was $1.4 million and $1.0 million for the three March 31, 2021 2020, March 31, 2021, third 2021. Three Months Ended March 31, 2021 2020 Expected term (in years) 0.5 0.5 Expected volatility 43.3 % 31.4 % Risk-free interest rate 0.1 % 1.6 % Dividend yield 0.6 % 1.1 % Cash proceeds from the shares issued under the ESPP were $2.3 million and $1.9 million for the three March 31, 2021 2020,

Note 4 - Balance Sheet Componen

Note 4 - Balance Sheet Components	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Supplemental Balance Sheet Disclosures [Text Block]	4. Inventories Inventories consist of the following (in thousands): March 31, December 31, 2021 2020 Raw materials $ 26,055 $ 25,503 Work in process 90,571 77,100 Finished goods 58,597 54,459 Total $ 175,223 $ 157,062 Other Current Assets Other current assets consist of the following (in thousands): March 31, December 31, 2021 2020 RSU tax withholding proceeds receivable $ 11,428 $ 12,504 Prepaid expense 7,225 5,032 Accrued interest receivable 2,126 1,914 Assets for product returns 1,724 1,684 Other 1,822 1,846 Total $ 24,325 $ 22,980 Other Long-Term Assets Other long-term assets consist of the following (in thousands): March 31, December 31, 2021 2020 Deferred compensation plan assets $ 48,138 $ 46,146 Operating lease right-of-use (“ROU”) assets 5,845 3,719 Prepaid expense 2,503 2,340 Debt investment 2,820 2,861 Equity investment in a privately held company 3,180 3,400 Other 1,296 1,372 Total $ 63,782 $ 59,838 Other Accrued Liabilities Other accrued liabilities consist of the following (in thousands): March 31, December 31, 2021 2020 Dividends and dividend equivalents $ 31,472 $ 26,435 Stock rotation and sales returns 6,240 6,005 Accrued purchases of property and equipment 5,339 5,841 Income tax payable 5,545 3,755 Customer prepayments 6,998 7,238 Commissions 1,252 1,107 Operating lease liabilities 1,953 1,406 Warranty 9,941 6,895 Other 5,627 4,278 Total $ 74,367 $ 62,960 Other Long-Term Liabilities Other long-term liabilities consist of the following (in thousands): March 31, December 31, 2021 2020 Deferred compensation plan liabilities $ 49,837 $ 48,280 Dividend equivalents 8,323 7,871 Operating lease liabilities 3,454 1,693 Other 30 29 Total $ 61,644 $ 57,873

Note 5 - Leases

Note 5 - Leases	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Leases Disclosure [Text Block]	5. Lessee The Company has operating leases primarily for administrative and sales and marketing offices, manufacturing operations and research and development facilities, employee housing units and certain equipment. These leases have remaining lease terms from less than a year to five two not As of March 31, 2021 December 31, 2020 , March 31, 2021 December 31, 2020 , Three Months Ended March 31, 2021 2020 Lease costs: Operating lease costs $ 499 $ 366 Other 121 77 Total lease costs $ 620 $ 443 Three Months Ended March 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 312 $ 373 ROU assets obtained in exchange for new operating lease liabilities $ 2,940 $ 277 March 31, December 31, 2021 2020 Weighted-average remaining lease term (in years) 3.6 2.7 Weighted-average discount rate 2.3 % 2.7 % As of March 31, 2021, 2021 (remaining nine months) $ 1,602 2022 1,582 2023 1,015 2024 829 2025 637 Thereafter 8 Total remaining lease payments 5,673 Less: imputed interest (266 ) Total lease liabilities $ 5,407 Reported as: Current liabilities $ 1,953 Long-term liabilities $ 3,454 As of March 31, 2021 , one not second 2021 five Lessor The Company owns certain office buildings and leases a portion of these properties to third one four five For the three March 31, 2021 2020, March 31, 2021, 2021 (remaining nine months) $ 1,691 2022 2,241 2023 1,568 2024 581 2025 59 Total $ 6,140

Note 6 - Net Income Per Share

Note 6 - Net Income Per Share	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Earnings Per Share [Text Block]	6. Basic net income per share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that would occur if outstanding securities or other contracts to issue common stock were exercised or converted into common shares, and calculated using the treasury stock method. Contingently issuable shares, including equity awards with performance conditions or market conditions, are considered outstanding common shares and included in the basic net income per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in the diluted net income per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period. The Company’s RSUs contain forfeitable rights to receive cash dividend equivalents, which are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not not not The following table sets forth the computation of basic and diluted net income per share (in thousands, except per-share amounts): Three Months Ended March 31, 2021 2020 Numerator: Net income $ 45,413 $ 35,756 Denominator: Weighted-average outstanding shares - basic 45,498 44,455 Effect of dilutive securities 2,213 2,215 Weighted-average outstanding shares - diluted 47,711 46,670 Net income per share: Basic $ 1.00 $ 0.80 Diluted $ 0.95 $ 0.77 Anti-dilutive common stock equivalents were not

Note 7 - Segment, Significant C

Note 7 - Segment, Significant Customers and Geographic Information	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	7. The Company operates in one The Company sells its products primarily through third 10% Three Months Ended March 31, Customer 2021 2020 Distributor A 26 % 23 % Distributor B 16 % * Direct customer A * 10 % * Represents less than 10%. The Company’s agreements with these third may may not The following table summarizes those customers with accounts receivable equal to 10% March 31, December 31, Customer 2021 2020 Distributor A 25 % 24 % Distributor B 18 % 21 % Value-added reseller A 11 % 13 % Direct customer A * 10 % * Represents less than 10%. The following is a summary of revenue by geographic regions (in thousands): Three Months Ended March 31, Country or Region 2021 2020 China $ 153,383 $ 105,737 Taiwan 30,445 16,540 Europe 20,380 13,072 South Korea 19,287 10,944 Southeast Asia 11,497 8,780 Japan 12,049 6,890 United States 7,302 3,737 Other 112 78 Total $ 254,455 $ 165,778 The following is a summary of revenue by product family (in thousands): Three Months Ended March 31, Product Family 2021 2020 DC to DC $ 241,429 $ 156,875 Lighting Control 13,026 8,903 Total $ 254,455 $ 165,778 The following is a summary of long-lived assets by geographic regions (in thousands): March 31, December 31, Country 2021 2020 China $ 167,625 $ 151,752 United States 101,891 101,768 Taiwan 18,435 18,797 Other 9,790 9,211 Total $ 297,741 $ 281,528

