Monolithic Power Systems (MPWR) 10-Q 29 Jul 16 2016 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 25, 2016
Document Information [Line Items]
Entity Registrant Name	MONOLITHIC POWER SYSTEMS INC
Entity Central Index Key	1,280,452
Trading Symbol	mpwr
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding (in shares)		40,492,256
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 82,046	$ 90,860
Short-term investments	161,818	144,103
Accounts receivable, net	31,351	30,830
Inventories	69,919	63,209
Other current assets	3,980	2,926
Total current assets	349,114	331,928
Property and equipment, net	74,293	65,359
Long-term investments	5,294	5,361
Goodwill	6,571	6,571
Acquisition-related intangible assets, net	4,027	5,053
Deferred tax assets, net	644	672
Other long-term assets	28,698	16,341
Total assets	468,641	431,285
Current liabilities:
Accounts payable	19,140	13,487
Accrued compensation and related benefits	14,116	9,812
Accrued liabilities	18,855	19,984
Total current liabilities	52,111	43,283
Income tax liabilities	3,328	2,941
Other long-term liabilities	18,062	16,545
Total liabilities	73,501	62,769
Stockholders' equity:
Common stock and additional paid-in capital, $0.001 par value; shares authorized: 150,000; shares issued and outstanding: 40,480 and 39,689 as of June 30, 2016 and December 31, 2015, respectively	289,129	265,763
Retained earnings	105,883	101,287
Accumulated other comprehensive income	128	1,466
Total stockholders’ equity	395,140	368,516
Total liabilities and stockholders’ equity	$ 468,641	$ 431,285

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares shares in Thousands	Jun. 30, 2016	Dec. 31, 2015
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)	40,480	39,689
Common stock, shares outstanding (in shares)	40,480	39,689

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue	$ 94,079	$ 81,416	$ 178,591	$ 154,954
Cost of revenue	43,153	37,287	82,155	71,142
Gross profit	50,926	44,129	96,436	83,812
Operating expenses:
Research and development	17,876	15,743	35,197	31,781
Selling, general and administrative	21,531	17,964	39,299	35,482
Litigation expense (benefit), net	(8)	311	37	581
Total operating expenses	39,399	34,018	74,533	67,844
Income from operations	11,527	10,111	21,903	15,968
Interest and other income, net	597	235	1,140	877
Income before income taxes	12,124	10,346	23,043	16,845
Income tax provision	926	2,447	1,270	2,983
Net income	$ 11,198	$ 7,899	$ 21,773	$ 13,862
Net income per share:
Basic (in dollars per share)	$ 0.28	$ 0.20	$ 0.54	$ 0.35
Diluted (in dollars per share)	$ 0.27	$ 0.19	$ 0.52	$ 0.34
Weighted-average shares outstanding:
Basic (in shares)	40,387	39,570	40,208	39,337
Diluted (in shares)	41,716	40,745	41,681	40,670
Cash dividends declared per common share (in dollars per share)	$ 0.20	$ 0.20	$ 0.40	$ 0.40

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Auction Rate Securities [Member]
Other comprehensive income (loss), net of tax:
Available-for-sale Securities Adjustment, Net of Tax	$ (59)	$ (19)	$ (67)	$ (14)
Available-for-sale Securities [Member]
Other comprehensive income (loss), net of tax:
Available-for-sale Securities Adjustment, Net of Tax	52	4	270	35
Net income	11,198	7,899	21,773	13,862
Foreign currency translation adjustments	(2,039)	105	(1,541)	354
Total other comprehensive income (loss), net of tax	(2,046)	90	(1,338)	375
Comprehensive income	$ 9,152	$ 7,989	$ 20,435	$ 14,237

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Auction Rate Securities [Member]
Change in unrealized losses on securities, tax	$ 0	$ 0	$ 0	$ 0
Available-for-sale Securities [Member]
Change in unrealized losses on securities, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 21,773	$ 13,862
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangible assets	6,873	7,092
Loss on sales of property and equipment	58
(Gains) losses on investments, net	(244)	256
Deferred taxes, net	12
Excess tax benefits from equity awards	(361)	(2,648)
Stock-based compensation expense	20,726	18,716
Changes in operating assets and liabilities:
Accounts receivable	(520)	(1,134)
Inventories	(6,758)	(24,029)
Other assets	(10,417)	405
Accounts payable	7,176	4,687
Accrued liabilities	769	2,807
Income tax liabilities	395	1,122
Accrued compensation and related benefits	4,386	2,213
Net cash provided by operating activities	43,868	23,349
Cash flows from investing activities:
Property and equipment purchases	(18,678)	(6,655)
Purchases of short-term investments	(106,004)	(129,663)
Proceeds from sales of short-term investments	87,919	91,962
Contributions to employee deferred compensation plan, net	(1,623)	(2,775)
Net cash used in investing activities	(38,386)	(47,131)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(150)	(150)
Proceeds from Stock Options Exercised	1,040	6,680
Proceeds from Stock Plans	1,285	1,121
Repurchases of common shares		(18,129)
Dividends and dividend equivalents paid	(16,480)	(13,842)
Excess tax benefits from equity awards	361	2,648
Net cash used in financing activities	(13,944)	(21,672)
Effect of change in exchange rates	(352)	56
Net decrease in cash and cash equivalents	(8,814)	(45,398)
Cash and cash equivalents, beginning of period	90,860	126,266
Cash and cash equivalents, end of period	82,046	80,868
Supplemental disclosures for cash flow information:
Cash paid for taxes and interest	712	1,755
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for property and equipment purchases	472	681
Liability accrued for dividends and dividend equivalents	$ 9,312	$ 9,121

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. BASIS OF PRESENTATION 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-K for the year ended December 31, 2015, filed with the SEC on February 29, 2016. 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 Form 10-Q are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 or for any other future periods. Summary of Significant Accounting Policies There have been no changes to the Company’s significant accounting policies during the three and six months ended June 30, 2016 as compared to the significant accounting policies described in the Company’s audited consolidated financial statements included in the Annual Report on Form 10-K for the year ended December 31, 2015. Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, In March 2016, the FASB issued ASU No. 2016-09, Compensatio n—Stock Compensation : Improvements to Employee Share-Based Payment Accounting , excess tax benefits and tax deficiencies, forfeitures, statutory tax withholding requirements, as well as classification of excess tax benefits in the statements of cash flows. The standard will be effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted. The manner of application varies by the different provisions of the guidance, with certain provisions applied on a retrospective or modified retrospective approach, while others are applied prospectively. The Company is evaluating the impact of the adoption on its consolidated financial position, results of operations, cash flows and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases , In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers,

