Alpha and Omega Semiconductor Limited (AOSL) 10-Q 7 Feb 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Dec. 31, 2018	Jan. 31, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	ALPHA & OMEGA SEMICONDUCTOR Ltd
Entity Central Index Key	1,387,467
Current Fiscal Year End Date	--06-30
Entity Filer Category	Smaller Reporting Accelerated Filer
Document Type	10-Q
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		23,940,455

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Current assets:
Cash and cash equivalents	$ 146,632	$ 131,535
Restricted cash	255	189
Accounts receivable, net	33,858	33,755
Inventories	102,962	90,182
Other current assets	34,271	29,551
Total current assets	317,978	285,212
Property, plant and equipment, net	380,783	331,656
Intangible assets, net	16,939	16,591
Deferred income tax assets	4,944	4,892
Other long-term assets	13,544	28,698
Total assets	734,188	667,049
Current liabilities:
Accounts payable	102,617	92,661
Accrued liabilities	59,013	49,841
Income taxes payable	1,769	2,211
Short term debt	22,797	3,811
Deferred margin	0	1,665
Capital leases	7,429	4,491
Total current liabilities	193,625	154,680
Long-term debts	36,729	26,786
Income taxes payable - long-term	951	924
Deferred income tax liabilities	1,134	713
Capital leases - long-term	51,185	56,791
Other long-term liabilities	6,036	993
Total liabilities	289,660	240,887
Commitments and contingencies (Note 11)
Preferred shares, par value $0.002 per share:
Authorized: 10,000 shares, issued and outstanding: none at December 31, 2018 and June 30, 2018	0	0
Common shares, par value $0.002 per share:
Authorized: 100,000 shares, issued and outstanding: 30,590 shares and 23,939 shares, respectively at December 31, 2018 and 30,400 shares and 23,860 shares, respectively at June 30, 2018	61	61
Treasury shares at cost, 6,651 shares at December 31, 2018 and 6,540 shares at June 30, 2018	(66,283)	(64,790)
Additional paid-in capital	227,818	220,244
Accumulated other comprehensive income (loss)	(2,842)	440
Retained earnings	124,538	122,639
Total Alpha and Omega Semiconductor Limited shareholder's equity	283,292	278,594
Noncontrolling interest	161,236	147,568
Total equity	444,528	426,162
Total liabilities and equity	$ 734,188	$ 667,049

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Jun. 30, 2018
Common shares, par value (in dollars per share)	$ 0.002	$ 0.002
Common shares, authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	30,590,000	30,400,000
Common stock, shares outstanding (in shares)	23,939,000	23,860,000
Preferred stock, par value (in dollars per share)	$ 0.002	$ 0.002
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Treasury shares (in shares)	6,651,000	6,540,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 114,925	$ 103,896	$ 229,997	$ 208,754
Cost of goods sold	85,423	75,814	167,884	153,142
Gross profit	29,502	28,082	62,113	55,612
Operating expenses
Research and development	12,600	9,102	23,984	17,427
Selling, general and administrative	20,104	15,756	40,456	30,371
Total operating expenses	32,704	24,858	64,440	47,798
Operating income (loss)	(3,202)	3,224	(2,327)	7,814
Interest income and other income (loss), net	74	(160)	336	(120)
Interest expense	(1,706)	(14)	(3,196)	(31)
Net income (loss) before income taxes	(4,834)	3,050	(5,187)	7,663
Income tax expense (benefit)	701	(2,072)	1,261	(798)
Net income (loss) including noncontrolling interest	(5,535)	5,122	(6,448)	8,461
Net loss attributable to noncontrolling interest	(3,990)	(1,669)	(7,319)	(3,130)
Net income (loss) attributable to Alpha and Omega Semiconductor Limited	$ (1,545)	$ 6,791	$ 871	$ 11,591
Net income (loss) per common share attributable to Alpha and Omega Semiconductor Limited
Basic (in dollars per share)	$ (0.06)	$ 0.28	$ 0.04	$ 0.48
Diluted (in dollars per share)	$ (0.06)	$ 0.27	$ 0.04	$ 0.46
Weighted average number of common shares attributable to Alpha and Omega Semiconductor Limited used to compute net income (loss) per share
Basic (in shares)	23,887	23,925	23,865	23,973
Diluted (in shares)	23,887	25,033	24,513	24,997

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Net income (loss) including noncontrolling interest	$ (5,535)	$ 5,122	$ (6,448)	$ 8,461
Other comprehensive income, net of tax
Foreign currency translation adjustment	(58)	3,347	(6,295)	4,048
Comprehensive income (loss)	(5,593)	8,469	(12,743)	12,509
Noncontrolling interest	(4,014)	(104)	(10,332)	(1,231)
Comprehensive income (loss) attributable to Alpha and Omega Semiconductor Limited	$ (1,579)	$ 8,573	$ (2,411)	$ 13,740

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income (loss) including noncontrolling interest	$ (6,448)	$ 8,461
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	16,149	14,386
Share-based compensation expense	7,547	6,017
Deferred income taxes, net	94	(2,224)
Loss (gain) on disposal of property and equipment	(6)	55
Changes in assets and liabilities:
Accounts receivable, net	(326)	4,127
Inventories	(12,780)	(9,418)
Other current and long-term assets	(696)	(9,081)
Accounts payable	9,927	1,877
Income taxes payable	(415)	(448)
Accrued and other liabilities	18,035	8,102
Net cash provided by operating activities	31,081	21,854
Cash flows from investing activities
Purchases of property and equipment excluding JV Company	(23,218)	(23,192)
Purchases of property and equipment in JV Company	(42,723)	(41,576)
Purchase of intangible assets	(405)	(10,384)
Proceeds from Sale of Other Property, Plant, and Equipment	19	0
Net cash used in investing activities	(66,327)	(75,152)
Cash flows from financing activities
Proceeds from investment by noncontrolling interest	24,000	86,994
Withholding tax on restricted stock units	(203)	(249)
Proceeds from exercise of stock options and ESPP	1,278	2,205
Payment for repurchases of common shares	(1,501)	(6,022)
Proceeds from borrowings	36,191	0
Repayments of borrowings	(7,308)	0
Principal payments on capital leases	(417)	(399)
Net cash provided by financing activities	52,040	82,529
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,631)	1,241
Net increase in cash, cash equivalents and restricted cash	15,163	30,472
Cash, cash equivalents and restricted cash at beginning of period	131,724	115,929
Cash, cash equivalents and restricted cash at end of period	146,887	146,401
Supplemental disclosures of non-cash investing and financing information:
Property and equipment purchased but not yet paid	61,573	43,235
Re-issuance of treasury stock	$ 8	$ 3