Note 8 - Commitments and Contin

Note 8 - Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	8. Product Warranties The Company generally provides one two no not The changes in warranty reserves are as follows (in thousands): Three Months Ended March 31, 2021 2020 Balance at beginning of period $ 6,895 $ 1,139 Warranty provision for product sales 3,609 541 Settlements made (313 ) (111 ) Unused warranty provision (250 ) (425 ) Balance at end of period $ 9,941 $ 1,144 Purchase Commitments The Company has outstanding purchase commitments with its suppliers and other parties that require the future purchases of goods or services, which primarily consist of wafer and other inventory purchases, assembly and other manufacturing services, construction or purchases of property and equipment, and license arrangements. As of March 31, 2021 , Litigation The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation initiated by its stockholders, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. These proceedings often involve complex questions of fact and law and may March 31, 2021 , no

Note 9 - Cash Equivalents, Inve

Note 9 - Cash Equivalents, Investments and Restricted Cash	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Financial Instruments Disclosure [Text Block]	9. The following is a summary of the Company’s cash, cash equivalents and debt investments (in thousands): March 31, December 31, 2021 2020 Cash $ 197,744 $ 300,609 Money market funds 20,624 34,335 Certificates of deposit 106,763 - Corporate debt securities 306,201 249,671 Commercial paper - 2,999 U.S. treasuries and government agency bonds 7,491 7,499 Auction-rate securities backed by student-loan notes 2,820 2,861 Total $ 641,643 $ 597,974 March 31, December 31, 2021 2020 Reported as: Cash and cash equivalents 218,368 334,944 Short-term investments 420,455 260,169 Debt investment within other long-term assets 2,820 2,861 Total $ 641,643 $ 597,974 The following table summarizes the contractual maturities of the short-term and long-term available-for-sale investments as of March 31, 2021 ( Amortized Cost Fair Value Due in less than 1 year $ 89,085 $ 89,289 Due in 1 - 5 years 330,053 331,166 Due in greater than 5 years 2,995 2,820 Total $ 422,133 $ 423,275 Gross realized gains and losses recognized on the sales of available-for-sale investments were not The following tables summarize the unrealized gain and loss positions related to the available-for sale investments (in thousands): March 31, 2021 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds $ 20,624 $ - $ - $ 20,624 Certificates of deposit 106,763 - - 106,763 Corporate debt securities 304,876 1,611 (286 ) 306,201 U.S. treasuries and government agency bonds 7,499 - (8 ) 7,491 Auction-rate securities backed by student-loan notes 2,995 - (175 ) 2,820 Total $ 442,757 $ 1,611 $ (469 ) $ 443,899 December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds $ 34,335 $ - $ - $ 34,335 Corporate debt securities 247,591 2,177 (97 ) 249,671 Commercial paper 2,999 - - 2,999 U.S. treasuries and government agency bonds 7,499 2 (2 ) 7,499 Auction-rate securities backed by student-loan notes 3,020 - (159 ) 2,861 Total $ 295,444 $ 2,179 $ (258 ) $ 297,365 The following tables present information about the available-for-sale investments that had been in a continuous unrealized loss position for less than 12 12 March 31, 2021 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 152,871 $ (286 ) $ - $ - $ 152,871 $ (286 ) U.S. treasuries and government agency bonds 7,491 (8 ) - - 7,491 (8 ) Auction-rate securities backed by student-loan notes - - 2,820 (175 ) 2,820 (175 ) Total $ 160,362 $ (294 ) $ 2,820 $ (175 ) $ 163,182 $ (469 ) December 31, 2020 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 59,144 $ (97 ) $ - $ - $ 59,144 $ (97 ) U.S. treasuries and government agency bonds 5,998 (2 ) - - 5,998 (2 ) Auction-rate securities backed by student-loan notes - - 2,861 (159 ) 2,861 (159 ) Total $ 65,142 $ (99 ) $ 2,861 $ (159 ) $ 68,003 $ (258 ) An impairment exists when the fair value of an investment is less than its amortized cost basis. As of March 31, 2021 December 31, 2020 , not one not The Company’s auction-rate securities are backed by pools of student loans supported by guarantees by the U.S. Department of Education. The underlying maturities of these securities are up to 25 not not not Non-Marketable Equity Investment In November 2020 , March 31, 2021 December 31, 2020 , not three March 31, 2021 . Restricted Cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported on the Condensed Consolidated Balance Sheets to the amounts reported on the Condensed Consolidated Statements of Cash Flows (in thousands): March 31, December 31, 2021 2020 Cash and cash equivalents $ 218,368 $ 334,944 Restricted cash included in other long-term assets 119 127 Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows $ 218,487 $ 335,071 As of March 31, 2021 December 31, 2020 ,

Note 10 - Fair Value Measuremen

Note 10 - Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Fair Value Disclosures [Text Block]	10. The following tables summarize the fair value of the financial assets measured on a recurring basis (in thousands): March 31, 2021 Total Level 1 Level 2 Level 3 Money market funds $ 20,624 $ 20,624 $ - $ - Certificates of deposit 106,763 - 106,763 - Corporate debt securities 306,201 - 306,201 - U.S. treasuries and government agency bonds 7,491 - 7,491 - Auction-rate securities backed by student-loan notes 2,820 - - 2,820 Mutual funds and money market funds under deferred compensation plan 28,252 28,252 - - Total $ 472,151 $ 48,876 $ 420,455 $ 2,820 December 31, 2020 Total Level 1 Level 2 Level 3 Money market funds $ 34,335 $ 34,335 $ - $ - Corporate debt securities 249,671 - 249,671 - Commercial paper 2,999 - 2,999 - U.S. treasuries and government agency bonds 7,499 - 7,499 - Auction-rate securities backed by student-loan notes 2,861 - - 2,861 Mutual funds and money market funds under deferred compensation plan 26,924 26,924 - - Total $ 324,289 $ 61,259 $ 260,169 $ 2,861 ● Level 1 ● Level 2 may third ● Level 3 Redemptions and changes in the fair value of the auction-rate securities classified as Level 3 not three March 31, 2021.