Note 2 - Stock-based Compensati

Note 2 - Stock-based Compensation	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	2. STOCK-BASED COMPENSATION Stock Plan The Board of Directors adopted the 2014 Equity Incentive Plan (the “2014 Plan”) in April 2013, and the stockholders approved it in June 2013. In October 2014, the Board of Directors approved certain amendments to the 2014 Plan. The 2014 Plan became effective on November 13, 2014 and provides for the issuance of up to 5.5 million shares. The 2014 Plan will expire on November 13, 2024. As of June 30, 2016, 3.9 million shares remained available for future issuance. Stock-Based Compensation Expense The Company recognized stock-based compensation expenses as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Cost of revenue $ 380 $ 284 $ 814 $ 526 Research and development 3,318 2,503 7,016 5,123 Selling, general and administrative 8,049 6,710 12,896 13,067 Total $ 11,747 $ 9,497 $ 20,726 $ 18,716 In the first quarter of 2016, the Company’s then Chief Financial Officer retired. As the service or performance conditions for certain of her unvested restricted stock units (“RSUs”) had not been satisfied at the time of her departure, the Company reversed previously accrued stock-based compensation expenses of approximately $2.9 million associated with the unvested shares and recorded the one-time credit in selling, general and administrative expenses for the three months ended March 31, 2016. RSUs The Company’s RSUs include time-based RSUs, RSUs with performance conditions (“PSUs”), RSUs with market and performance conditions (“MPSUs”), and RSUs with market conditions (“MSUs”). Vesting of all awards requires continued service for the Company. In addition, vesting of awards with performance conditions or market conditions is subject to the achievement of pre-determined performance goals. A summary of RSU activity is presented in the table below (in thousands, except per-share amounts): Time-Based RSUs Weighted- Average Grant Date Fair Value Per Share PSUs and MPSUs Weighted- Average Grant Date Fair Value Per Share MSUs Weighted- Average Grant Date Fair Value Per Share Total Weighted- Average Grant Date Fair Value Per Share Outstanding at January 1, 2016 499 $ 40.75 1,933 $ 38.99 1,800 $ 23.57 4,232 $ 32.64 Granted 116 $ 61.45 1,253 (1) $ 40.77 - $ - 1,369 $ 42.52 Performance adjustment - $ - (234 ) (2) $ 41.14 - $ - (234 ) $ 41.14 Released (142 ) $ 33.69 (563 ) $ 30.07 - $ - (705 ) $ 30.80 Forfeited (18 ) $ 42.92 (129 ) $ 36.82 (180 ) $ 23.57 (327 ) $ 029.87 Outstanding at June 30, 2016 455 $ 48.18 2,260 $ 42.10 1,620 $ 23.57 4,335 $ 35.81 (1) Amount reflects the maximum number of PSUs and MPSUs that can be earned assuming the achievement of the highest level of performance conditions. (2) Amount reflects the adjustment to the number of PSUs and MPSUs that have not been earned or may not be earned based on management’s probability assessment at each reporting period. The intrinsic value related to awards released for the three months ended June 30, 2016 and 2015 was $13.5 million and $8.4 million, respectively. The intrinsic value related to awards released for the six months ended June 30, 2016 and 2015 was $42.6 million and $33.9 million, respectively. As of June 30, 2016, the total intrinsic value of all outstanding awards was $296.1 million, based on the closing stock price of $68.32. As of June 30, 2016, unamortized compensation expense related to all outstanding awards was approximately $105.8 million with a weighted-average remaining recognition period of approximately four years. 2016 Time-Based RSUs: For the six months ended June 30, 2016, the Board of Directors granted 116,000 shares with service conditions to employees and non-employee directors. The RSUs vest over one year for non-employee directors and four years for employees, subject to continued employment with the Company. 2016 PSUs: In February 2016, the Board of Directors granted 285,000 shares to the executive officers, which represent a target number of RSUs to be awarded based on the Company’s average two-year (2016 and 2017) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as determined by the Semiconductor Industry Association (“2016 Executive PSUs”). The maximum number of 2016 Executive PSUs that an executive officer can earn is 300% of the target shares. 50% of the 2016 Executive PSUs will vest in the first quarter of 2018 if the pre-determined performance goals are met during the performance period and approved by the Compensation Committee. The remaining shares will vest over the following two years on a quarterly basis. Vesting is subject to the employees’ continued employment with the Company. In March 2016, the Company cancelled 32,000 shares granted in February 2016 as a result of the departure of its then Chief Financial Officer. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2016 Executive PSUs is approximately $30.0 million. In February 2016, the Board of Directors granted 64,000 shares to certain non-executive employees, which represent a target number of RSUs to be awarded based on the Company’s 2017 revenue goals for certain regions or product line divisions, or the Company’s average two-year (2016 and 2017) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as determined by the Semiconductor Industry Association (“2016 Non-Executive PSUs”). The maximum number of 2016 Non-Executive PSUs that an employee can earn is either 200% or 300% of the target shares, depending on the job classification of the employee. 50% of the 2016 Non-Executive PSUs will vest in the first quarter of 2018 if the pre-determined performance goals are met during the performance period and approved by the Compensation Committee. The remaining shares will vest over the following two years on an annual or quarterly basis. Vesting is subject to the employees’ continued employment with the Company. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2016 Non-Executive PSUs is approximately $6.2 million. The 2016 Executive PSUs and the 2016 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $20 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2016 Executive PSUs and the 2016 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $58.98, expected term of 2.6 years, expected volatility of 31.1% and risk-free interest rate of 0.9%. 2015 MPSUs: On December 31, 2015, the Board of Directors granted 127,000 shares to the executive officers and certain key employees, which represent a target number of RSUs to be awarded upon achievement of both market conditions and performance conditions (“2015 MPSUs”). The maximum number of 2015 MPSUs that an employee can earn is 500% of the target shares. The 2015 MPSUs consist of four separate tranches with various performance periods ending on December 31, 2019. The first tranche contains market conditions only, which require the achievement of five MPS stock price targets ranging from $71.36 to $95.57 over a four-year period. The second, third and fourth tranches contain both market conditions and performance conditions. Each tranche requires the achievement of five MPS stock price targets to be measured against a base price equal to the greater of: (1) the average closing stock price during the 20 consecutive trading days immediately before the start of the measurement period for that tranche, or (2) the closing stock price immediately before the start of the measurement period for that tranche. In addition, each of the second, third and fourth tranches requires the achievement of one of following six operating metrics: 1. Successful implementation of full digital solutions vs. current analog topology for certain products. 2. Successful implementation and adoption by a key player of an integrated, software-based, field-oriented-control with 3D hall sensor to motor driver. 3. Successful implementation of certain advanced power analog processes. 4. Successful design wins and achievement of a specific level of revenue with a global networking customer. 5. Achievement of a specific level of revenue with a global electronics manufacturer. 6. Achievement of a specific level of market share with certain core power products. Subject to the employees’ continued employment with the Company, the 2015 MPSUs will fully vest on January 1, 2020 if the pre-determined individual market and performance goals in each tranche are met during the performance periods and approved by the Compensation Committee. In addition, the 2015 MPSUs contain post-vesting restrictions on sales of the vested shares by employees for up to two years. The Company determined the grant date fair value of the 2015 MPSUs using a Monte Carlo simulation model with the following weighted-average assumptions: stock price of $61.35, expected volatility of 33.2%, risk-free interest rate of 1.3%, and an illiquidity discount of 7.8% to account for the post-vesting sales restrictions. In March 2016, the Company cancelled 13,000 shares of the 2015 MPSUs as a result of the departure of its then Chief Financial Officer. Assuming the achievement of all of the required performance goals, the total stock-based compensation cost for the 2015 MPSUs is approximately $24.6 million to be recognized as follows: $8.3 million for the first tranche, $4.5 million for the second tranche, $5.2 million for the third tranche, and $6.6 million for the fourth tranche. For the first tranche, stock-based compensation expense is being recognized over four years even if the market conditions are not satisfied. For the second, third and fourth tranches, stock-based compensation expense for each tranche will be recognized depending upon the number of the operating metrics management deems probable of achievement in each reporting period. As of March 31, 2016 and June 30, 2016, based on management’s assessment, two of the six operating metrics were considered probable of being achieved during the performance period. Accordingly, stock-based compensation expense is being recognized for the second and third tranches over four years. Stock Options As of June 30, 2016, outstanding and vested options totaled 34,000 shares, with a weighted-average exercise price of $15.68, a weighted-average remaining contractual term of 1.5 years, and an aggregate intrinsic value of $1.8 million. Total intrinsic value of options exercised was $1.4 million and $12.9 million for the three months ended June 30, 2016 and 2015, respectively. Total intrinsic value of options exercised was $2.5 million and $15.4 million for the six months ended June 30, 2016 and 2015, respectively. The net cash proceeds from the exercise of stock options were $1.0 million and $6.7 million for the six months ended June 30, 2016 and 2015, respectively. As of June 30, 2016, there was no unamortized compensation expense. Employee Stock Purchase Plan (“ESPP”) No shares were issued under the ESPP for the three months ended June 30, 2016 and 2015. For the six months ended June 30, 2016 and 2015, 29,000 and 30,000 shares, respectively, were issued under the ESPP. As of June 30, 2016, 4.7 million shares were available for future issuance. The intrinsic value of shares issued was $0.4 million for both the six months ended June 30, 2016 and 2015. As of June 30, 2016, the unamortized expense was $0.1 million, which will be recognized through the third quarter of 2016. The Black-Scholes model was used to value the employee stock purchase rights with the following weighted-average assumptions: Six Months Ended June 30, 2016 2015 Expected term (years) 0.5 0.5 Expected volatility 29.7 % 35.7 % Risk-free interest rate 0.4 % 0.1 % Dividend yield 1.4 % 1.2 % Cash proceeds from the shares issued under the ESPP were $1.3 million and $1.1 million for the six months ended June 30, 2016 and 2015, respectively.