The Company and Significant Acc

The Company and Significant Accounting Policies	6 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company and Significant Accounting Policies	The Company and Significant Accounting Policies The Company Alpha and Omega Semiconductor Limited and its subsidiaries (the “Company”, "AOS", "we" or "us") design, develop and supply a broad range of power semiconductors. The Company's portfolio of products targets high-volume applications, including personal computers, flat panel TVs, LED lighting, smart phones, battery packs, quick chargers, home appliances, consumer and industrial motor controls and power supplies for TVs, computers, servers and telecommunications equipment. The Company conducts its operations primarily in the United States of America (“USA”), Hong Kong, China, and South Korea. Basis of Preparation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and with the instructions to Article 10 of Securities and Exchange Commission Regulation S-X, as amended. They do not include all information and footnotes necessary for a fair presentation of financial position, results of operations and cash flows in conformity with U.S. GAAP for complete financial statements. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018 . All significant intercompany balances and transactions have been eliminated in consolidation. In the opinion of management, all adjustments (consisting of normal recurring adjustments and accruals) considered necessary for a fair presentation of the results of operations for the periods presented have been included in the interim periods. Operating results for the six months ended December 31, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending June 30, 2019 . The condensed consolidated balance sheet at June 30, 2018 is derived from the audited financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018 . Joint Venture In March 2016, the Company executed an agreement with two strategic investment funds owned by the Municipality of Chongqing, China (the "Chongqing Funds") to form a joint venture, (the "JV Company"), for a new state-of-the-art power semiconductor packaging, testing and wafer fabrication facility in Liangjiang New Area of Chongqing (the "Joint Venture"). The initial capitalization of the Joint Venture under the agreement was $330.0 million , which includes cash contributions from the Chongqing Funds and contributions of cash, equipment and intangible assets from the Company. In August 2018, the Company invested an additional $25.0 million of cash contribution to the JV Company, which resulted in the Company owned 54.4% , and the Chongqing Funds owned 45.6% , of the equity interest in the JV Company. At the end of December 2018, the Chongqing Funds invested additional $24.0 million of cash contribution to the JV Company, which resulted in the Company owning 50.9% , and the Chongqing Funds owning 49.1% , of the equity interest in the JV Company. The Joint Venture is accounted for under the provisions of the consolidation guidance since the Company has a controlling financial interest. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires the Company to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses. To the extent there are material differences between these estimates and actual results, the Company's condensed consolidated financial statements will be affected. On an ongoing basis, the Company evaluates the estimates, judgments and assumptions including those related to stock rotation returns, price adjustments, allowance for doubtful accounts, inventory reserves, warranty accrual, income taxes, share-based compensation, and useful lives for property, plant and equipment and intangible assets. Share-based Compensation Expense The Company recognizes expense related to share-based compensation awards that are ultimately expected to vest based on estimated fair values on the date of grant. The fair value of restricted share units is based on the market value of the Company's common share on the date of grant. For restricted stock awards subject to market conditions, the fair value of each restricted stock award is estimated at the date of grant using the Monte-Carlo pricing model. The fair value of stock options is estimated on the date of grant using the Black-Scholes option valuation model. Share-based compensation expense is recognized on the accelerated attribution basis, net of estimated forfeitures, over the requisite service period of the award, which generally equals the vesting period. Fair Value of Financial Instruments The fair value of cash equivalents is based on observable market prices and have been categorized in Level 1 in the fair value hierarchy. Cash equivalents consist primarily of short term bank deposits. The carrying values of financial instruments such as cash and cash equivalents, accounts receivable and accounts payable approximate their carrying values due to their short-term maturities. The carrying value of the company's debt is considered a reasonable estimate of fair value which is estimated by considering the current rates available to the Company for debt of the same remaining maturities, structure and terms of the debts. Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. The Company's accumulated other comprehensive income (loss) consists of cumulative foreign currency translation adjustments. Total comprehensive income (loss) is presented in the condensed consolidated statements of comprehensive income (loss). Recent Accounting Pronouncements Recently Issued Accounting Standards not yet adopted In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should be presented in the form of a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed with the SEC. The Company's first presentation of changes in stockholders' equity will be included in its Form 10-Q for the quarter ending March 31, 2019. In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-15 “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15”). These amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contact with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by these amendments. ASU 2018-15 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. The Company is currently assessing the impact that adoption of this guidance will have on its consolidated financial statements. In August 2018, the FASB issued Accounting Standard Updates ("ASU") ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement ("ASU 2018-13”). ASU 2018-13 amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. ASU No. 2018-13 is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2019. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial position, results of operations or cash flows. In June 2018, the FASB issued ASU 2018-07, "Compensation -Stock Compensation: Improvement to Nonemployees Share-Based Payment Accounting ("ASU 2018-07"), which expands the scope of Topic 718 to include all share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-07 specifies that Topic 718 applies to all share-based payment transactions in which the grantor acquires goods and services to be used or consumed in its own operations by issuing share-based payment awards. ASU 2018-07 also clarifies that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under ASC 606. ASU 2018-07 is effective fiscal years beginning after December 15, 2018, including interim periods within that fiscal year, with early adoption permitted, but no earlier than our adoption of ASC 606. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial position, results of operations or cash flows. In February 2016, the FASB issued ASU 2016-02, Leases. This guidance requires a dual approach for lessee accounting under which a lessee will account for leases as finance leases or operating leases. Both finance and operating leases will result in the lessee recognizing a right-of-use asset and a corresponding liability on its balance sheet, with differing methodology for income statement recognition. This guidance is effective for public business entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. A modified retrospective approach is required for all leases existing or entered into after the beginning of the earliest comparative period in the consolidated financial statements. In July 2018, the FASB issued ASU 2018-11, “Leases (Topic 842): Targeted Improvements.”, which permits an entity to elect an additional transition method to the existing modified retrospective transition requirements. Under the new transition method, an entity could adopt the provisions of ASU No. 2016-02 by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption without adjustment to the financial statements for periods prior to adoption. Consequently, an entity’s reporting for the comparative periods presented in the financial statements in which it adopts the new leases standard will continue to be in accordance with the previous lease guidance in ASC Topic 840. ASU 2018-11 also allows a practical expedient that permits lessors to not separate non-lease components from the associated lease component if certain conditions are present. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from previous Generally Accepted Accounting Principles. Although the Company is currently evaluating the impact the pronouncement will have on its consolidated financial statements and related disclosures, the Company expects that most of its operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon adoption. Recently Adopted Accounting Standards In May 2017, the FASB issued ASU 2017-09, "Compensation -Stock Compensation: Scope of Modification Accounting ("ASU 2017-09"). ASU 2017-09 is an update to the existing guidance to clarify when modification accounting would be applied for a change to the terms or conditions of a share-based award. Under this new guidance, modification accounting is required only if the fair value, a vesting condition, or the classification of the award changes as a result of the change in terms or conditions. This ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017 with early adoption permitted. The Company does not regularly modify the terms and conditions of its share-based awards and the adoption of this guidance has no impact on its financial statements. In November 2016, the FASB issued ASU 2016-18, "Statement of Cash Flows: Restricted Cash ("ASU 2016-18"). ASU 2016-18 requires amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the total beginning and ending amounts for the periods shown on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted and requires retrospective adoption. The Company adopted this standard effective July 1, 2018. The reclassified restricted cash balances from investing activities to changes in cash, cash equivalents and restricted cash on the condensed consolidated statements of cash flows were not material for all periods presented. In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"). ASU 2016-15 identifies how certain cash receipts and cash payments are presented and classified in the Statement of Cash Flows under Topic 230. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. Upon adoption, entities must apply the guidance retrospectively to all periods presented. There was no impact on the Company's consolidated financial statements upon the adoption of this standard. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606). The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The core principle of the model is to recognize revenue when control of the goods or services transfers to the customer, as opposed to recognizing revenue when the risks and rewards transfer to the customer under the existing revenue guidance. The change for the Company under ASC 606 relates to the timing of revenue recognition with two U.S.-based distributors. Sales to these distributors are governed under the terms of agreements providing extended price protection and other return rights, and were historically deferred under the previous accounting guidance until the related product was sold to the end customer. Under ASC 606, the transaction price takes into consideration the effect of variable consideration such as price adjustments and returns rights, which are estimated and recorded at the time the goods are delivered. Accordingly, the Company recognizes revenue under ASC 606 at the time of shipment or delivery to these two distributors, adjusted for estimates of the price adjustments and product returns based on historical data and other available information. Revenue from other non-U.S. distributors and direct customers, which consists of the majority of the Company's total revenue, is recognized at the time of shipment or delivery to the distributors and direct customers. Accordingly, revenue recognition with these distributors and direct customers remains unchanged upon adoption of ASC 606. See "Note 2 - Revenue" for additional information on the impact of the adoption of the new standard on the Company’s consolidated financial statements.