Note 11 - Deferred Compensation

Note 11 - Deferred Compensation Plan	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Compensation and Employee Benefit Plans [Text Block]	11. The following table summarizes the deferred compensation plan balances on the Condensed Consolidated Balance Sheets (in thousands): March 31, December 31, 2021 2020 Deferred compensation plan asset components: Cash surrender value of corporate-owned life insurance policies $ 19,886 $ 19,222 Fair value of mutual funds and money market funds 28,252 26,924 Total $ 48,138 $ 46,146 Deferred compensation plan assets reported in: Other long-term assets $ 48,138 $ 46,146 Deferred compensation plan liabilities reported in: Accrued compensation and related benefits (short-term) $ 396 $ 155 Other long-term liabilities 49,837 48,280 Total $ 50,233 $ 48,435

Note 12 - Other Income (Expense

Note 12 - Other Income (Expense), Net	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Other Nonoperating Income and Expense [Text Block]	12. The components of other income (expense), net, are as follows (in thousands): Three Months Ended March 31, 2021 2020 Interest income $ 2,282 $ 2,374 Amortization of premium on available-for-sale securities (813 ) (494 ) Gain (loss) on deferred compensation plan investments 1,177 (3,750 ) Foreign currency exchange gain 15 3 Other (74 ) 153 Total $ 2,587 $ (1,714 )

Note 13 - Income Taxes

Note 13 - Income Taxes	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Income Tax Disclosure [Text Block]	13. The income tax provision or benefit for interim periods is generally determined using an estimate of the Company’s annual effective tax rate and adjusted for discrete items, if any, in the relevant period. Each quarter the estimate of the annual effective tax rate is updated, and if the Company’s estimated tax rate changes, a cumulative adjustment is made. The income tax expense for the three March 31, 2021 The income tax benefit for the three March 31, 2020 The Company’s uncertain tax positions relate to the allocation of income and deductions among its global entities and to the determination of the research and development tax credit. Various events, some of which cannot be predicted, such as clarification of tax law by administrative or judicial means, may twelve not

Note 14 - Accumulated Other Com

Note 14 - Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Comprehensive Income (Loss) Note [Text Block]	14. INCOME The following table summarizes the changes in accumulated other comprehensive income (in thousands): Unrealized Gains on Available-for- Sale Securities Foreign Currency Translation Adjustments Total Balance as of January 1, 2021 $ 1,601 $ 8,539 $ 10,140 Other comprehensive loss before reclassifications (754 ) (2,474 ) (3,228 ) Amounts reclassified from accumulated other comprehensive income (24 ) - (24 ) Tax effect 124 - 124 Net current period other comprehensive loss (654 ) (2,474 ) (3,128 ) Balance as of March 31, 2021 $ 947 $ 6,065 $ 7,012 The amounts reclassified from accumulated other comprehensive income were recorded in other income (expense), net, on the Condensed Consolidated Statements of Operations.

Note 15 - Dividends and Dividen

Note 15 - Dividends and Dividend Equivalents	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Dividends And Dividend Equivalents [Text Block]	15. Cash Dividend Program The Company has a dividend program approved by the Board of Directors, pursuant to which the Company intends to pay quarterly cash dividends on its common stock. Based on the Company’s historical practice, stockholders of record as of the last business day of the quarter are entitled to receive the quarterly cash dividends when and if declared by the Board of Directors, which are payable to the stockholders in the following month. The Board of Directors declared the following cash dividends (in thousands, except per-share amounts): Three Months Ended March 31, 2021 2020 Dividend declared per share $ 0.60 $ 0.50 Total amount $ 27,393 $ 22,317 As of March 31, 2021 December 31, 2020, The declaration of any future cash dividends is at the discretion of the Board of Directors and will depend on, among other things, the Company’s financial condition, results of operations, capital requirements, business conditions, and other factors that the Board of Directors may The Company anticipates that cash used for future dividend payments will come from its domestic cash, cash generated from ongoing U.S. operations, and cash repatriated from its Bermuda subsidiary. The Company also anticipates that earnings from other foreign subsidiaries will continue to be indefinitely reinvested. Cash Dividend Equivalent Rights The Company's RSUs contain rights to receive cash dividend equivalents, which entitle employees who hold RSUs to the same dividend value per share as holders of common stock. The dividend equivalents are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not not March 31, 2021 December 31, 2020 ,

Significant Accounting Policies

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions used in these condensed consolidated financial statements primarily include those related to revenue recognition, inventory valuation, valuation of share-based awards, contingencies and income tax valuation allowances. Actual results could differ from these estimates and assumptions, and any such differences may The COVID- 19 not three March 31, 2021 , As of the date of issuance of these condensed consolidated financial statements, the Company is not 19 10 December 31, 2020 .
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Adopted Accounting Pronouncement In December 2019, No. 2019 12, Income Taxes (Topic 740 December 15, 2020. first 2021 not

Note 3 - Stock-based Compensa_2

Note 3 - Stock-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Share-based Payment Arrangement, Cost by Plan [Table Text Block]	Three Months Ended March 31, 2021 2020 Cost of revenue $ 816 $ 557 Research and development 6,165 4,370 Selling, general and administrative 21,602 13,635 Total stock-based compensation expense $ 28,583 $ 18,562 Tax benefit related to stock-based compensation (1) $ 430 $ 470
Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]	Time-Based RSUs PSUs and MPSUs MSUs Total Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Number of Shares Weighted- Average Grant Date Fair Value Per Share Outstanding at January 1, 2021 161 $ 151.62 1,390 $ 132.60 1,554 $ 40.40 3,105 $ 87.42 Granted 25 $ 374.57 362 (1) $ 351.85 - $ - 387 $ 353.33 Vested (21 ) $ 139.43 (358 ) $ 92.39 (81 ) $ 23.57 (460 ) $ 82.43 Forfeited (1 ) $ 163.87 (10 ) $ 86.01 (1 ) $ 68.48 (12 ) $ 94.88 Outstanding at March 31, 2021 164 $ 187.34 1,384 $ 200.75 1,472 $ 41.31 3,020 $ 122.26
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]	Three Months Ended March 31, 2021 2020 Expected term (in years) 0.5 0.5 Expected volatility 43.3 % 31.4 % Risk-free interest rate 0.1 % 1.6 % Dividend yield 0.6 % 1.1 %