Note 3 - Balance Sheet Componen

Note 3 - Balance Sheet Components	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Supplemental Balance Sheet Disclosures [Text Block]	3. BALANCE SHEET COMPONENTS Inventories Inventories consist of the following (in thousands): June 30, December 31, 2016 2015 Raw materials $ 14,423 $ 14,907 Work in process 21,640 21,177 Finished goods 33,856 27,125 Total $ 69,919 $ 63,209 When the Company records a write-down on inventory, it establishes a new, lower cost basis for that inventory, and subsequent changes in facts and circumstances will not result in the restoration or increase in that newly established cost basis. Other Long-Term Assets Other long-term assets consist of the following (in thousands): June 30, December 31, 2016 2015 Deferred compensation plan assets $ 16,217 $ 13,985 Prepaid wafer purchase 10,000 - Other prepaid expense 1,282 1,257 Other 1,199 1,099 Total $ 28,698 $ 16,341 Accrued Liabilities Accrued liabilities consist of the following (in thousands): June 30, December 31, 2016 2015 Dividends and dividend equivalents $ 8,852 $ 8,675 Deferred revenue and customer prepayments 4,916 5,236 Stock rotation reserve 1,641 2,372 Warranty 950 289 Commissions 846 763 Sales rebate 221 268 Income tax payable 124 465 Other 1,305 1,916 Total $ 18,855 $ 19,984 A roll-forward of the warranty reserve is as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Balance at beginning of period $ 336 $ 296 $ 289 $ 240 Warranty provision for product sales 734 81 819 155 Settlement made (42 ) (154 ) (42 ) (154 ) Unused warranty provision (78 ) (18 ) (116 ) (36 ) Balance at end of period $ 950 $ 205 $ 950 $ 205 Other Long-Term Liabilities Other long-term liabilities consist of the following (in thousands): June 30, December 31, 2016 2015 Deferred compensation plan liabilities $ 15,395 $ 14,147 Dividend equivalents 2,539 2,019 Other 128 379 Total $ 18,062 $ 16,545

Note 4 - Goodwill and Acquisiti

Note 4 - Goodwill and Acquisition-related Intangible Assets, Net	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Goodwill and Intangible Assets Disclosure [Text Block]	4. GOODWILL AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET There have been no changes in the balance of goodwill during the three and six months ended June 30, 2016. Acquisition-related intangible assets subject to amortization consist of the following (in thousands): June 30, 2016 Gross Amount Accumulated Amortization Net Amount Know-how $ 1,018 $ (399 ) $ 619 Developed technologies 6,466 (3,058 ) 3,408 Total $ 7,484 $ (3,457 ) $ 4,027 December 31, 2015 Gross Amount Accumulated Amortization Net Amount Know-how $ 1,018 $ (297 ) $ 721 Developed technologies 6,466 (2,134 ) 4,332 Total $ 7,484 $ (2,431 ) $ 5,053 Amortization expense is recorded in cost of revenue in the Condensed Consolidated Statements of Operations. For the three months ended June 30, 2016 and 2015, amortization expense totaled $0.5 million and $0.4 million, respectively. For the six months ended June 30, 2016 and 2015, amortization expense totaled $1.0 million and $0.7 million, respectively. As of June 30, 2016, the estimated future amortization expense was as follows (in thousands): 2016 (remaining six months) $ 1,025 2017 2,051 2018 841 2019 110 Total $ 4,027

Note 5 - Net Income Per Share

Note 5 - Net Income Per Share	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Earnings Per Share [Text Block]	5. NET INCOME PER SHARE 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 stock, 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 outstanding RSUs contain forfeitable rights to receive dividend equivalents, which are accumulated and payable to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill their service requirement during the vesting periods. Accordingly, these awards are not treated as participating securities in the net income per share calculation. The following table sets forth the computation of basic and diluted net income per share (in thousands, except per-share amounts): Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Numerator: Net income $ 11,198 $ 7,899 $ 21,773 $ 13,862 Denominator: Weighted-average outstanding shares used to compute basic net income per share 40,387 39,570 40,208 39,337 Effect of dilutive securities 1,329 1,175 1,473 1,333 Weighted-average outstanding shares used to compute diluted net income per share 41,716 40,745 41,681 40,670 Net income per share: Basic $ 0.28 $ 0.20 $ 0.54 $ 0.35 Diluted $ 0.27 $ 0.19 $ 0.52 $ 0.34 Anti-dilutive common stock equivalents were not material in any of the periods presented.

Note 6 - Segment and Geographic

Note 6 - Segment and Geographic Information	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	6. SEGMENT AND GEOGRAPHIC INFORMATION The Company operates in one reportable segment that includes the design, development, marketing and sale of high-performance power solutions for the communications, storage and computing, consumer and industrial markets. The Company’s chief operating decision maker is its chief executive officer, who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company derives a majority of its revenue from sales to customers located outside North America, with geographic revenue based on the customers’ ship-to locations. The Company sells its products primarily through third-party distributors and value-added resellers, and directly to original equipment manufacturers, original design manufacturers and electronic manufacturing service providers. The following table summarizes those customers with sales greater than 10% of the Company's total revenue: Three Months Ended June 30, Six Months Ended June 30, Customer 2016 2015 2016 2015 Distributor A 24 % 23 % 22 % 24 % The following table summarizes those customers with accounts receivable balances greater than 10% of the Company’s total accounts receivable: June 30, December 31, Customer 2016 2015 Distributor A 27 % 28 % Distributor B 11 % 17 % Both of the customers are third-party distributors. The Company’s agreements with these distributors were made in the ordinary course of business and may be terminated with or without cause by these distributors with advance notice. Although the Company may experience a short-term disruption in the distribution of its products and a short-term decline in revenue if its agreement with either of these distributors was terminated, the Company believes that such termination would not have a material adverse effect on its financial statements because it would be able to engage alternative distributors, resellers and other distribution channels to deliver its products to end customers within a few quarters following the termination of the agreement with the distributor. The following is a summary of revenue by geographic regions (in thousands): Three Months Ended June 30, Six Months Ended June 30, Country or Region 2016 2015 2016 2015 China $ 60,928 $ 53,450 $ 113,316 $ 99,252 Taiwan 10,160 10,143 19,015 21,172 Europe 7,054 5,317 14,039 10,432 Korea 7,024 5,109 14,117 9,354 Southeast Asia 3,501 3,336 7,840 7,075 Japan 3,037 2,412 5,687 4,297 United States 2,303 1,566 4,449 3,259 Other 72 83 128 113 Total $ 94,079 $ 81,416 $ 178,591 $ 154,954 The following is a summary of revenue by product family (in thousands): Three Months Ended June 30, Six Months Ended June 30, Product Family 2016 2015 2016 2015 DC to DC products $ 84,221 $ 73,195 $ 161,339 $ 139,492 Lighting control products 9,858 8,221 17,252 15,462 Total $ 94,079 $ 81,416 $ 178,591 $ 154,954 The following is a summary of long-lived assets by geographic regions (in thousands): June 30, December 31, Country 2016 2015 China $ 49,959 $ 40,738 United States 41,983 40,405 Bermuda 20,598 11,624 Other 1,049 557 Total $ 113,589 $ 93,324

Note 7 - Litigation

Note 7 - Litigation	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Legal Matters and Contingencies [Text Block]	7. LITIGATION The Company is a party to actions and proceedings in the ordinary course of business, including litigation regarding its shareholders and its intellectual property, 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 require the expenditure of significant funds and the diversion of other resources to prosecute and defend. The Company defends itself vigorously against any such claims. As of June 30, 2016, there were no material pending legal proceedings to which the Company was a party.

Note 8 - Cash, Cash Equivalents

Note 8 - Cash, Cash Equivalents and Investments	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Cash, Cash Equivalents, and Marketable Securities [Text Block]	8. CASH, CASH EQUIVALENTS AND INVESTMENTS The following is a summary of the Company’s cash, cash equivalents and short-term and long-term investments (in thousands): June 30, December 31, 2016 2015 Cash, cash equivalents and investments: Cash $ 54,182 $ 58,217 Money market funds 27,864 31,640 Certificates of deposit 7,525 21,574 Corporate debt securities 7,581 - U.S. treasuries and government agency bonds 146,712 123,532 Auction-rate securities backed by student-loan notes 5,294 5,361 Total $ 249,158 $ 240,324 June 30, December 31, 2016 2015 Reported as: Cash and cash equivalents $ 82,046 $ 90,860 Short-term investments 161,818 144,103 Long-term investments 5,294 5,361 Total $ 249,158 $ 240,324 The contractual maturities of the Company’s short-term and long-term available-for-sale investments are as follows (in thousands): June 30, December 31, 2016 2015 Due in less than 1 year $ 131,926 $ 110,898 Due in 1 - 5 years 29,892 33,205 Due in greater than 5 years 5,294 5,361 Total $ 167,112 $ 149,464 The following tables summarize the unrealized gain and loss positions related to the Company’s investments in marketable securities designated as available-for sale (in thousands): June 30, 2016 Adjusted Cost Unrealized Gains Unrealized Losses Total Fair Value Fair Value of Investments in Unrealized Loss Position Money market funds $ 27,864 $ - $ - $ 27,864 $ - Certificates of deposit 7,525 - - 7,525 - Corporate debt securities 7,570 11 - 7,581 - U.S. treasuries and government agency bonds 146,619 97 (4 ) 146,712 16,002 Auction-rate securities backed by student-loan notes 5,570 - (276 ) 5,294 5,294 Total $ 195,148 $ 108 $ (280 ) $ 194,976 $ 21,296 December 31, 2015 Adjusted Cost Unrealized Gains Unrealized Losses Total Fair Value Fair Value of Investments in Unrealized Loss Position Money market funds $ 31,640 $ - $ - $ 31,640 $ - Certificates of deposit 21,574 - - 21,574 - U.S. treasuries and government agency bonds 123,698 4 (170 ) 123,532 110,720 Auction-rate securities backed by student-loan notes 5,570 - (209 ) 5,361 5,361 Total $ 182,482 $ 4 $ (379 ) $ 182,107 $ 116,081