Revenue (Notes)

Revenue (Notes)	6 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Impact from the Adoption of the New Revenue Standard: On July 1, 2018, the Company adopted ASC 606 using the modified retrospective method applied to all contracts. Results for reporting periods beginning after July 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under ASC 605. The change for the Company under ASC 606 relates to the timing of revenue recognition with two U.S.-based distributors. Sales to these distributors are governed under the terms of agreements providing extended price protection and other return rights. The Company recorded a net increase to opening retained earnings of $1.0 million as of July 1, 2018 due to the cumulative impact of adopting ASC 606, with a corresponding $1.6 million decrease in deferred margin, a $0.2 million decrease in accounts receivables, a $0.1 million increase in current accrued liabilities, and a $0.3 million increase in deferred tax liabilities. Effective July 1, 2018, the Company recognized revenue at the time of shipment or delivery to these two distributors, adjusted for estimates of the price adjustments and return rights based on historical data and other available information. Based on the Company's assessment, only minimal changes were required to the Company's existing policies, processes, and controls to support the standard's measurement and disclosure requirements. The following tables compare the amounts reported in the condensed consolidated statements of income and condensed consolidated balance sheet to the amounts had the previous revenue recognition guidance been in effect: As of December 31, 2018 As Reported Adjustment Balances Without Adoption (in thousands) Accounts receivable, net $ 33,858 $ 193 $ 34,051 Accrued liabilities $ 59,013 $ (84 ) $ 58,929 Deferred margin $ — $ 1,782 $ 1,782 Income taxes payable $ 1,769 $ (45 ) $ 1,724 Deferred income tax liabilities $ 1,134 $ (313 ) $ 821 Retained earnings $ 124,538 $ (1,183 ) $ 123,355 Three Months Ended December 31, 2018 Six Months Ended December 31, 2018 As Reported Adjustment Balances Without Adoption As Reported Adjustment Balances Without Adoption (in thousands) (in thousands) Revenue $ 114,925 $ (349 ) $ 114,576 $ 229,997 $ (308 ) $ 229,689 Cost of goods sold $ 85,423 $ (134 ) $ 85,289 $ 167,884 $ (114 ) $ 167,770 Gross profit $ 29,502 $ (215 ) $ 29,287 $ 62,113 $ (194 ) $ 61,919 Income tax expense (benefit) $ 701 $ (37 ) $ 664 $ 1,261 $ (45 ) $ 1,216 Net loss including noncontrolling interest $ (5,535 ) $ (178 ) $ (5,713 ) (6,448 ) $ (149 ) $ (6,597 ) New Revenue Recognition Policy Including Significant Judgments and Estimates As a result of the adoption of the new revenue standard on July 1, 2018, at the beginning of the first quarter of fiscal year 2019, the Company determines revenue recognition through the following steps: (1) identification of the contract with a customer; (2) identification of the performance obligations in the contract; (3) determination of the transaction price; (4) allocation of the transaction price to the performance obligations in the contract; and (5) recognition of revenue when, or as, a performance obligation is satisfied. The Company has written contracts with combination of agreements and purchase orders with all customers including certain general terms and conditions. Often purchase orders entail merchandises, quantities and prices, which define the performance obligations of each party and are approved or accepted by the Company. The Company’s contracts with customers do not typically include extended payment terms. Payment terms vary by contract type and type of customer and generally range from 30 to 60 days. The Company’s performance obligations are to deliver the requested goods or services to customers according to the agreed shipping terms. As such, there is no material difference in regards to performance obligations vs. “deliverables” under ASC 606 vs. the legacy revenue guidance. The Company recognizes revenue when the performance obligation is satisfied. The majority of the Company’s total revenue is from non-U.S. distributors and direct customers, which is recognized at the time of shipment or delivery to distributors and direct customers. Accordingly, revenue recognition with these distributors and direct customers remains unchanged upon adoption of ASC 606. As noted above, the change for the Company under ASC 606 relates to the timing of revenue recognition with two U.S.-based distributors. Sales to these distributors are governed under the terms of agreements providing extended price protection and other return rights, and were historically deferred under the previous accounting guidance until the related product was sold to end customers. Under ASC 606, the transaction price takes into consideration the effect of variable consideration such as price adjustments and return rights, which are estimated and recorded at the time the goods are delivered. Because all of the Company’s performance obligations relate to contracts with a duration of less than one year, the Company elected to apply the optional exemption practical expedient provided in ASC 606 and, therefore, is not required to disclose the aggregate amount of the transaction price allocated to performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period. The Company adjusts the transaction price for variable consideration. Variable consideration primarily are adjustments related to stock rotation rights and price adjustments provided to our distributors. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract, specifically commission expenses that have a period of benefit of less than twelve months, as an expense when incurred. Additionally, the Company has adopted an accounting policy to recognize shipping costs that occur after control transfers to the customer as a fulfillment activity. The Company warrants its products to be free of defects generally for a period of one year. The Company estimates its warranty costs based on historical warranty claim experience and includes such costs in cost of goods sold. Warranty expenses and the accrued warranty liability were not material as of December 31, 2018. The following table presents the Company's revenue information by geographical location based on the country or region to which the products were shipped. The Company sells its products primarily to distributors in the Asia Pacific region, who in turn sell these products to end customers. Because the Company's distributors sell their products to end customers which may have a global presence, revenue by geographical location is not necessarily representative of the geographical distribution of sales to end user markets. Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Hong Kong $ 87,180 $ 82,440 $ 178,771 $ 167,670 China 24,760 19,153 45,157 36,273 South Korea 139 301 308 588 United States 1,967 1,314 3,940 2,692 Other countries 879 688 1,821 1,531 $ 114,925 $ 103,896 $ 229,997 $ 208,754 The following is a summary of revenue by product type: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Power discrete $ 93,294 $ 85,094 $ 185,549 $ 168,772 Power IC 19,384 15,758 38,799 33,855 Packaging and testing services 2,247 3,044 5,649 6,127 $ 114,925 $ 103,896 $ 229,997 $ 208,754