Note 4 - Balance Sheet Compon_2

Note 4 - Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Inventory, Current [Table Text Block]	March 31, December 31, 2021 2020 Raw materials $ 26,055 $ 25,503 Work in process 90,571 77,100 Finished goods 58,597 54,459 Total $ 175,223 $ 157,062
Schedule of Other Current Assets [Table Text Block]	March 31, December 31, 2021 2020 RSU tax withholding proceeds receivable $ 11,428 $ 12,504 Prepaid expense 7,225 5,032 Accrued interest receivable 2,126 1,914 Assets for product returns 1,724 1,684 Other 1,822 1,846 Total $ 24,325 $ 22,980
Schedule of Other Assets, Noncurrent [Table Text Block]	March 31, December 31, 2021 2020 Deferred compensation plan assets $ 48,138 $ 46,146 Operating lease right-of-use (“ROU”) assets 5,845 3,719 Prepaid expense 2,503 2,340 Debt investment 2,820 2,861 Equity investment in a privately held company 3,180 3,400 Other 1,296 1,372 Total $ 63,782 $ 59,838
Schedule of Accrued Liabilities [Table Text Block]	March 31, December 31, 2021 2020 Dividends and dividend equivalents $ 31,472 $ 26,435 Stock rotation and sales returns 6,240 6,005 Accrued purchases of property and equipment 5,339 5,841 Income tax payable 5,545 3,755 Customer prepayments 6,998 7,238 Commissions 1,252 1,107 Operating lease liabilities 1,953 1,406 Warranty 9,941 6,895 Other 5,627 4,278 Total $ 74,367 $ 62,960
Other Noncurrent Liabilities [Table Text Block]	March 31, December 31, 2021 2020 Deferred compensation plan liabilities $ 49,837 $ 48,280 Dividend equivalents 8,323 7,871 Operating lease liabilities 3,454 1,693 Other 30 29 Total $ 61,644 $ 57,873

Note 5 - Leases (Tables)

Note 5 - Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Lease, Cost [Table Text Block]	Three Months Ended March 31, 2021 2020 Lease costs: Operating lease costs $ 499 $ 366 Other 121 77 Total lease costs $ 620 $ 443 Three Months Ended March 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 312 $ 373 ROU assets obtained in exchange for new operating lease liabilities $ 2,940 $ 277 March 31, December 31, 2021 2020 Weighted-average remaining lease term (in years) 3.6 2.7 Weighted-average discount rate 2.3 % 2.7 %
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	2021 (remaining nine months) $ 1,602 2022 1,582 2023 1,015 2024 829 2025 637 Thereafter 8 Total remaining lease payments 5,673 Less: imputed interest (266 ) Total lease liabilities $ 5,407 Reported as: Current liabilities $ 1,953 Long-term liabilities $ 3,454
Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Table Text Block]	2021 (remaining nine months) $ 1,691 2022 2,241 2023 1,568 2024 581 2025 59 Total $ 6,140

Note 6 - Net Income Per Share (

Note 6 - Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended March 31, 2021 2020 Numerator: Net income $ 45,413 $ 35,756 Denominator: Weighted-average outstanding shares - basic 45,498 44,455 Effect of dilutive securities 2,213 2,215 Weighted-average outstanding shares - diluted 47,711 46,670 Net income per share: Basic $ 1.00 $ 0.80 Diluted $ 0.95 $ 0.77

Note 7 - Segment, Significant_2

Note 7 - Segment, Significant Customers and Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]	Three Months Ended March 31, Customer 2021 2020 Distributor A 26 % 23 % Distributor B 16 % * Direct customer A * 10 % March 31, December 31, Customer 2021 2020 Distributor A 25 % 24 % Distributor B 18 % 21 % Value-added reseller A 11 % 13 % Direct customer A * 10 %
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	Three Months Ended March 31, Country or Region 2021 2020 China $ 153,383 $ 105,737 Taiwan 30,445 16,540 Europe 20,380 13,072 South Korea 19,287 10,944 Southeast Asia 11,497 8,780 Japan 12,049 6,890 United States 7,302 3,737 Other 112 78 Total $ 254,455 $ 165,778
Revenue from External Customers by Products and Services [Table Text Block]	Three Months Ended March 31, Product Family 2021 2020 DC to DC $ 241,429 $ 156,875 Lighting Control 13,026 8,903 Total $ 254,455 $ 165,778
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]	March 31, December 31, Country 2021 2020 China $ 167,625 $ 151,752 United States 101,891 101,768 Taiwan 18,435 18,797 Other 9,790 9,211 Total $ 297,741 $ 281,528

Note 8 - Commitments and Cont_2

Note 8 - Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Product Warranty Liability [Table Text Block]	Three Months Ended March 31, 2021 2020 Balance at beginning of period $ 6,895 $ 1,139 Warranty provision for product sales 3,609 541 Settlements made (313 ) (111 ) Unused warranty provision (250 ) (425 ) Balance at end of period $ 9,941 $ 1,144

Note 9 - Cash Equivalents, In_2

Note 9 - Cash Equivalents, Investments and Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Fair Value, by Balance Sheet Grouping [Table Text Block]	March 31, December 31, 2021 2020 Cash $ 197,744 $ 300,609 Money market funds 20,624 34,335 Certificates of deposit 106,763 - Corporate debt securities 306,201 249,671 Commercial paper - 2,999 U.S. treasuries and government agency bonds 7,491 7,499 Auction-rate securities backed by student-loan notes 2,820 2,861 Total $ 641,643 $ 597,974 March 31, December 31, 2021 2020 Reported as: Cash and cash equivalents 218,368 334,944 Short-term investments 420,455 260,169 Debt investment within other long-term assets 2,820 2,861 Total $ 641,643 $ 597,974
Investments Classified by Contractual Maturity Date [Table Text Block]	Amortized Cost Fair Value Due in less than 1 year $ 89,085 $ 89,289 Due in 1 - 5 years 330,053 331,166 Due in greater than 5 years 2,995 2,820 Total $ 422,133 $ 423,275
Unrealized Gain (Loss) on Investments [Table Text Block]	March 31, 2021 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds $ 20,624 $ - $ - $ 20,624 Certificates of deposit 106,763 - - 106,763 Corporate debt securities 304,876 1,611 (286 ) 306,201 U.S. treasuries and government agency bonds 7,499 - (8 ) 7,491 Auction-rate securities backed by student-loan notes 2,995 - (175 ) 2,820 Total $ 442,757 $ 1,611 $ (469 ) $ 443,899 December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds $ 34,335 $ - $ - $ 34,335 Corporate debt securities 247,591 2,177 (97 ) 249,671 Commercial paper 2,999 - - 2,999 U.S. treasuries and government agency bonds 7,499 2 (2 ) 7,499 Auction-rate securities backed by student-loan notes 3,020 - (159 ) 2,861 Total $ 295,444 $ 2,179 $ (258 ) $ 297,365
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block]	March 31, 2021 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 152,871 $ (286 ) $ - $ - $ 152,871 $ (286 ) U.S. treasuries and government agency bonds 7,491 (8 ) - - 7,491 (8 ) Auction-rate securities backed by student-loan notes - - 2,820 (175 ) 2,820 (175 ) Total $ 160,362 $ (294 ) $ 2,820 $ (175 ) $ 163,182 $ (469 ) December 31, 2020 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 59,144 $ (97 ) $ - $ - $ 59,144 $ (97 ) U.S. treasuries and government agency bonds 5,998 (2 ) - - 5,998 (2 ) Auction-rate securities backed by student-loan notes - - 2,861 (159 ) 2,861 (159 ) Total $ 65,142 $ (99 ) $ 2,861 $ (159 ) $ 68,003 $ (258 )
Restrictions on Cash and Cash Equivalents [Table Text Block]	March 31, December 31, 2021 2020 Cash and cash equivalents $ 218,368 $ 334,944 Restricted cash included in other long-term assets 119 127 Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows $ 218,487 $ 335,071