Note 9 - Fair Value Measurement

Note 9 - Fair Value Measurements	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Fair Value Disclosures [Text Block]	9. FAIR VALUE MEASUREMENTS The following table details the fair value measurement of the financial assets (in thousands): Fair Value Measurement at June 30, 2016 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total Level 1 Level 2 Level 3 Money market funds $ 27,864 $ 27,864 $ - $ - Certificates of deposit 7,525 - 7,525 - Corporate debt securities 7,581 - 7,581 - U.S. treasuries and government agency bonds 146,712 - 146,712 - Auction-rate securities backed by student-loan notes 5,294 - - 5,294 Mutual funds under deferred compensation plan 10,162 10,162 - - Total $ 205,138 $ 38,026 $ 161,818 $ 5,294 Fair Value Measurement at December 31, 2015 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total Level 1 Level 2 Level 3 Money market funds $ 31,640 $ 31,640 $ - $ - Certificates of deposit 21,574 - 21,574 - U.S. treasuries and government agency bonds 123,532 - 123,532 - Auction-rate securities backed by student-loan notes 5,361 - - 5,361 Mutual funds under deferred compensation plan 8,279 8,279 - - Total $ 190,386 $ 39,919 $ 145,106 $ 5,361 The Company’s level 3 assets consist of government-backed student loan auction-rate securities, with interest rates that reset through a Dutch auction every 7 to 35 days and which became illiquid in 2008. The following table provides a rollforward of the fair value of the auction-rate securities (in thousands): Balance at January 1, 2016 $ 5,361 Change in unrealized loss included in other comprehensive income (67 ) Balance at June 30, 2016 $ 5,294 The Company determined the fair value of the auction-rate securities using a discounted cash flow model with the following assumptions: June 30, December 31, 2016 2015 Time-to-liquidity (months) 24 24 Expected return 2.1% 2.9% Discount rate 4.2% - 7.2% 4.3% - 7.3%

Note 10 - Deferred Compensation

Note 10 - Deferred Compensation Plan	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Compensation and Employee Benefit Plans [Text Block]	10. DEFERRED COMPENSATION PLAN The Company has a non-qualified, unfunded deferred compensation plan, which provides certain key employees, including executive management, with the ability to defer the receipt of compensation in order to accumulate funds for retirement on a tax deferred basis. The Company does not make contributions to the plan or guarantee returns on the investments. The Company is responsible for the plan’s administrative expenses. Participants’ deferrals and investment gains and losses remain as the Company’s liabilities and the underlying assets are subject to claims of general creditors. The following table summarizes the deferred compensation plan amounts in the Condensed Consolidated Balance Sheets (in thousands): June 30, December 31, 2016 2015 Deferred compensation plan assets reported in: Other long-term assets $ 16,217 $ 13,985 Deferred compensation plan liabilities reported in: Accrued compensation and related benefits (short-term) $ 952 $ - Other long-term liabilities 15,395 14,147 Total $ 16,347 $ 14,147

Note 11 - Income Taxes

Note 11 - Income Taxes	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Income Tax Disclosure [Text Block]	11. INCOME TAXES The income tax provision for the three and six months ended June 30, 2016 was $0.9 million, or 7.6% of the pre-tax income, and $1.3 million, or 5.5% of the pre-tax income, respectively. The effective tax rate differed from the federal statutory rate primarily because foreign income was taxed at lower rates, and because of the benefit that the Company realized from the release of RSUs. In addition, the effective tax rate was impacted by changes in the valuation allowance. The income tax provision for the three and six months ended June 30, 2015 was $2.4 million, or 23.7% of the pre-tax income, and $3.0 million, or 17.7% of the pre-tax income, respectively. The Company recorded a one-time net charge of $2.7 million to the income tax provision related to the resolution of the income tax audits for the tax years 2005 through 2007 in the second quarter of 2015. In addition to the impact of this charge, the effective tax rate differed from the federal statutory rate primarily because the foreign income was taxed at lower rates, and because of the benefit that the Company realized from stock option exercises and the release of RSUs, and from the release of an income tax reserve where the statute of limitations expired. In addition, the effective tax rate was impacted by changes in the valuation allowance. On July 27, 2015, in Altera Corp. v. Commissioner Unrecognized Tax Benefits As of June 30, 2016, the Company had $14.0 million of unrecognized tax benefits, $3.8 million of which would affect its effective tax rate if recognized after considering the valuation allowance. At December 31, 2015, the Company had $12.1 million of unrecognized tax benefits, $2.7 million of which would affect its effective tax rate if recognized after considering the valuation allowance. Uncertain tax positions relate to the allocation of income and deductions among the Company’s global entities and to the determination of the research and development tax credit. It is reasonably possible that over the next twelve-month period, the Company may experience increases or decreases in its unrecognized tax benefits. However, it is not possible to determine either the magnitude or the range of increases or decreases at this time. The Company recognizes interest and penalties, if any, related to uncertain tax positions in its income tax provision. As of June 30, 2016 and December 31, 2015, the Company has approximately $0.3 million and $0.2 million of accrued interest related to uncertain tax positions, respectively, which were recorded in long-term income tax liabilities in the Condensed Consolidated Balance Sheets. Income Tax Examination The Company is subject to examination of its income tax returns by the Internal Revenue Service (“IRS”) and other tax authorities. In May 2016, the IRS notified the Company that its federal income tax return for the year ended December 31, 2014 is under examination. The opening conference with the IRS for the examination is scheduled in August 2016.

Note 12 - Accumulated Other Com

Note 12 - Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Comprehensive Income (Loss) Note [Text Block]	12. ACCUMULATED OTHER COMPREHENSIVE INCOME The following table summarizes the changes in accumulated other comprehensive income (in thousands): Unrealized Losses on Auction-Rate Securities Unrealized Gains (Losses) on Other Available-for-Sale Securities Foreign Currency Translation Adjustments Total Balance as of January 1, 2016 $ (209 ) $ (166 ) $ 1,841 $ 1,466 Other comprehensive income (loss) before reclassifications (8 ) 220 498 710 Amounts reclassified from accumulated other comprehensive income - (2 ) - (2 ) Net current period other comprehensive income (loss) (8 ) 218 498 708 Balance as of March 31, 2016 (217 ) 52 2,339 2,174 Other comprehensive income (loss) before reclassifications (59 ) 53 (2,039 ) (2,045 ) Amounts reclassified from accumulated other comprehensive income - (1 ) - (1 ) Net current period other comprehensive income (loss) (59 ) 52 (2,039 ) (2,046 ) Balance as of June 30, 2016 $ (276 ) $ 104 $ 300 $ 128 The amounts reclassified from accumulated other comprehensive income were recorded in interest and other income, net, in the Condensed Consolidated Statement of Operations.

Note 13 - Stock Repurchase

Note 13 - Stock Repurchase	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Common Stock Repurchases [Text Block]	13. STOCK REPURCHASE In July 2013, the Board of Directors approved a stock repurchase program that authorized the Company to repurchase up to $100 million in the aggregate of its common stock through June 30, 2015. In April 2015, the Board of Directors approved an extension of the program through December 31, 2015. The stock repurchase program expired as of December 31, 2015 with a remaining unused balance of $5.9 million. Shares were retired upon repurchase under the program. In February 2016, the Board of Directors approved a new stock repurchase program that authorized the Company to repurchase up to $50 million in the aggregate of its common stock through December 31, 2016. Shares are retired upon repurchase under the program. The Company did not repurchase any shares for the three and six months ended June 30, 2016. For the three months ended June 30, 2015, the Company repurchased 0.1 million shares for $7.7 million at an average price of $52.19. For the six months ended June 30, 2015, the Company repurchased 0.4 million shares for $18.1 million at an average price of $51.70.