Net Income (Loss) Per Share

Net Income (Loss) Per Share	6 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) Per Common Share Attributable to Alpha and Omega Semiconductor Limited The following table presents the calculation of basic and diluted net income (loss) per share attributable to common shareholders: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands, except per share data) Numerator: Net income (loss) attributable to Alpha and Omega Semiconductor Limited $ (1,545 ) $ 6,791 $ 871 $ 11,591 Denominator: Basic: Weighted average number of common shares used to compute basic net income (loss) per share 23,887 23,925 23,865 23,973 Diluted: Weighted average number of common shares used to compute basic net income per share 23,887 23,925 23,865 23,973 Effect of potentially dilutive securities: Stock options, RSUs and ESPP shares — 1,108 648 1,024 Weighted average number of common shares used to compute diluted net income per share 23,887 25,033 24,513 24,997 Net income (loss) per share attributable to Alpha and Omega Semiconductor Limited: Basic $ (0.06 ) $ 0.28 $ 0.04 $ 0.48 Diluted $ (0.06 ) $ 0.27 $ 0.04 $ 0.46 The following potential dilutive securities were excluded from the computation of diluted net income per share as their effect would have been anti-dilutive: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Employee stock options and RSUs 2,225 165 646 169 ESPP 1,240 — 508 45 Total potential dilutive securities 3,465 165 1,154 214

Concentration of Credit Risk an

Concentration of Credit Risk and Significant Customers	6 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Concentration of Credit Risk and Significant Customers	Concentration of Credit Risk and Significant Customers The Company manages its credit risk associated with exposure to distributors and direct customers on outstanding accounts receivable through the application and review of credit approvals, credit ratings and other monitoring procedures. In some instances, the Company also obtains letters of credit from certain customers. Credit sales, which are mainly on credit terms of 30 to 60 days , are only made to customers who meet the Company's credit requirements, while sales to new customers or customers with low credit ratings are usually made on an advance payment basis. The Company considers its trade accounts receivable to be of good credit quality because its key distributors and direct customers have long-standing business relationships with the Company and the Company has not experienced any significant write-offs of accounts receivable in the past. The Company closely monitors the aging of accounts receivable from its distributors and direct customers, and regularly reviews their financial positions, when available. Summarized below are individual customers whose revenue or accounts receivable balances were more than 10% of the respective total consolidated amounts: Three Months Ended December 31, Six Months Ended December 31, Percentage of revenue 2018 2017 2018 2017 Customer A 30.6 % 30.8 % 29.1 % 29.2 % Customer B 37.6 % 33.7 % 37.8 % 33.8 % December 31, June 30, Percentage of accounts receivable Customer A 25.0 % 17.1 % Customer B 35.1 % 35.5 % Customer C * 10.6 % * Less than 10%

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Balance Sheet Components Accounts receivable, net: December 31, June 30, (in thousands) Accounts receivable $ 52,465 $ 52,687 Less: Allowance for price adjustments (18,577 ) (18,902 ) Less: Allowance for doubtful accounts (30 ) (30 ) Accounts receivable, net $ 33,858 $ 33,755 Inventories: December 31, June 30, (in thousands) Raw materials $ 54,188 $ 47,097 Work in-process 39,307 35,243 Finished goods 9,467 7,842 $ 102,962 $ 90,182 Other current assets: December 31, June 30, (in thousands) VAT receivable $ 28,305 $ 17,601 Other prepaid expenses 2,603 2,121 Prepaid insurance 538 906 Prepaid maintenance 693 556 Prepayment to supplier 535 227 Prepaid income tax 747 761 Custom deposit 55 5,749 Lease financing cost 655 960 Other receivable 140 670 $ 34,271 $ 29,551 Property, plant and equipment, net: December 31, June 30, (in thousands) Land $ 4,877 $ 4,877 Building 33,884 4,325 Manufacturing machinery and equipment 285,078 265,192 Equipment and tooling 19,334 16,605 Computer equipment and software 28,062 25,686 Office furniture and equipment 2,794 2,314 Leasehold improvements 30,920 29,900 Land use rights 8,751 9,089 413,700 357,988 Less: accumulated depreciation (237,620 ) (225,184 ) 176,080 132,804 Equipment and construction in progress 204,703 198,852 Property, plant and equipment, net $ 380,783 $ 331,656 Intangible assets, net: December 31, June 30, (in thousands) Patents and technology rights $ 18,037 $ 17,633 Trade name 268 268 Customer relationships 1,150 1,150 19,455 19,051 Less: accumulated amortization (2,785 ) (2,729 ) 16,670 16,322 Goodwill 269 269 Intangible assets, net $ 16,939 $ 16,591 Intangible assets of patents and technology rights are primarily related to a license agreement that the Company entered into with STMicroelectronics International N.V. (“STMicro”) on September 5, 2017, pursuant to which STMicro granted the Company a world-wide, royalty-free and fully-paid license to use its technologies to develop, market and distribute certain digital multi-phase controller products, which have been offered by STMicro. This agreement allows the Company to develop and market products in a new market for digital power products, primarily in the computer server segment. As of December 31, 2018 , the Company recorded $16.2 million of intangible assets related to STMicro. The Company begins amortizing such license fees when the technology has met the Company's qualification and is ready for its intended use in production. Other long-term assets: December 31, June 30, (in thousands) Prepayments for property and equipment $ 6,222 $ 17,599 Investment in a privately held company 700 700 Lease financing costs 1,650 1,922 VAT long-term receivable 4 3,396 Custom deposit 1,701 1,589 Other long-term deposits 1,812 2,252 Office leases deposits 989 853 Other 466 387 $ 13,544 $ 28,698 Accrued liabilities: December 31, June 30, (in thousands) Accrued compensation and benefits $ 29,694 $ 18,484 Warranty accrual 655 535 Stock rotation accrual 1,847 1,750 Accrued professional fees 1,738 1,922 Accrued inventory 1,340 667 Accrued facilities related expenses 1,879 2,163 Accrued financing lease costs 727 1,510 Accrued property, plant and equipment 13,090 18,145 Other accrued expenses 8,043 4,665 $ 59,013 $ 49,841 The activities in the warranty accrual, included in accrued liabilities, are as follows: Six Months Ended December 31, 2018 2017 (in thousands) Beginning balance $ 535 $ 1,866 Additions (reductions) 189 (1,063 ) * Utilization (69 ) (36 ) Ending balance $ 655 $ 767 * Released a specific warranty reserve of approximately $1.0 million due to expired warranty period. The activities in the stock rotation accrual, included in accrued liabilities, are as follows: Six Months Ended December 31, 2018 2017 (in thousands) Beginning balance $ 1,750 $ 1,871 Additions 2,229 992 Utilization (2,132 ) (1,252 ) Ending balance $ 1,847 $ 1,611