Note 10 - Fair Value Measurem_2

Note 10 - Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	March 31, 2021 Total Level 1 Level 2 Level 3 Money market funds $ 20,624 $ 20,624 $ - $ - Certificates of deposit 106,763 - 106,763 - Corporate debt securities 306,201 - 306,201 - U.S. treasuries and government agency bonds 7,491 - 7,491 - Auction-rate securities backed by student-loan notes 2,820 - - 2,820 Mutual funds and money market funds under deferred compensation plan 28,252 28,252 - - Total $ 472,151 $ 48,876 $ 420,455 $ 2,820 December 31, 2020 Total Level 1 Level 2 Level 3 Money market funds $ 34,335 $ 34,335 $ - $ - Corporate debt securities 249,671 - 249,671 - Commercial paper 2,999 - 2,999 - U.S. treasuries and government agency bonds 7,499 - 7,499 - Auction-rate securities backed by student-loan notes 2,861 - - 2,861 Mutual funds and money market funds under deferred compensation plan 26,924 26,924 - - Total $ 324,289 $ 61,259 $ 260,169 $ 2,861

Note 11 - Deferred Compensati_2

Note 11 - Deferred Compensation Plan (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits by Title of Individual and Type of Deferred Compensation [Table Text Block]	March 31, December 31, 2021 2020 Deferred compensation plan asset components: Cash surrender value of corporate-owned life insurance policies $ 19,886 $ 19,222 Fair value of mutual funds and money market funds 28,252 26,924 Total $ 48,138 $ 46,146 Deferred compensation plan assets reported in: Other long-term assets $ 48,138 $ 46,146 Deferred compensation plan liabilities reported in: Accrued compensation and related benefits (short-term) $ 396 $ 155 Other long-term liabilities 49,837 48,280 Total $ 50,233 $ 48,435

Note 12 - Other Income (Expen_2

Note 12 - Other Income (Expense), Net (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Other Nonoperating Income (Expense) [Table Text Block]	Three Months Ended March 31, 2021 2020 Interest income $ 2,282 $ 2,374 Amortization of premium on available-for-sale securities (813 ) (494 ) Gain (loss) on deferred compensation plan investments 1,177 (3,750 ) Foreign currency exchange gain 15 3 Other (74 ) 153 Total $ 2,587 $ (1,714 )

Note 14 - Accumulated Other C_2

Note 14 - Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Unrealized Gains on Available-for- Sale Securities Foreign Currency Translation Adjustments Total Balance as of January 1, 2021 $ 1,601 $ 8,539 $ 10,140 Other comprehensive loss before reclassifications (754 ) (2,474 ) (3,228 ) Amounts reclassified from accumulated other comprehensive income (24 ) - (24 ) Tax effect 124 - 124 Net current period other comprehensive loss (654 ) (2,474 ) (3,128 ) Balance as of March 31, 2021 $ 947 $ 6,065 $ 7,012

Note 15 - Dividends and Divid_2

Note 15 - Dividends and Dividend Equivalents (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Dividends Declared [Table Text Block]	Three Months Ended March 31, 2021 2020 Dividend declared per share $ 0.60 $ 0.50 Total amount $ 27,393 $ 22,317

Note 2 - Revenue Recognition (D

Note 2 - Revenue Recognition (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Lapse Period for Consignment (Day)	60 days
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 84,059		$ 66,843
Accounts Receivable, Allowance for Credit Loss, Ending Balance	0		0
Contract with Customer, Liability, Current	6,998		7,238
Contract with Customer, Liability, Revenue Recognized	$ 6,700
Minimum [Member]
Contract with Customer, Payment Term (Day)	30 days
Maximum [Member]
Contract with Customer, Payment Term (Day)	90 years
Certain Customers in China [Member]
Contract with Customer, Payment Term Required Prior to Shipping Products (Week)	14 days
Certain Customers in China [Member] | Accrued Liabilities, Current [Member]
Contract with Customer, Liability, Current	$ 7,000		$ 7,200
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	89.00%	80.00%
Product [Member]
Percentage of Revenue	97.00%	98.00%

Note 3 - Stock-based Compensa_3

Note 3 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Jun. 11, 2020	Feb. 28, 2021	Mar. 31, 2021	Mar. 31, 2020	Nov. 13, 2014
Share Price (in dollars per share)		$ 374.57	$ 353.21
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised			$ 10,744	$ 11,758
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)			387,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)			$ 353.33
Proceeds from Stock Plans			$ 2,293	1,892
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested			159,300	182,100
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding			1,000,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			$ 243,900
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			2 years 1 month 6 days
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised			$ 10,700	$ 11,800
Time-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)			25,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)			$ 374.57
Time-Based RSUs [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)			4 years
Time-Based RSUs [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)			1 year
PSU 2021 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share)		30
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)		$ 374.57
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		41.40%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		0.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		0.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions		9.80%
PSU 2021 [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)		80,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed		300.00%
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)		2 years
Maximum Stock Compensation Costs		$ 114,400
PSU 2021 [Member] | Executive Officer [Member] | Vesting First Quarter of 2023 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
PSU 2021 [Member] | Executive Officer [Member] | Vesting Over Two Years Following First Quarter of 2023 on Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
PSU 2021 [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)		14,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)		2 years
Maximum Stock Compensation Costs		$ 12,500
PSU 2021 [Member] | Non-Executive Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed		200.00%
PSU 2021 [Member] | Non-Executive Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed		300.00%
PSU 2021 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2021 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
PSU 2021 [Member] | Non-Executive Employees [Member] | Vesting Over Two Years Following First Quarter of 2021 on an Annual or Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
The2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)					5,500,000
Amended and Restated 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)	10,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)			5,600,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)			4,500,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			$ 600
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)			10,000	15,000
Employee Stock Purchase Plan Shares Issued, Intrinsic Value			$ 1,400	$ 1,000
Proceeds from Stock Plans			$ 2,300	$ 1,900