Note 14 - Dividends and Dividen

Note 14 - Dividends and Dividend Equivalents	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Dividends And Dividend Equivalents [Text Block]	14. DIVIDENDS AND DIVIDEND EQUIVALENTS Cash Dividend Program In June 2014, the Board of Directors approved a dividend program pursuant to which the Company intends to pay quarterly cash dividends on its common stock. Stockholders of record as of the last day of the quarter are entitled to receive the quarterly cash dividends when and if declared by the Board of Directors, which are generally payable on the 15th of the following month. The Board of Directors declared the following cash dividends (in thousands, except per-share amounts): Dividend Declared Total 2016: First quarter $ 0.20 $ 8,047 Second quarter $ 0.20 $ 8,096 2015: First quarter $ 0.20 $ 7,854 Second quarter $ 0.20 $ 7,925 As of June 30, 2016 and December 31, 2015, accrued dividends totaled $8.1 million and $7.9 million, respectively. 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, statutory requirements of Delaware law, compliance with the terms of future indebtedness and credit facilities and other factors that the Board of Directors may deem relevant, as well as a determination that cash dividends are in the best interests of the stockholders. The Company anticipates that the cash used for future dividends will come from its current domestic cash and cash generated from ongoing U.S. operations. If cash held by the Company’s international subsidiaries is needed for the payment of dividends, the Company may be required to accrue and pay U.S. taxes to repatriate the funds. Cash Dividend Equivalent Rights Under the Company’s stock plans, outstanding 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 are payable to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill their service requirement during the vesting periods. As of June 30, 2016 and December 31, 2015, accrued dividend equivalents totaled $3.3 million and $2.8 million, respectively, which will be payable to the employees when the underlying RSUs vest.

Note 15 - Subsequent Event

Note 15 - Subsequent Event	6 Months Ended
	Jun. 30, 2016
Notes to Financial Statements
Subsequent Events [Text Block]	15. SUBSEQUENT EVENT 2016 PSUs In July 2016, the Company appointed Mr. Bernie Blegen as its new Chief Financial Officer. In connection with the appointment, the Board granted 12,000 shares to Mr. Blegen, subject to the terms and conditions of the 2016 Executive PSUs (see Note 2).

Significant Accounting Policies

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	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-K for the year ended December 31, 2015, filed with the SEC on February 29, 2016. 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 Form 10-Q are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 or for any other future periods.
New Accounting Pronouncements, Policy [Policy Text Block]	In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, In March 2016, the FASB issued ASU No. 2016-09, Compensatio n—Stock Compensation : Improvements to Employee Share-Based Payment Accounting , excess tax benefits and tax deficiencies, forfeitures, statutory tax withholding requirements, as well as classification of excess tax benefits in the statements of cash flows. The standard will be effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted. The manner of application varies by the different provisions of the guidance, with certain provisions applied on a retrospective or modified retrospective approach, while others are applied prospectively. The Company is evaluating the impact of the adoption on its consolidated financial position, results of operations, cash flows and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases , In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers,

Note 2 - Stock-based Compensa24

Note 2 - Stock-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Cost of revenue $ 380 $ 284 $ 814 $ 526 Research and development 3,318 2,503 7,016 5,123 Selling, general and administrative 8,049 6,710 12,896 13,067 Total $ 11,747 $ 9,497 $ 20,726 $ 18,716
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	Time-Based RSUs Weighted- Average Grant Date Fair Value Per Share PSUs and MPSUs Weighted- Average Grant Date Fair Value Per Share MSUs Weighted- Average Grant Date Fair Value Per Share Total Weighted- Average Grant Date Fair Value Per Share Outstanding at January 1, 2016 499 $ 40.75 1,933 $ 38.99 1,800 $ 23.57 4,232 $ 32.64 Granted 116 $ 61.45 1,253 (1) $ 40.77 - $ - 1,369 $ 42.52 Performance adjustment - $ - (234 ) (2) $ 41.14 - $ - (234 ) $ 41.14 Released (142 ) $ 33.69 (563 ) $ 30.07 - $ - (705 ) $ 30.80 Forfeited (18 ) $ 42.92 (129 ) $ 36.82 (180 ) $ 23.57 (327 ) $ 029.87 Outstanding at June 30, 2016 455 $ 48.18 2,260 $ 42.10 1,620 $ 23.57 4,335 $ 35.81
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	Six Months Ended June 30, 2016 2015 Expected term (years) 0.5 0.5 Expected volatility 29.7 % 35.7 % Risk-free interest rate 0.4 % 0.1 % Dividend yield 1.4 % 1.2 %

Note 3 - Balance Sheet Compon25

Note 3 - Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Inventory, Current [Table Text Block]	June 30, December 31, 2016 2015 Raw materials $ 14,423 $ 14,907 Work in process 21,640 21,177 Finished goods 33,856 27,125 Total $ 69,919 $ 63,209
Schedule of Other Assets, Noncurrent [Table Text Block]	June 30, December 31, 2016 2015 Deferred compensation plan assets $ 16,217 $ 13,985 Prepaid wafer purchase 10,000 - Other prepaid expense 1,282 1,257 Other 1,199 1,099 Total $ 28,698 $ 16,341
Schedule of Accrued Liabilities [Table Text Block]	June 30, December 31, 2016 2015 Dividends and dividend equivalents $ 8,852 $ 8,675 Deferred revenue and customer prepayments 4,916 5,236 Stock rotation reserve 1,641 2,372 Warranty 950 289 Commissions 846 763 Sales rebate 221 268 Income tax payable 124 465 Other 1,305 1,916 Total $ 18,855 $ 19,984
Schedule of Product Warranty Liability [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Balance at beginning of period $ 336 $ 296 $ 289 $ 240 Warranty provision for product sales 734 81 819 155 Settlement made (42 ) (154 ) (42 ) (154 ) Unused warranty provision (78 ) (18 ) (116 ) (36 ) Balance at end of period $ 950 $ 205 $ 950 $ 205
Other Noncurrent Liabilities [Table Text Block]	June 30, December 31, 2016 2015 Deferred compensation plan liabilities $ 15,395 $ 14,147 Dividend equivalents 2,539 2,019 Other 128 379 Total $ 18,062 $ 16,545

Note 4 - Goodwill and Acquisi26

Note 4 - Goodwill and Acquisition-related Intangible Assets, Net (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	June 30, 2016 Gross Amount Accumulated Amortization Net Amount Know-how $ 1,018 $ (399 ) $ 619 Developed technologies 6,466 (3,058 ) 3,408 Total $ 7,484 $ (3,457 ) $ 4,027 December 31, 2015 Gross Amount Accumulated Amortization Net Amount Know-how $ 1,018 $ (297 ) $ 721 Developed technologies 6,466 (2,134 ) 4,332 Total $ 7,484 $ (2,431 ) $ 5,053
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	2016 (remaining six months) $ 1,025 2017 2,051 2018 841 2019 110 Total $ 4,027

Note 5 - Net Income Per Share (

Note 5 - Net Income Per Share (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Numerator: Net income $ 11,198 $ 7,899 $ 21,773 $ 13,862 Denominator: Weighted-average outstanding shares used to compute basic net income per share 40,387 39,570 40,208 39,337 Effect of dilutive securities 1,329 1,175 1,473 1,333 Weighted-average outstanding shares used to compute diluted net income per share 41,716 40,745 41,681 40,670 Net income per share: Basic $ 0.28 $ 0.20 $ 0.54 $ 0.35 Diluted $ 0.27 $ 0.19 $ 0.52 $ 0.34