Bank Borrowing Bank Borrowing

Bank Borrowing Bank Borrowing	6 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Bank Borrowing	Bank Borrowings Short-term borrowing On November 29 and December 4, 2018, the JV Company entered into two one-year loan agreements with China Merchant Bank in China to provide loans for Chinese Renminbi (RMB) 80 million and 20 million , respectively, or $14.5 million in total based on currency exchange rate between RMB and U.S. Dollars on December 31, 2018 at varying interest rates. Interest payments are due monthly and quarterly with the entire principal due not later than December 18 and December 5, 2019, respectively. As of December 31, 2018 , the outstanding balance under the loans were 80 million RMB and 20 million (equivalent of $14.5 million in total based on the currency exchange rate as of December 31, 2018 ). On November 16, 2018, the Company's subsidiary in China entered into a line of credit facility with Industrial and Commercial Bank of China, which expires on September 30, 2019. The purpose the credit facility is to provide short-term borrowings. The Company can borrow up to approximately RMB 72.0 million or $10.3 million based on currency exchange rate between RMB and U.S. Dollars on November 16, 2018. In November 2018, the Company borrowed $5.0 million under this line with an interest rate of 3.64% per annum. The amount of $5.0 million was repaid in December 2018. Credit Facilities On May 9, 2018 (the “Effective Date”), the JV Company entered into a lease finance agreement and a security agreement (the “Agreements”) with YinHai Leasing Company and China Import/Export Bank (the “Lenders”). Pursuant to the Agreements, the Lenders agree to provide an aggregate of RMB 400.0 million , or $62.8 million based on the currency exchange rate between RMB and U.S. Dollars on the Effective Date, of financing to the JV Company (the “Lease Financing”). In exchange for the Lease Financing, the JV Company agrees to transfer title of its assembly and testing equipment to the Lenders, and the Lenders lease such equipment to the JV Company under a five -year lease arrangement, pursuant to which the JV Company makes quarterly lease payments to the Lenders consisting of principal and interest based on a repayment schedule mutually agreed by the parties. The interest under the Lease Financing is accrued based on the China Base Rate multiplied by 1.15 , or 5.4625% on the Effective Date. Under the Agreements, at the end of the five-year lease term, the Lenders agree to sell such equipment back to the JV Company for a nominal amount (RMB 1 ). The JV Company’s obligations under the Lease Financing are secured by the land and building owned by the JV Company (the “Collateral”). The proceeds from the Lease Financing will be used primarily for the acquisition and installation of the 12-inch fabrication equipment and other expenses of the JV Company relating to the completion of the fabrication facility located in Chongqing. The Agreements contain customary representation, warranties and covenants, including restrictions on the transfer of the Collateral. The Agreements also contain customary events of default, including but are not limited to, failure to make payments and breach of material terms under the Agreements. The Agreements include certain customary closing conditions, including the payment of deposit by the JV Company. As of December 31, 2018 , the outstanding balance under the Agreement was 400 million RMB (equivalent of $58.2 million based on the currency exchange rate as of December 31, 2018 ), which was recorded under short-term and long-term capital lease liabilities. Capital lease liabilities include financing leases, computer software and exclusive technology rights. Future minimum lease payments are as follows (in thousands): Year ending June 30, 2019 (Remaining) $ 5,530 2020 14,203 2021 17,778 2022 16,909 2023 12,255 Total minimum lease payments 66,675 Less amount representing interest (8,061 ) Total capital lease liabilities $ 58,614 On May 1, 2018, Jireh Semiconductor Incorporated ("Jireh"), a wholly-owned subsidiary of the Company, entered into a loan agreement with a financial institution (the "Bank") that provided a term loan in an amount of $17.8 million . The obligation under the loan agreement is secured by certain real estate assets of Jireh and guaranteed by the Company. The loan has a five-year term and matures on June 1, 2023. Beginning June 1, 2018, Jireh made consecutive monthly payments of principal and interest to the Bank. The outstanding principal shall accrue interest at a fixed rate of 5.04% per annum on the basis of a 360-day year. The loan agreement contains customary restrictive covenants and includes certain financial covenants that require the Company to maintain, on a consolidated basis, specified financial ratios. The Company is in compliance with these covenants. As of December 31, 2018 , the outstanding balance of the term loan was $17.3 million . On August 15, 2017, Jireh entered into a credit agreement with the Bank that provided a term loan in an amount up to $30.0 million for the purpose of purchasing certain equipment for the Company's fabrication facility located in Oregon. The obligation under the credit agreement is secured by substantially all assets of Jireh and guaranteed by the Company. The credit agreement has a five -year term and matures on August 15, 2022. In January 2018 and July 2018, Jireh drew down the loan in the amount of $13.2 million and $16.7 million , respectively. Beginning in October 2018, Jireh was required to pay to the Bank on each payment date, the outstanding principal amount of the loan in monthly installments. The loan accrues interest based on an adjusted London Interbank Offered Rate ("LIBOR") as defined in the credit agreement, plus specified applicable margin in the range of 1.75% to 2.25% , based on the outstanding balance of the loan. The credit agreement contains customary restrictive covenants and includes certain financial covenants that require the Company to maintain, on a consolidated basis, specified financial ratios and fixed charge coverage ratio. The Company is in compliance with these covenants. As of December 31, 2018 , the outstanding balances of the term loan were $27.9 million . Maturities of Jireh debt were as follows (in thousands): Year ending June 30, 2019 (Remaining) $ 4,170 2020 8,340 2021 8,340 2022 8,340 2023 16,028 Total principal of debt 45,218 Less: debt issuance costs (233 ) Total principal of debt, less debt issuance costs $ 44,985

Joint Venture

Joint Venture	6 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture	Joint Venture On March 29, 2016, the Company entered into a joint venture contract (the “JV Agreement”) with two investment funds owned by the Municipality of Chongqing (the “Chongqing Funds”), pursuant to which the Company and the Chongqing Funds formed a joint venture, (the “JV Company”), for the purpose of constructing and operating a power semiconductor packaging, testing and 12-inch wafer fabrication facility in the Liangjiang New Area of Chongqing, China (the “JV Transaction”). As of September 30, 2018, the Company owned 54.4% , and the Chongqing Funds owned 45.6% , of the equity interest in the JV Company. At the end of December 2018, the Chongqing Funds invested additional $24.0 million of cash contribution to the JV Company, which resulted in the Company owning 50.9% , and the Chongqing Funds owning 49.1% , of the equity interest in the JV Company. The JV Company commenced small mass production for assembly and testing started the quarter ended September 30, 2018. During the quarter ended December 31, 2018, the JV Company continued the production ramp and commenced trial production at the 12-inch wafer fabrication facility. As part of the JV Transaction, the JV Company entered into an Engineering, Procurement and Construction Contract (the “EPC Contract”) with The IT Electronics Eleventh Design & Research Institute Scientific and Technological Engineering Corporation Limited (the “Contractor”), effective as of January 10, 2017 (the "Effective Date"), pursuant which the Contractor was engaged to construct the manufacturing facility contemplated under the JV Agreement. The total price payable under the EPC Contract is Chinese Renminbi (RMB) 540.0 million, or approximately $78.0 million based on the currency exchange rate between RMB and U.S. Dollars on the Effective Date, which consists of $2.8 million (RMB 19.5 million) of design fees and $75.2 million (RMB 520.5 million) of construction and procurement fees (including compliance with safety and aesthetic requirements). As of December 31, 2018 , the JV Company paid approximately $68.3 million (RMB 470.0 million ), and expects to pay the remaining of $10.2 million (RMB 70.0 million ) in fiscal year 2019. The changes in total AOS shareholders' equity, noncontrolling interest and total equity were as follows (in thousands): Total AOS Shareholders' Equity Noncontrolling Interest Total Equity Balance, June 30, 2018 $ 278,594 $ 147,568 $ 426,162 Exercise of common stock options and release of RSUs 110 — 110 Withholding tax on restricted stock units (203 ) — (203 ) Issuance of shares under ESPP 1,168 — 1,168 Repurchase of common shares under shares repurchase program (1,501 ) — (1,501 ) Share-based compensation expense 6,499 — 6,499 Net income (loss) 871 (7,319 ) (6,448 ) Impact on retained earnings related to ASC 606 adoption 1,036 — 1,036 Cumulative translation adjustment (3,282 ) (3,013 ) (6,295 ) Contributions from noncontrolling interest — 24,000 24,000 Balance, December 31, 2018 $ 283,292 $ 161,236 $ 444,528