Note 3 - Stock-based Compensa_4

Note 3 - Stock-based Compensation - Stock-based Compensation Plan Expenses (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Share based compensation expense		$ 28,583	$ 18,562
Tax benefit related to stock-based compensation	[1]	430	470
Cost of Sales [Member]
Share based compensation expense		816	557
Research and Development Expense [Member]
Share based compensation expense		6,165	4,370
Selling, General and Administrative Expenses [Member]
Share based compensation expense		$ 21,602	$ 13,635
[1]	Amount reflects the tax benefit related to stock-based compensation recorded for equity awards that are expected to generate tax deductions when they vest in future periods.

Note 3 - Stock-based Compensa_5

Note 3 - Stock-based Compensation - RSU Summary (Details)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Beginning balance (in shares) | shares	3,105,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 87.42
Granted (in shares) | shares	387,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 353.33
Vested (in shares) | shares	(460,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 82.43
Forfeited (in shares) | shares	(12,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 94.88
Ending balance (in shares) | shares	3,020,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 122.26
Time-Based RSUs [Member]
Beginning balance (in shares) | shares	161,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 151.62
Granted (in shares) | shares	25,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 374.57
Vested (in shares) | shares	(21,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 139.43
Forfeited (in shares) | shares	(1,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 163.87
Ending balance (in shares) | shares	164,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 187.34
PSUs and MPSUs [Member]
Beginning balance (in shares) | shares	1,390,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 132.60
Granted (in shares) | shares	362,000	[1]
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 351.85
Vested (in shares) | shares	(358,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 92.39
Forfeited (in shares) | shares	(10,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 86.01
Ending balance (in shares) | shares	1,384,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 200.75
MSUs [Member]
Beginning balance (in shares) | shares	1,554,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 40.40
Granted (in shares) | shares	0
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 0
Vested (in shares) | shares	(81,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 23.57
Forfeited (in shares) | shares	(1,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 68.48
Ending balance (in shares) | shares	1,472,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 41.31
[1]	Amount reflects the number of awards that may ultimately be earned based on management’s probability assessment of the achievement of performance conditions at each reporting period.

Note 3 - Stock-based Compensa_6

Note 3 - Stock-based Compensation - Valuation Assumptions (Details) - 2004 Employee Stock Plan [Member] - Employee Stock Purchase Plan [Member]	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Expected term (Year)	6 months	6 months
Expected volatility	43.30%	31.40%
Risk-free interest rate	0.10%	1.60%
Dividend yield	0.60%	1.10%

Note 4 - Balance Sheet Compon_3

Note 4 - Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Raw materials	$ 26,055	$ 25,503
Work in process	90,571	77,100
Finished goods	58,597	54,459
Total	$ 175,223	$ 157,062

Note 4 - Balance Sheet Compon_4

Note 4 - Balance Sheet Components - Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
RSU tax withholding proceeds receivable	$ 11,428	$ 12,504
Prepaid expense	7,225	5,032
Accrued interest receivable	2,126	1,914
Assets for product returns	1,724	1,684
Other	1,822	1,846
Total	$ 24,325	$ 22,980

Note 4 - Balance Sheet Compon_5

Note 4 - Balance Sheet Components - Other Long-term Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred compensation plan assets	$ 48,138	$ 46,146
Operating lease right-of-use (“ROU”) assets	5,845	3,719
Prepaid expense	2,503	2,340
Debt investment	2,820	2,861
Equity investment in a privately held company	3,180	3,400
Other	1,296	1,372
Total	$ 63,782	$ 59,838

Note 4 - Balance Sheet Compon_6

Note 4 - Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Dividends and dividend equivalents	$ 31,472	$ 26,435
Stock rotation and sales returns	6,240	6,005
Accrued purchases of property and equipment	5,339	5,841
Income tax payable	5,545	3,755
Customer prepayments	6,998	7,238
Commissions	1,252	1,107
Warranty	9,941	6,895
Other	5,627	4,278
Total	74,367	62,960
Accrued Liabilities, Current [Member]
Operating lease liabilities	$ 1,953	$ 1,406

Note 4 - Balance Sheet Compon_7

Note 4 - Balance Sheet Components - Other Long-term Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred compensation plan liabilities	$ 49,837	$ 48,280
Dividend equivalents	8,323	7,871
Other	30	29
Total	61,644	57,873
Other Long-term Liabilities [Member]
Operating lease liabilities	$ 3,454	$ 1,693

Note 5 - Leases (Details Textua

Note 5 - Leases (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Operating Lease, Right-of-Use Asset	$ 5,845		$ 3,719
Lessee, Operating Lease, Lease Not yet Commenced, Future Lease Obligations	$ 4,000
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract (Year)	5 years
Operating Lease, Lease Income, Lease Payments	$ 300	$ 400
Other Assets [Member]
Operating Lease, Right-of-Use Asset	5,800		3,700
Other Liabilities [Member]
Operating Lease, Liability, Total	$ 5,400		$ 3,100
Maximum [Member]
Lessee, Operating Lease, Renewal Term (Year)	2 years
Lessor, Operating Lease, Remaining Lease Term (Year)	4 years
Lessor, Operating Lease, Renewal Term (Year)	5 years
Minimum [Member]
Lessor, Operating Lease, Remaining Lease Term (Year)	1 year

Note 5 - Leases - Leases Cost (

Note 5 - Leases - Leases Cost (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Operating lease costs		$ 499	$ 366
Other		121	77
Total lease costs		620	443
Operating cash flows from operating leases		312	373
ROU assets obtained in exchange for new operating lease liabilities	[1]	$ 2,940	$ 277
Weighted-average remaining lease term (in years) (Year)		3 years 7 months 6 days		2 years 8 months 12 days
Weighted-average discount rate		2.30%		2.70%
[1]	For the year ended December 31, 2019, the amount includes $2.3 million for operating leases existing on January 1, 2019, the adoption date of ASU No. 2016-02, Leases (Topic 842).