Note 6 - Segment and Geograph28

Note 6 - Segment and Geographic Information (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, Customer 2016 2015 2016 2015 Distributor A 24 % 23 % 22 % 24 %
Schedule Of Accounts Receivable, By Major Customers, By Reporting Segments [Table Text Block]	June 30, December 31, Customer 2016 2015 Distributor A 27 % 28 % Distributor B 11 % 17 %
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, Country or Region 2016 2015 2016 2015 China $ 60,928 $ 53,450 $ 113,316 $ 99,252 Taiwan 10,160 10,143 19,015 21,172 Europe 7,054 5,317 14,039 10,432 Korea 7,024 5,109 14,117 9,354 Southeast Asia 3,501 3,336 7,840 7,075 Japan 3,037 2,412 5,687 4,297 United States 2,303 1,566 4,449 3,259 Other 72 83 128 113 Total $ 94,079 $ 81,416 $ 178,591 $ 154,954
Revenue from External Customers by Products and Services [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, Product Family 2016 2015 2016 2015 DC to DC products $ 84,221 $ 73,195 $ 161,339 $ 139,492 Lighting control products 9,858 8,221 17,252 15,462 Total $ 94,079 $ 81,416 $ 178,591 $ 154,954
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]	June 30, December 31, Country 2016 2015 China $ 49,959 $ 40,738 United States 41,983 40,405 Bermuda 20,598 11,624 Other 1,049 557 Total $ 113,589 $ 93,324

Note 8 - Cash, Cash Equivalen29

Note 8 - Cash, Cash Equivalents and Investments (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Fair Value, by Balance Sheet Grouping [Table Text Block]	June 30, December 31, 2016 2015 Cash, cash equivalents and investments: Cash $ 54,182 $ 58,217 Money market funds 27,864 31,640 Certificates of deposit 7,525 21,574 Corporate debt securities 7,581 - U.S. treasuries and government agency bonds 146,712 123,532 Auction-rate securities backed by student-loan notes 5,294 5,361 Total $ 249,158 $ 240,324 June 30, December 31, 2016 2015 Reported as: Cash and cash equivalents $ 82,046 $ 90,860 Short-term investments 161,818 144,103 Long-term investments 5,294 5,361 Total $ 249,158 $ 240,324
Investments Classified by Contractual Maturity Date [Table Text Block]	June 30, December 31, 2016 2015 Due in less than 1 year $ 131,926 $ 110,898 Due in 1 - 5 years 29,892 33,205 Due in greater than 5 years 5,294 5,361 Total $ 167,112 $ 149,464
Unrealized Gain (Loss) on Investments [Table Text Block]	June 30, 2016 Adjusted Cost Unrealized Gains Unrealized Losses Total Fair Value Fair Value of Investments in Unrealized Loss Position Money market funds $ 27,864 $ - $ - $ 27,864 $ - Certificates of deposit 7,525 - - 7,525 - Corporate debt securities 7,570 11 - 7,581 - U.S. treasuries and government agency bonds 146,619 97 (4 ) 146,712 16,002 Auction-rate securities backed by student-loan notes 5,570 - (276 ) 5,294 5,294 Total $ 195,148 $ 108 $ (280 ) $ 194,976 $ 21,296 December 31, 2015 Adjusted Cost Unrealized Gains Unrealized Losses Total Fair Value Fair Value of Investments in Unrealized Loss Position Money market funds $ 31,640 $ - $ - $ 31,640 $ - Certificates of deposit 21,574 - - 21,574 - U.S. treasuries and government agency bonds 123,698 4 (170 ) 123,532 110,720 Auction-rate securities backed by student-loan notes 5,570 - (209 ) 5,361 5,361 Total $ 182,482 $ 4 $ (379 ) $ 182,107 $ 116,081

Note 9 - Fair Value Measureme30

Note 9 - Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	Fair Value Measurement at June 30, 2016 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total Level 1 Level 2 Level 3 Money market funds $ 27,864 $ 27,864 $ - $ - Certificates of deposit 7,525 - 7,525 - Corporate debt securities 7,581 - 7,581 - U.S. treasuries and government agency bonds 146,712 - 146,712 - Auction-rate securities backed by student-loan notes 5,294 - - 5,294 Mutual funds under deferred compensation plan 10,162 10,162 - - Total $ 205,138 $ 38,026 $ 161,818 $ 5,294 Fair Value Measurement at December 31, 2015 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total Level 1 Level 2 Level 3 Money market funds $ 31,640 $ 31,640 $ - $ - Certificates of deposit 21,574 - 21,574 - U.S. treasuries and government agency bonds 123,532 - 123,532 - Auction-rate securities backed by student-loan notes 5,361 - - 5,361 Mutual funds under deferred compensation plan 8,279 8,279 - - Total $ 190,386 $ 39,919 $ 145,106 $ 5,361
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Balance at January 1, 2016 $ 5,361 Change in unrealized loss included in other comprehensive income (67 ) Balance at June 30, 2016 $ 5,294
Schedule Of Level 3 Assumptions [Table Text Block]	June 30, December 31, 2016 2015 Time-to-liquidity (months) 24 24 Expected return 2.1% 2.9% Discount rate 4.2% - 7.2% 4.3% - 7.3%

Note 10 - Deferred Compensati31

Note 10 - Deferred Compensation Plan (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Deferred Compensation Plan [Table Text Block]	June 30, December 31, 2016 2015 Deferred compensation plan assets reported in: Other long-term assets $ 16,217 $ 13,985 Deferred compensation plan liabilities reported in: Accrued compensation and related benefits (short-term) $ 952 $ - Other long-term liabilities 15,395 14,147 Total $ 16,347 $ 14,147

Note 12 - Accumulated Other C32

Note 12 - Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Unrealized Losses on Auction-Rate Securities Unrealized Gains (Losses) on Other Available-for-Sale Securities Foreign Currency Translation Adjustments Total Balance as of January 1, 2016 $ (209 ) $ (166 ) $ 1,841 $ 1,466 Other comprehensive income (loss) before reclassifications (8 ) 220 498 710 Amounts reclassified from accumulated other comprehensive income - (2 ) - (2 ) Net current period other comprehensive income (loss) (8 ) 218 498 708 Balance as of March 31, 2016 (217 ) 52 2,339 2,174 Other comprehensive income (loss) before reclassifications (59 ) 53 (2,039 ) (2,045 ) Amounts reclassified from accumulated other comprehensive income - (1 ) - (1 ) Net current period other comprehensive income (loss) (59 ) 52 (2,039 ) (2,046 ) Balance as of June 30, 2016 $ (276 ) $ 104 $ 300 $ 128

Note 14 - Dividends and Divid33

Note 14 - Dividends and Dividend Equivalents (Tables)	6 Months Ended
	Jun. 30, 2016
Notes Tables
Schedule of Dividends Payable [Table Text Block]	Dividend Declared Total 2016: First quarter $ 0.20 $ 8,047 Second quarter $ 0.20 $ 8,096 2015: First quarter $ 0.20 $ 7,854 Second quarter $ 0.20 $ 7,925

Note 2 - Stock-based Compensa34

Note 2 - Stock-based Compensation (Details Textual)	1 Months Ended			3 Months Ended			6 Months Ended		12 Months Ended
	Mar. 31, 2016shares	Feb. 29, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Jun. 30, 2016USD ($)$ / sharesshares	Mar. 31, 2016USD ($)	Jun. 30, 2015USD ($)shares	Jun. 30, 2016USD ($)$ / sharesshares	Jun. 30, 2015USD ($)shares	Dec. 31, 2015$ / shares	Nov. 13, 2014shares
Employee Stock Purchase Plan [Member]
Stock Issued During Period, Shares, Employee Stock Purchase Plans | shares				0		0	29,000	30,000
Employee Stock Purchase Plan Shares Issued, Intrinsic Value							$ 400,000	$ 400,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares				4,700,000			4,700,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized				$ 100,000			$ 100,000
Proceeds from Stock Plans							$ 1,300,000	1,100,000
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | shares										5,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares				3,900,000			3,900,000
2015 MPSUs [Member] | Second, Third, and Fourth Tranches [Member]
Number of Performance Condition to Meet			1
Number of Price Targets			5
Total number of performance conditions			6
2015 MPSUs [Member] | Share-based Compensation Award, Tranche One [Member] | Minimum [Member]
Market Awards Price Targets			$ 71.36
2015 MPSUs [Member] | Share-based Compensation Award, Tranche One [Member] | Maximum [Member]
Market Awards Price Targets			$ 95.57
2015 MPSUs [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Maximum Stock Compensation Costs							$ 8,300,000
Number of Price Targets			5
2015 MPSUs [Member] | Share-based Compensation Award, Tranche Two [Member]
Maximum Stock Compensation Costs							4,500,000
2015 MPSUs [Member] | Share-based Compensation Award, Tranche Three [Member]
Maximum Stock Compensation Costs							5,200,000
2015 MPSUs [Member] | Tranche Four [Member]
Maximum Stock Compensation Costs							$ 6,600,000
2015 MPSUs [Member] | Second and Third Tranches [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
2015 MPSUs [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period | shares	13,000
2015 MPSUs [Member]
Share Price | $ / shares			$ 61.35						$ 61.35
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares			127,000
PSUs Maximum Earn-Out			500.00%
Maximum Stock Compensation Costs							$ 24,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate									33.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate									1.30%
Number of MPSU Tranches			4
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions									7.80%
Restricted Stock Units (RSUs) [Member] | Chief Financial Officer [Member] | Selling, General and Administrative Expenses [Member]
Share-based Compensation Adjustment					$ 2,900,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested				$ 13,500,000		$ 8,400,000	42,600,000	33,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding				$ 296,100,000			$ 296,100,000
Share Price | $ / shares				$ 68.32			$ 68.32
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized				$ 105,800,000			$ 105,800,000
Time-Based RSUs [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							1 year
Time-Based RSUs [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Time-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares							116,000
2016 Executive PSUs [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period | shares	32,000
2016 Executive PSUs [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares		285,000
PSUs Maximum Earn-Out		300.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
Maximum Stock Compensation Costs		$ 30,000,000
2016 Non-Executive PSUs [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares		64,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
Maximum Stock Compensation Costs		$ 6,200,000
PSUs Maximum Earn-Out, Second Tier		200.00%
PSUs Maximum Earn-Out, First Tier		300.00%
2016 Executive PSUs and 2016 Non-executive PSUs [Member]
Share Price | $ / shares		$ 58.98
Purchase Price Per Share | $ / shares		$ 20
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term		2 years 219 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		31.10%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		0.90%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares				34,000			34,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares				$ 15.68			$ 15.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term							1 year 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value				$ 1,800,000			$ 1,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares							1,369,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value				$ 1,400,000		$ 12,900,000	$ 2,500,000	15,400,000
Proceeds from Stock Options Exercised							1,040,000	6,680,000
Proceeds from Stock Plans							$ 1,285,000	$ 1,121,000