Shareholders' Equity and Share-

Shareholders' Equity and Share-based Compensation	6 Months Ended
	Dec. 31, 2018
Share-based Compensation [Abstract]
Shareholders' Equity and Share-based Compensation	Shareholders' Equity and Share-based Compensation Share Repurchase In September 2017, the Board of Directors terminated the repurchase program that was previously approved in 2015 and approved a new repurchase program (the “Repurchase Program”), which allows the Company to repurchase its common shares from the open market pursuant to a pre-established Rule 10b5-1 trading plan or through privately negotiated transactions up to an aggregate of $30.0 million . The amount and timing of any repurchases under the Repurchase Program depend on a number of factors, including but not limited to, the trading price, volume, availability of the Company's common shares and the amount of available cash reserve. Shares repurchased under this program are accounted for as treasury shares and the total cost of shares repurchased is recorded as a reduction of shareholders' equity. During the six months ended December 31, 2018 , the Company repurchased an aggregate of 111,509 shares from the open market, for a total cost of $1.5 million , excluding fees and related expenses, at an average price of $13.43 per share. Since the inception of the prior repurchase program in 2010, the Company repurchased an aggregate of 6,784,648 shares from the open market including shares purchased in a dutch tender offer for a total cost of $67.3 million , at an average price of $9.92 per share, excluding fees and related expenses. No repurchased shares have been retired. Of the 6,784,648 repurchased shares, 133,728 shares with a weighted average repurchase price of $10.48 per share, were reissued at an average price of $5.77 per share pursuant to option exercises and vested restricted share units. As of December 31, 2018 , approximately $13.4 million remained available under the Repurchase Program. Time-based Restricted Stock Units ("TRSU") The following table summarizes the Company's TRSU activities for the six months ended December 31, 2018 : Number of Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Aggregate Intrinsic Value Nonvested at June 30, 2018 919,023 $ 15.14 1.62 $ 13,086,888 Granted 103,222 $ 11.96 Vested (68,182 ) $ 14.97 Forfeited (11,250 ) $ 13.63 Nonvested at December 31, 2018 942,813 $ 14.82 1.24 $ 9,607,264 TRSUs vested and expected to vest 874,061 1.18 $ 8,906,681 The Board approved the incentive bonus plan (the “Plan”) for the calendar year commencing January 1, 2018 pursuant to which each executive officer of the Company who continues in service through the end of the calendar year will be eligible to receive an incentive award, based on the level of attainment of certain specified Company performance goals. The Company recorded $1.0 million of such RSUs expenses during the three and six months ended December 31, 2018. The expenses are reported in the accrued liabilities line in the condensed consolidated balance sheet as the total amount of bonus is to be settled in variable number of shares. Such non-cash compensation expenses are recorded as part of stock-based compensation expense in the condensed consolidated statements of operations. Market-based Restricted Stock Units ("MSUs") During the quarter ended September 30, 2018, the Company granted 1.3 million market-based restricted stock units ("MSUs") to certain personnel. The number of shares to be earned at the end of performance period is determined based on the Company’s achievement of specified stock prices and revenue thresholds during the performance period from January 1, 2019 to December 31, 2021 as well as the recipients remaining in continuous service with the Company through such period. The MSUs vests in four equal annual installments after the end of each performance period. The Company estimated the grant date fair values of its MSUs with derived service periods of 4.5 to 7.5 years using a Monte-Carlo simulation model with the following assumptions: Risk-free interest rate of 2.7% , expected term of 3.5 years, expected volatility of 38.8% and dividend yield of 0% . The Company recorded approximately $0.2 million and $0.4 million of expenses for these MSUs during the three and six months ended December 31, 2018 . The following table summarizes the Company's MSUs activities for the six months ended December 31, 2018 : Number of Performance-based Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Nonvested at June 30, 2018 — $ — — Granted 1,310,000 $ 5.17 Vested — $ — Forfeited (20,000 ) $ 5.17 Nonvested at December 31, 2018 1,290,000 $ 5.17 5.46 MSUs vested and expected to vest 920,290 5.38 Performance-based Restricted Stock Units ("PRSUs") In March 2017 and 2018, the Company granted 170,000 and 298,000 performance-based RSUs (“PRSUs”) to certain personnel. The number shares to be earned under the PRSUs is determined based on the level of attainment of predetermined financial goals. The PRSUs vests in four equal annual installments from the first anniversary date after the grant date if certain predetermined financial goals were met. The Company recorded approximately $0.8 million and $1.4 million of expenses for these PRSUs during the three and six months ended December 31, 2018 , respectively, and approximately $0.5 million and $0.7 million during the three and six months ended December 31, 2017 , respectively. The following table summarizes the Company's PRSUs activities for the six months ended December 31, 2018 : Number of Performance-based Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Aggregate Intrinsic Value Nonvested at June 30, 2018 422,300 $ 16.63 2.06 $ 6,013,552 Granted — — Vested — — Forfeited (1,000 ) $ 16.22 Nonvested at December 31, 2018 421,300 $ 16.63 1.55 $ 4,293,047 PRSUs vested and expected to vest 383,347 1.48 $ 3,906,307 Stock Options The Company did not grant any stock options during the three and six months ended December 31, 2018 . The number of options expected to vest is the result of applying the pre-vesting forfeiture rate assumption to total outstanding options. The following table summarizes the Company's stock option activities for the six months ended December 31, 2018 : Weighted Weighted Average Average Remaining Number of Exercise Price Contractual Aggregate Shares Per Share Term (in years) Intrinsic Value Outstanding at June 30, 2018 886,978 $ 10.97 4.03 $ 3,557,248 Exercised (10,500 ) $ 10.50 $ 43,415 Outstanding at December 31, 2018 876,478 $ 10.98 3.56 $ 1,176,781 Options vested and expected to vest 876,478 $ 10.98 3.56 $ 1,176,781 Exercisable at December 31, 2018 876,478 $ 10.98 3.56 $ 1,176,781 Employee Share Purchase Plan ("ESPP") The assumptions used to estimate the fair values of common shares issued under the ESPP were as follows: Six Months Ended December 31, 2018 Volatility rate 40.1% Risk-free interest rate 2.5% - 2.9% Expected term 1.3 years Dividend yield 0% Share-based Compensation Expense T he total share-based compensation expense recognized in the condensed consolidated statements of operations for the periods presented was as follows: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Cost of goods sold $ 541 $ 415 $ 1,038 $ 731 Research and development 742 617 1,374 979 Selling, general and administrative 3,135 2,977 5,135 4,307 $ 4,418 $ 4,009 $ 7,547 $ 6,017 As of December 31, 2018 , total unrecognized compensation cost under the Company's equity plans was $15.8 million , which is expected to be recognized over a weighted-average period of 2.4 years.