Note 5 - Leases - Maturities of

Note 5 - Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
2021 (remaining nine months)	$ 1,602
2022	1,582
2023	1,015
2024	829
2025	637
Thereafter	8
Total remaining lease payments	5,673
Less: imputed interest	(266)
Accrued Liabilities and Other Long-term Liabilities [Member]
Total lease liabilities	5,407
Accrued Liabilities, Current [Member]
Current liabilities	1,953	$ 1,406
Other Long-term Liabilities [Member]
Long-term liabilities	$ 3,454	$ 1,693

Note 5 - Leases - Maturities _2

Note 5 - Leases - Maturities of Income Related to Lease Payments (Details) $ in Thousands	Mar. 31, 2021USD ($)
2021 (remaining nine months)	$ 1,691
2022	2,241
2023	1,568
2024	581
2025	59
Total	$ 6,140

Note 6 - Net Income Per Share -

Note 6 - Net Income Per Share - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income	$ 45,413	$ 35,756
Weighted-average outstanding shares - basic (in shares)	45,498	44,455
Effect of dilutive securities (in shares)	2,213	2,215
Weighted-average outstanding shares - diluted (in shares)	47,711	46,670
Earnings per share, basic (in dollars per share)	$ 1	$ 0.80
Earnings per share, diluted (in dollars per share)	$ 0.95	$ 0.77

Note 7 - Segment, Significant_3

Note 7 - Segment, Significant Customers and Geographic Information (Details Textual)	3 Months Ended
	Mar. 31, 2021
Number of Reportable Segments	1

Note 7 - Segment, Significant_4

Note 7 - Segment, Significant Customers and Geographic Information - Customers with Sales and Accounts Receivable Greater Than 10% (Details) - Customer Concentration Risk [Member]	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue Benchmark [Member]
Concentration risk	89.00%	80.00%
Revenue Benchmark [Member] | Distributor A [Member]
Concentration risk	26.00%	23.00%
Revenue Benchmark [Member] | Distributor B [Member]
Concentration risk	16.00%
Revenue Benchmark [Member] | Customer A (Direct) [Member]
Concentration risk		10.00%
Accounts Receivable [Member] | Distributor A [Member]
Concentration risk	25.00%		24.00%
Accounts Receivable [Member] | Distributor B [Member]
Concentration risk	18.00%		21.00%
Accounts Receivable [Member] | Value Added Reseller A [Member]
Concentration risk	11.00%		13.00%
Accounts Receivable [Member] | Customer A (Direct) [Member]
Concentration risk			10.00%

Note 7 - Segment, Significant_5

Note 7 - Segment, Significant Customers and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue	$ 254,455	$ 165,778
CHINA
Revenue	153,383	105,737
TAIWAN, PROVINCE OF CHINA
Revenue	30,445	16,540
Europe [Member]
Revenue	20,380	13,072
KOREA, REPUBLIC OF
Revenue	19,287	10,944
South East Asia [Member]
Revenue	11,497	8,780
JAPAN
Revenue	12,049	6,890
UNITED STATES
Revenue	7,302	3,737
Other Region [Member]
Revenue	$ 112	$ 78

Note 7 - Segment, Significant_6

Note 7 - Segment, Significant Customers and Geographic Information - Revenue by Product Family (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue	$ 254,455	$ 165,778
DC To DC Products [Member]
Revenue	241,429	156,875
Lighting Control Products [Member]
Revenue	$ 13,026	$ 8,903

Note 7 - Segment, Significant_7

Note 7 - Segment, Significant Customers and Geographic Information - Long Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Long lived assets by region	$ 297,741	$ 281,528
CHINA
Long lived assets by region	167,625	151,752
UNITED STATES
Long lived assets by region	101,891	101,768
TAIWAN, PROVINCE OF CHINA
Long lived assets by region	18,435	18,797
Other Region [Member]
Long lived assets by region	$ 9,790	$ 9,211

Note 8 - Commitments and Cont_3

Note 8 - Commitments and Contingencies (Details Textual) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Purchase Obligation, Total	$ 152.2
Minimum [Member]
Warranty Period (Year)	1 year
Maximum [Member]
Warranty Period (Year)	2 years

Note 8 - Commitments and Cont_4

Note 8 - Commitments and Contingencies - Changes in Warranty Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Balance	$ 6,895	$ 1,139
Warranty provision for product sales	3,609	541
Settlements made	(313)	(111)
Unused warranty provision	(250)	(425)
Balance	$ 9,941	$ 1,144

Note 9 - Cash Equivalents, In_3

Note 9 - Cash Equivalents, Investments and Restricted Cash (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Total	$ 0	$ 0
Redemption, Auction Rate Securities to Date	$ 40,300
Percentage of Auction Rate Securities Redeemed at Par Value	93.00%
Equity Securities without Readily Determinable Fair Value, Amount	$ 3,180		$ 3,400

Note 9 - Cash Equivalents, In_4

Note 9 - Cash Equivalents, Investments and Restricted Cash - Cash Equivalents, Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash	$ 197,744	$ 300,609
Money market funds	20,624	34,335
Certificates of deposit	106,763	0
Commercial paper	0	2,999
U.S. treasuries and government agency bonds	7,491	7,499
Total	641,643	597,974
Cash and cash equivalents	218,368	334,944
Short-term investments	420,455	260,169
Debt investment within other long-term assets	2,820	2,861
Corporate Debt Securities [Member]
Available-for-sale securities	306,201	249,671
Auction Rate Securities [Member]
Available-for-sale securities	$ 2,820	$ 2,861

Note 9 - Cash Equivalents, In_5

Note 9 - Cash Equivalents, Investments and Restricted Cash - Investment Maturity Classification (Details) $ in Thousands	Mar. 31, 2021USD ($)
Due in less than 1 year, Amortized cost	$ 89,085
Due in less than 1 year, fair value	89,289
Due in 1 - 5 years, Amortized cost	330,053
Due in 1 - 5 years	331,166
Due in greater than 5 years, Amortized cost	2,995
Due in greater than 5 years	2,820
Total, Amortized cost	422,133
Total	$ 423,275