Note 2 - Stock Based Compensati

Note 2 - Stock Based Compensation Plan Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cost of Sales [Member]
Share based compensation expense	$ 380	$ 284	$ 814	$ 526
Research and Development Expense [Member]
Share based compensation expense	3,318	2,503	7,016	5,123
Selling, General and Administrative Expenses [Member]
Share based compensation expense	8,049	6,710	12,896	13,067
Share based compensation expense	$ 11,747	$ 9,497	$ 20,726	$ 18,716

Note 2 - RSU Summary (Details)

Note 2 - RSU Summary (Details)	6 Months Ended
	Jun. 30, 2016$ / sharesshares
Time-Based RSUs [Member]
Shares (in shares) | shares	499,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 40.75
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	116,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 61.45
Shares (in shares) | shares	(142,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 33.69
Shares (in shares) | shares	(18,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 42.92
Shares (in shares) | shares	455,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 48.18
PSUs and MPSUs [Member]
Shares (in shares) | shares	1,933,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 38.99
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	1,253,000	[1]
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 40.77
Shares (in shares) | shares	(234,000)	[2]
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 41.14
Shares (in shares) | shares	(563,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 30.07
Shares (in shares) | shares	(129,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 36.82
Shares (in shares) | shares	2,260,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 42.10
MSUs [Member]
Shares (in shares) | shares	1,800,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 23.57
Shares (in shares) | shares	(180,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 23.57
Shares (in shares) | shares	1,620,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 23.57
Shares (in shares) | shares	4,232,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 32.64
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	1,369,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 42.52
Shares (in shares) | shares	(234,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 41.14
Shares (in shares) | shares	(705,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 30.80
Shares (in shares) | shares	(327,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 29.87
Shares (in shares) | shares	4,335,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share) | $ / shares	$ 35.81
[1]	Amount reflects the maximum number of PSUs and MPSUs that can be earned assuming the achievement of the highest level of performance conditions
[2]	Amount reflects the number of PSUs and MPSUs that have not been earned or may not be earned based on management's probability assessment at each reporting period.

Note 2 - Valuation Assumptions

Note 2 - Valuation Assumptions (Details) - 2004 Employee Stock Plan [Member] - Employee Stock Purchase Plan [Member]	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	182 days	182 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	29.70%	35.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.40%	0.10%
Dividend yield	1.40%	1.20%

Note 3 - Inventories (Details)

Note 3 - Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Raw materials	$ 14,423	$ 14,907
Work in process	21,640	21,177
Finished goods	33,856	27,125
Total	$ 69,919	$ 63,209

Note 3 - Other Long-term Assets

Note 3 - Other Long-term Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Deferred compensation plan assets	$ 16,217	$ 13,985
Prepaid wafer purchase	10,000
Other prepaid expense	1,282	1,257
Other	1,199	1,099
Total	$ 28,698	$ 16,341

Note 3 - Accrued Liabilities (D

Note 3 - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Dividends and dividend equivalents	$ 8,852	$ 8,675
Deferred revenue and customer prepayments	4,916	5,236
Stock rotation reserve	1,641	2,372
Warranty	950	289
Commissions	846	763
Sales rebate	221	268
Income tax payable	124	465
Other	1,305	1,916
Total	$ 18,855	$ 19,984

Note 3 - Roll-forward of the Wa

Note 3 - Roll-forward of the Warranty Reserve (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Balance	$ 336	$ 296	$ 289	$ 240
Warranty provision for product sales	734	81	819	155
Settlement made	(42)	(154)	(42)	(154)
Unused warranty provision	(78)	(18)	(116)	(36)
Balance	$ 950	$ 205	$ 950	$ 205

Note 3 - Long-term Liabilities

Note 3 - Long-term Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Deferred compensation plan liabilities	$ 15,395	$ 14,147
Dividend equivalents	2,539	2,019
Other	128	379
Total	$ 18,062	$ 16,545

Note 4 - Goodwill and Acquisi43

Note 4 - Goodwill and Acquisition-related Intangible Assets, Net (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cost Of Revenue [Member]
Amortization of Intangible Assets	$ 500,000	$ 400,000	$ 1,000,000	$ 700,000
Goodwill, Period Increase (Decrease)	$ 0		$ 0

Note 4 - Acquisition-Related In

Note 4 - Acquisition-Related Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Know-How [Member]
Gross Amount	$ 1,018	$ 1,018
Accumulated Amortization	(399)	(297)
Net Amount	619	721
Developed Technology Rights [Member]
Gross Amount	6,466	6,466
Accumulated Amortization	(3,058)	(2,134)
Net Amount	3,408	4,332
Gross Amount	7,484	7,484
Accumulated Amortization	(3,457)	(2,431)
Net Amount	$ 4,027	$ 5,053

Note 4 - Future Amortization Ex

Note 4 - Future Amortization Expense (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
2016 (remaining six months)	$ 1,025
2,017	2,051
2,018	841
2,019	110
Total	$ 4,027	$ 5,053

Note 5 - Net Income Per Share B

Note 5 - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income	$ 11,198	$ 7,899	$ 21,773	$ 13,862
Denominator:
Weighted-average outstanding shares used to compute basic net income per share (in shares)	40,387	39,570	40,208	39,337
Effect of dilutive securities (in shares)	1,329	1,175	1,473	1,333
Weighted-average outstanding shares used to compute diluted net income per share (in shares)	41,716	40,745	41,681	40,670
Basic (in dollars per share)	$ 0.28	$ 0.20	$ 0.54	$ 0.35
Diluted (in dollars per share)	$ 0.27	$ 0.19	$ 0.52	$ 0.34

Note 6 - Segment and Geograph47

Note 6 - Segment and Geographic Information (Details Textual)	6 Months Ended
	Jun. 30, 2016
Number of Reportable Segments	1

Note 6 - Customers with Sales G

Note 6 - Customers with Sales Greater than 10% (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Distributor A [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Distributor A	24.00%	23.00%	22.00%	24.00%

Note 6 - Customers with Account

Note 6 - Customers with Accounts Receivable Greater than 10% (Details) - Accounts Receivable [Member] - Customer Concentration Risk [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Distributor A [Member]
Distributor	27.00%	28.00%
Distributor B [Member]
Distributor	11.00%	17.00%

Note 6 - Revenue by Region (Det

Note 6 - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
CHINA
Region	$ 60,928	$ 53,450	$ 113,316	$ 99,252
TAIWAN, PROVINCE OF CHINA
Region	10,160	10,143	19,015	21,172
Europe [Member]
Region	7,054	5,317	14,039	10,432
KOREA, REPUBLIC OF
Region	7,024	5,109	14,117	9,354
South East Asia [Member]
Region	3,501	3,336	7,840	7,075
JAPAN
Region	3,037	2,412	5,687	4,297
UNITED STATES
Region	2,303	1,566	4,449	3,259
Other Region [Member]
Region	72	83	128	113
Region	$ 94,079	$ 81,416	$ 178,591	$ 154,954