Income Taxes

Income Taxes	6 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended December 31, 2018, the Company recognized income tax expense of approximately $0.7 million . For the three months ended December 31, 2017, the Company recognized income tax benefit of approximately $2.1 million , which included a discrete tax benefit of $2.7 million related to re-measuring the Company’s U.S. deferred tax assets and liabilities following enactment of the 2017 U.S. Tax Cut and Jobs Act in December 2017. Excluding the discrete income tax items, the estimated effective tax rate for the three months ended December 31, 2018 was (13.8)% compared to 31.4% for the three months ended December 31, 2017. The changes in the effective tax rate and tax expense between the periods resulted primarily from changes in the mix of earnings in various geographic jurisdictions between the current year and the same period of last year somewhat offset by the reduction in the U.S. corporate tax rate following the enactment of the 2017 U.S. Tax Cut and Jobs Act. For the six months ended December 31, 2018, the Company recognized income tax expense of approximately $1.3 million , which included a discrete tax expense of $0.03 million . For the six months ended December 31, 2017, the Company recognized an income tax benefit of approximately $0.8 million , which included a discrete tax benefit of $2.7 million related to remeasuring the Company’s U.S. deferred tax assets and liabilities following enactment of the 2017 U.S. Tax Cut and Jobs Act in December 2017. Excluding the discrete income tax items, the estimated effective tax rate for the six months ended December 31, 2018 was (23.7)% compared to 24.0% for the six months ended December 31, 2017. The changes in the effective tax rate and tax expense between the periods resulted primarily from the reduction in the U.S. corporate tax rate following the enactment of the 2017 U.S. Tax Cut and Jobs Act along with changes in the mix of earnings in various geographic jurisdictions between the current year and the same period of last year. The Company adopted ASC 606 using the modified retrospective method applied to those contracts which were not completed as of July 1, 2018. Results for reporting periods beginning after July 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under ASC 605. The adoption resulted in a derecognition of a deferred tax asset of $0.3 million related to previously unrecognized gross profit for U.S. GAAP purposes that was previously recognized for income tax purposes, with an offsetting reduction to retained earnings. The Company files its income tax returns in the United States and in various foreign jurisdictions. The tax years 2001 to 2018 remain open to examination by U.S. federal and state tax authorities. The tax years 2011 to 2018 remain open to examination by foreign tax authorities. The Company's income tax returns are subject to examinations by the Internal Revenue Service and other tax authorities in various jurisdictions. In accordance with the guidance on the accounting for uncertainty in income taxes, the Company regularly assesses the likelihood of adverse outcomes resulting from these examinations to determine the adequacy of its provision for income taxes. These assessments can require considerable estimates and judgments. As of December 31, 2018, the gross amount of unrecognized tax benefits was approximately $7.4 million , of which $4.5 million , if recognized, would reduce the effective income tax rate in future periods. If the Company's estimate of income tax liabilities proves to be less than the ultimate assessment, then a further charge to expense would be required. If events occur and the payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. The Company does not anticipate any material changes to its uncertain tax positions during the next twelve months. On July 27, 2015, in Altera Corp. v. Commissioner , the U.S. Tax Court issued an opinion related to the treatment of share-based compensation expense in an intercompany cost-sharing arrangement. A final decision has yet to be issued by the Tax Court due to other outstanding issues related to the case. At this time, the U.S. Department of the Treasury has not withdrawn the requirement to include share-based compensation from its regulations. Due to the uncertainty surrounding the status of the current regulations, questions related to the scope of potential benefits, and the risk of the Tax Court’s decision being overturned upon appeal, the Company has not recorded any benefit as of December 31, 2018. The Company will continue to monitor ongoing developments and potential impacts to its financial statements.

Segment and Geographic Informat

Segment and Geographic Information	6 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment and Geographic Information	Segment and Geographic Information The Company is organized as, and operates in, one operating segment: the design, development and supply of power semiconductor products for computing, consumer electronics, communication and industrial applications. The chief operating decision-maker is the Chief Executive Officer. The financial information presented to the Company's Chief Executive Officer is on a consolidated basis, accompanied by information about revenue by customer and geographic region, for purposes of evaluating financial performance and allocating resources. The Company has one business segment, and there are no segment managers who are held accountable for operations, operating results and plans for products or components below the consolidated unit level. Accordingly, the Company reports as a single operating segment. Long-lived assets, net consisting of property, plant and equipment and land use rights, by geographical area are as follows: December 31, June 30, (in thousands) China $ 294,437 $ 248,003 United States 85,678 83,040 Other Countries 668 613 $ 380,783 $ 331,656 For our revenues by geography, please refer to Note 2.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Purchase Commitments As of December 31, 2018 and June 30, 2018 , the Company had approximately $48.9 million and $38.0 million , respectively, of outstanding purchase commitments primarily for purchases of semiconductor raw materials, wafers, spare parts and packaging and testing services, and approximately $78.9 million and $58.3 million , respectively, of capital commitments for the purchase of property and equipment and EPC construction. Other Commitments See Note 6 and Note 7 of the Notes to the Condensed Consolidated Financial Statements contained in this Quarterly Report on Form 10-Q for descriptions of commitments including bank borrowings and Joint Venture . Contingencies and Indemnities The Company is currently not a party to any pending material legal proceedings. The Company has in the past, and may from time to time in the future, become involved in legal proceedings arising from the normal course of business activities. The semiconductor industry is characterized by frequent claims and litigation, including claims regarding patent and other intellectual property rights as well as improper hiring practices. Irrespective of the validity of such claims, the Company could incur significant costs in the defense of such claims and suffer adverse effects on its operations. The Company is a party to a variety of agreements that it has contracted with various third parties. Pursuant to these agreements, the Company may be obligated to indemnify another party to such an agreement with respect to certain matters. Typically, these obligations arise in the context of contracts entered into by the Company, under which the Company customarily agrees to hold the other party harmless against losses arising from a breach of representations and covenants related to such matters as title to assets sold, certain intellectual property rights, specified environmental matters and certain income taxes. In these circumstances, payment by the Company is customarily conditioned on the other party making a claim pursuant to the procedures specified in the particular contract, which procedures typically allow the Company to challenge the other party's claim. Further, the Company's obligations under these agreements may be limited in time and/or amount, and in some instances, the Company may have recourse against third parties for certain payments made by it under these agreements. The Company has not historically paid or recorded any material indemnifications, and no accrual has been made at December 31, 2018 and June 30, 2018 . The Company has agreed to indemnify its directors and certain employees as permitted by law and pursuant to its Bye-laws, and has entered into indemnification agreements with its directors and executive officers. The Company has not recorded a liability associated with these indemnification arrangements, as it historically has not incurred any material costs associated with such indemnification obligations. Costs associated with such indemnification obligations may be mitigated by insurance coverage that the Company maintains. However, such insurance may not cover any, or may cover only a portion of, the amounts the Company may be required to pay. In addition, the Company may not be able to maintain such insurance coverage in the future.