Note 9 - Cash Equivalents, In_6

Note 9 - Cash Equivalents, Investments and Restricted Cash - Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost	$ 442,757	$ 295,444
Unrealized Gains	1,611	2,179
Unrealized Losses	(469)	(258)
Total Fair Value	443,899	297,365
Money Market Funds [Member]
Amortized Cost	20,624	34,335
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	20,624	34,335
Certificates of Deposit [Member]
Amortized Cost	106,763
Unrealized Gains	0
Unrealized Losses	0
Total Fair Value	106,763
Corporate Debt Securities [Member]
Amortized Cost	304,876	247,591
Unrealized Gains	1,611	2,177
Unrealized Losses	(286)	(97)
Total Fair Value	306,201	249,671
Commercial Paper [Member]
Amortized Cost		2,999
Unrealized Gains		0
Unrealized Losses		0
Total Fair Value		2,999
US Government Agencies Short-term Debt Securities [Member]
Amortized Cost	7,499	7,499
Unrealized Gains	0	2
Unrealized Losses	(8)	(2)
Total Fair Value	7,491	7,499
Auction Rate Securities [Member]
Amortized Cost	2,995	3,020
Unrealized Gains	0	0
Unrealized Losses	(175)	(159)
Total Fair Value	$ 2,820	$ 2,861

Note 9 - Cash Equivalents, In_7

Note 9 - Cash Equivalents, Investments and Restricted Cash - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Continuous Unrealized Loss Position, Less than 12 Months	$ 160,362	$ 65,142
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(294)	(99)
Continuous Unrealized Loss Position, 12 Months or Longer	2,820	2,861
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(175)	(159)
Unrealized Loss Position, Total	163,182	68,003
Unrealized Loss Position, Accumulated Loss, Total	(469)	(258)
Corporate Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	152,871	59,144
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(286)	(97)
Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Unrealized Loss Position, Total	152,871	59,144
Unrealized Loss Position, Accumulated Loss, Total	(286)	(97)
US Treasury and Government Short-term Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	7,491
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(8)
Continuous Unrealized Loss Position, 12 Months or Longer	0
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Unrealized Loss Position, Total	7,491
Unrealized Loss Position, Accumulated Loss, Total	(8)
US Government Agencies Short-term Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months		5,998
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(2)
Continuous Unrealized Loss Position, 12 Months or Longer		0
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Unrealized Loss Position, Total		5,998
Unrealized Loss Position, Accumulated Loss, Total		(2)
Auction Rate Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	0	0
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Continuous Unrealized Loss Position, 12 Months or Longer	2,820	2,861
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(175)	(159)
Unrealized Loss Position, Total	2,820	2,861
Unrealized Loss Position, Accumulated Loss, Total	$ (175)	$ (159)

Note 9 - Cash Equivalents, In_8

Note 9 - Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 218,368	$ 334,944
Restricted cash included in other long-term assets	119	127
Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows	$ 218,487	$ 335,071	$ 154,996	$ 173,076

Note 10 - Fair Value Measurem_3

Note 10 - Fair Value Measurements - Financial Assets and Liabilities, Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Total Fair Value	$ 443,899	$ 297,365
Assets, fair value	472,151	324,289
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	48,876	61,259
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	420,455	260,169
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	2,820	2,861
Money Market Funds [Member]
Total Fair Value	20,624	34,335
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	20,624	34,335
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Certificates of Deposit [Member]
Total Fair Value	106,763
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	106,763
Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0
Corporate Debt Securities [Member]
Total Fair Value	306,201	249,671
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	306,201	249,671
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Commercial Paper [Member]
Total Fair Value		2,999
Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value		0
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value		2,999
Commercial Paper [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value		0
US Government Agencies Short-term Debt Securities [Member]
Total Fair Value	7,491	7,499
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	7,491	7,499
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Auction Rate Securities [Member]
Total Fair Value	2,820	2,861
Auction Rate Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	2,820	2,861
Mutual Fund [Member]
Total Fair Value	28,252	26,924
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	28,252	26,924
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	$ 0	$ 0

Note 11 - Deferred Compensati_3

Note 11 - Deferred Compensation Plan - Summary of Deferred Compensation Plan (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred compensation plan assets	$ 48,138	$ 46,146
Deferred compensation plan liabilities	50,233	48,435
Other Long-term Assets [Member]
Deferred compensation plan assets	48,138	46,146
Accrued Compensation and Related Benefits [Member]
Deferred compensation plan liabilities	396	155
Other Long-term Liabilities [Member]
Deferred compensation plan liabilities	49,837	48,280
Cash Surrender Value [Member]
Deferred compensation plan assets	19,886	19,222
Mutual Funds and Money Market Funds, Fair Value [Member]
Deferred compensation plan assets	$ 28,252	$ 26,924

Note 12 - Other Income (Expen_3

Note 12 - Other Income (Expense), Net - Interest and Other Income Components (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest income	$ 2,282	$ 2,374
Amortization of premium on available-for-sale securities	(813)	(494)
Gain (loss) on deferred compensation plan investments	1,177	(3,750)
Foreign currency exchange gain	15	3
Other	(74)	153
Total	$ 2,587	$ (1,714)

Note 13 - Income Taxes (Details

Note 13 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Expense (Benefit), Total	$ 3,260	$ (6,484)
Effective Income Tax Rate Reconciliation, Percent, Total	6.70%	22.20%

Note 14 - Accumulated Other C_3

Note 14 - Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Balance	$ 966,587
Balance	1,021,577
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	1,601
Other comprehensive loss before reclassifications	(754)
Amounts reclassified from accumulated other comprehensive income	(24)
Tax effect	124
Net current period other comprehensive loss	(654)
Balance	947
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	8,539
Other comprehensive loss before reclassifications	(2,474)
Amounts reclassified from accumulated other comprehensive income	0
Tax effect	0
Net current period other comprehensive loss	(2,474)
Balance	6,065
AOCI Attributable to Parent [Member]
Balance	10,140
Other comprehensive loss before reclassifications	(3,228)
Amounts reclassified from accumulated other comprehensive income	(24)
Tax effect	124
Net current period other comprehensive loss	(3,128)
Balance	$ 7,012

Note 15 - Dividends and Divid_3

Note 15 - Dividends and Dividend Equivalents (Details Textual) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Dividends Payable, Current	$ 27.4	$ 22.6
Accrued Dividend Equivalents	$ 12.4	$ 11.7

Note 15 - Dividends and Divid_4

Note 15 - Dividends and Dividend Equivalents - Cash Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Dividend declared per share (in dollars per share)	$ 0.60	$ 0.50
Total amount	$ 27,393	$ 22,317