Note 6 - Revenue by Product Fam

Note 6 - Revenue by Product Family (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
DC To DC Products [Member]
Product family	$ 84,221	$ 73,195	$ 161,339	$ 139,492
Lighting Control Products [Member]
Product family	9,858	8,221	17,252	15,462
Product family	$ 94,079	$ 81,416	$ 178,591	$ 154,954

Note 6 - Long Lived Assets by G

Note 6 - Long Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
CHINA
Long lived assets by region	$ 49,959	$ 40,738
UNITED STATES
Long lived assets by region	41,983	40,405
BERMUDA
Long lived assets by region	20,598	11,624
Other Region [Member]
Long lived assets by region	1,049	557
Long lived assets by region	$ 113,589	$ 93,324

Note 8 - Cash Equivalents, Shor

Note 8 - Cash Equivalents, Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Corporate Debt Securities [Member]
Available-for-sale securities	$ 7,581
Auction Rate Securities [Member]
Available-for-sale securities	5,294	5,361
Cash	54,182	58,217
Money market funds	27,864	31,640
Certificates of deposit	7,525	21,574
U.S. treasuries and government agency bonds	146,712	123,532
Total	249,158	240,324
Cash and cash equivalents	82,046	90,860	$ 80,868	$ 126,266
Short-term investments	161,818	144,103
Long-term investments	$ 5,294	$ 5,361

Note 8 - Investment Maturity Cl

Note 8 - Investment Maturity Classification (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Due in less than 1 year	$ 131,926	$ 110,898
Due in 1 - 5 years	29,892	33,205
Due in greater than 5 years	5,294	5,361
Total	$ 167,112	$ 149,464

Note 8 - Unrealized Gains and L

Note 8 - Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Money Market Funds [Member]
Adjusted Cost	$ 27,864	$ 31,640
Total Fair Value	27,864	31,640
Certificates of Deposit [Member]
Adjusted Cost	7,525	21,574
Total Fair Value	7,525	21,574
Corporate Debt Securities [Member]
Adjusted Cost	7,570
Total Fair Value	7,581
Unrealized Gains	11
US Government Agencies Short-term Debt Securities [Member]
Adjusted Cost	146,619	123,698
Total Fair Value	146,712	123,532
Unrealized Gains	97	4
Unrealized Losses	(4)	(170)
Fair Value of Investments in Unrealized Loss Position	16,002	110,720
Auction Rate Securities [Member]
Adjusted Cost	5,570	5,570
Total Fair Value	5,294	5,361
Unrealized Losses	(276)	(209)
Fair Value of Investments in Unrealized Loss Position	5,294	5,361
Adjusted Cost	195,148	182,482
Total Fair Value	194,976	182,107
Unrealized Gains	108	4
Unrealized Losses	(280)	(379)
Fair Value of Investments in Unrealized Loss Position	$ 21,296	$ 116,081

Note 9 - Financial Assets and L

Note 9 - Financial Assets and Liabilities, Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	$ 27,864	$ 31,640
Money Market Funds [Member]
Total Fair Value	27,864	31,640
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	7,525	21,574
Certificates of Deposit [Member]
Total Fair Value	7,525	21,574
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	7,581
Corporate Debt Securities [Member]
Total Fair Value	7,581
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	146,712	123,532
US Government Agencies Short-term Debt Securities [Member]
Total Fair Value	146,712	123,532
Auction Rate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	5,294	5,361
Auction Rate Securities [Member]
Total Fair Value	5,294	5,361
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	10,162	8,279
Mutual Fund [Member]
Total Fair Value	10,162	8,279
Fair Value, Inputs, Level 1 [Member]
Total Fair Value	38,026	39,919
Fair Value, Inputs, Level 2 [Member]
Total Fair Value	161,818	145,106
Fair Value, Inputs, Level 3 [Member]
Total Fair Value	5,294	5,361
Total Fair Value	194,976	182,107
Total Fair Value	$ 205,138	$ 190,386

Note 9 - Level 3 Investments (D

Note 9 - Level 3 Investments (Details) - Auction Rate Securities [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Balance, auction rate securities	$ 5,361
Change in unrealized loss included in other comprehensive income	(67)
Balance, auction rate securities	$ 5,294

Note 9 - Discounted Cash Flow A

Note 9 - Discounted Cash Flow Assumptions (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Minimum [Member]
Expected return	4.20%	4.30%
Maximum [Member]
Expected return	7.20%	7.30%
Time-to-liquidity (months)	2 years	2 years
Expected return	2.10%	2.90%

Note 10 - Summary of Deferred C

Note 10 - Summary of Deferred Compensation Plan (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Other Long-term Assets [Member]
Deferred compensation plan assets reported in:
Other long-term assets	$ 16,217	$ 13,985
Accrued Compensation and Related Benefits [Member]
Deferred compensation plan liabilities reported in:
Deferred compensation plan liabilities	952
Other Long-term Liabilities [Member]
Deferred compensation plan liabilities reported in:
Deferred compensation plan liabilities	15,395	14,147
Other long-term assets	16,217	13,985
Deferred compensation plan liabilities	$ 16,347	$ 14,147

Note 11 - Income Taxes (Details

Note 11 - Income Taxes (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Internal Revenue Service (IRS) [Member] | Domestic Tax Authority [Member]
Income Tax Examination, Year under Examination	2,014
Income Tax Expense (Benefit)		$ 926	$ 2,447	$ 1,270	$ 2,983
Effective Income Tax Rate Reconciliation, Percent		7.60%	23.70%	5.50%	17.70%
Tax Adjustments, Settlements, and Unusual Provisions			$ 2,700
Unrecognized Tax Benefits		$ 14,000		$ 14,000		$ 12,100
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		3,800		3,800		2,700
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		$ 300		$ 300		$ 200

Note 12 - Changes in Accumulate

Note 12 - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Auction Rate Securities [Member]
Balance	$ (217)	$ (209)		$ (209)
Other comprehensive income (loss) before reclassifications	(59)	(8)
Net current period other comprehensive income (loss)	(59)	(8)
Balance	(276)	(217)		(276)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Available-for-sale Securities [Member]
Balance	52	(166)		(166)
Other comprehensive income (loss) before reclassifications	53	220
Amounts reclassified from accumulated other comprehensive income	(1)	(2)
Net current period other comprehensive income (loss)	52	218
Balance	104	52		104
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	2,339	1,841		1,841
Other comprehensive income (loss) before reclassifications	(2,039)	498
Net current period other comprehensive income (loss)	(2,039)	498
Balance	300	2,339		300
Balance	2,174	1,466		1,466
Other comprehensive income (loss) before reclassifications	(2,045)	710
Amounts reclassified from accumulated other comprehensive income	(1)	(2)
Net current period other comprehensive income (loss)	(2,046)	708	$ 90	(1,338)	$ 375
Balance	$ 128	$ 2,174		$ 128

Note 13 - Stock Repurchase (Det

Note 13 - Stock Repurchase (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Feb. 29, 2016	Dec. 31, 2015	Jul. 31, 2013
Stock Repurchased and Retired During Period, Shares	0	100,000	0	400,000
Stock Repurchase Program, Authorized Amount					$ 50		$ 100
Stock Repurchase Program, Remaining Authorized Repurchase Amount						$ 5.9
Stock Repurchased and Retired During Period, Value		$ 7.7		$ 18.1
Repurchase Stock, Average Price Per Share, During Period		$ 52.19		$ 51.70

Note 14 - Dividends and Divid63

Note 14 - Dividends and Dividend Equivalents (Details Textual) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Dividends Payable, Current	$ 8.1	$ 7.9
Dividend Equivalents, Current	$ 3.3	$ 2.8

Note 14 - Cash Dividends (Detai

Note 14 - Cash Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015
Dividend declared per share (in dollars per share)	$ 0.20	$ 0.20	$ 0.20	$ 0.20
Total amount	$ 8,096	$ 8,047	$ 7,925	$ 7,854

Note 15 - Subsequent Event (Det

Note 15 - Subsequent Event (Details Textual) - shares	1 Months Ended	6 Months Ended
	Jul. 29, 2016	Jun. 30, 2016
Chief Financial Officer [Member] | Subsequent Event [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	12,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		1,369,000