The Company and Significant A_2

The Company and Significant Accounting Policies (Policies)	6 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Preparation	Basis of Preparation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and with the instructions to Article 10 of Securities and Exchange Commission Regulation S-X, as amended. They do not include all information and footnotes necessary for a fair presentation of financial position, results of operations and cash flows in conformity with U.S. GAAP for complete financial statements. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018 . All significant intercompany balances and transactions have been eliminated in consolidation. In the opinion of management, all adjustments (consisting of normal recurring adjustments and accruals) considered necessary for a fair presentation of the results of operations for the periods presented have been included in the interim periods. Operating results for the six months ended December 31, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending June 30, 2019 . The condensed consolidated balance sheet at June 30, 2018 is derived from the audited financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018 .
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires the Company to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses. To the extent there are material differences between these estimates and actual results, the Company's condensed consolidated financial statements will be affected. On an ongoing basis, the Company evaluates the estimates, judgments and assumptions including those related to stock rotation returns, price adjustments, allowance for doubtful accounts, inventory reserves, warranty accrual, income taxes, share-based compensation, and useful lives for property, plant and equipment and intangible assets.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of cash equivalents is based on observable market prices and have been categorized in Level 1 in the fair value hierarchy. Cash equivalents consist primarily of short term bank deposits. The carrying values of financial instruments such as cash and cash equivalents, accounts receivable and accounts payable approximate their carrying values due to their short-term maturities. The carrying value of the company's debt is considered a reasonable estimate of fair value which is estimated by considering the current rates available to the Company for debt of the same remaining maturities, structure and terms of the debts.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. The Company's accumulated other comprehensive income (loss) consists of cumulative foreign currency translation adjustments. Total comprehensive income (loss) is presented in the condensed consolidated statements of comprehensive income (loss).
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Standards not yet adopted In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should be presented in the form of a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed with the SEC. The Company's first presentation of changes in stockholders' equity will be included in its Form 10-Q for the quarter ending March 31, 2019. In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-15 “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15”). These amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contact with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by these amendments. ASU 2018-15 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. The Company is currently assessing the impact that adoption of this guidance will have on its consolidated financial statements. In August 2018, the FASB issued Accounting Standard Updates ("ASU") ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement ("ASU 2018-13”). ASU 2018-13 amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. ASU No. 2018-13 is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2019. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial position, results of operations or cash flows. In June 2018, the FASB issued ASU 2018-07, "Compensation -Stock Compensation: Improvement to Nonemployees Share-Based Payment Accounting ("ASU 2018-07"), which expands the scope of Topic 718 to include all share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-07 specifies that Topic 718 applies to all share-based payment transactions in which the grantor acquires goods and services to be used or consumed in its own operations by issuing share-based payment awards. ASU 2018-07 also clarifies that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under ASC 606. ASU 2018-07 is effective fiscal years beginning after December 15, 2018, including interim periods within that fiscal year, with early adoption permitted, but no earlier than our adoption of ASC 606. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial position, results of operations or cash flows. In February 2016, the FASB issued ASU 2016-02, Leases. This guidance requires a dual approach for lessee accounting under which a lessee will account for leases as finance leases or operating leases. Both finance and operating leases will result in the lessee recognizing a right-of-use asset and a corresponding liability on its balance sheet, with differing methodology for income statement recognition. This guidance is effective for public business entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. A modified retrospective approach is required for all leases existing or entered into after the beginning of the earliest comparative period in the consolidated financial statements. In July 2018, the FASB issued ASU 2018-11, “Leases (Topic 842): Targeted Improvements.”, which permits an entity to elect an additional transition method to the existing modified retrospective transition requirements. Under the new transition method, an entity could adopt the provisions of ASU No. 2016-02 by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption without adjustment to the financial statements for periods prior to adoption. Consequently, an entity’s reporting for the comparative periods presented in the financial statements in which it adopts the new leases standard will continue to be in accordance with the previous lease guidance in ASC Topic 840. ASU 2018-11 also allows a practical expedient that permits lessors to not separate non-lease components from the associated lease component if certain conditions are present. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from previous Generally Accepted Accounting Principles. Although the Company is currently evaluating the impact the pronouncement will have on its consolidated financial statements and related disclosures, the Company expects that most of its operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon adoption. Recently Adopted Accounting Standards In May 2017, the FASB issued ASU 2017-09, "Compensation -Stock Compensation: Scope of Modification Accounting ("ASU 2017-09"). ASU 2017-09 is an update to the existing guidance to clarify when modification accounting would be applied for a change to the terms or conditions of a share-based award. Under this new guidance, modification accounting is required only if the fair value, a vesting condition, or the classification of the award changes as a result of the change in terms or conditions. This ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017 with early adoption permitted. The Company does not regularly modify the terms and conditions of its share-based awards and the adoption of this guidance has no impact on its financial statements. In November 2016, the FASB issued ASU 2016-18, "Statement of Cash Flows: Restricted Cash ("ASU 2016-18"). ASU 2016-18 requires amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the total beginning and ending amounts for the periods shown on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted and requires retrospective adoption. The Company adopted this standard effective July 1, 2018. The reclassified restricted cash balances from investing activities to changes in cash, cash equivalents and restricted cash on the condensed consolidated statements of cash flows were not material for all periods presented. In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"). ASU 2016-15 identifies how certain cash receipts and cash payments are presented and classified in the Statement of Cash Flows under Topic 230. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. Upon adoption, entities must apply the guidance retrospectively to all periods presented. There was no impact on the Company's consolidated financial statements upon the adoption of this standard. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606). The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The core principle of the model is to recognize revenue when control of the goods or services transfers to the customer, as opposed to recognizing revenue when the risks and rewards transfer to the customer under the existing revenue guidance. The change for the Company under ASC 606 relates to the timing of revenue recognition with two U.S.-based distributors. Sales to these distributors are governed under the terms of agreements providing extended price protection and other return rights, and were historically deferred under the previous accounting guidance until the related product was sold to the end customer. Under ASC 606, the transaction price takes into consideration the effect of variable consideration such as price adjustments and returns rights, which are estimated and recorded at the time the goods are delivered. Accordingly, the Company recognizes revenue under ASC 606 at the time of shipment or delivery to these two distributors, adjusted for estimates of the price adjustments and product returns based on historical data and other available information. Revenue from other non-U.S. distributors and direct customers, which consists of the majority of the Company's total revenue, is recognized at the time of shipment or delivery to the distributors and direct customers. Accordingly, revenue recognition with these distributors and direct customers remains unchanged upon adoption of ASC 606. See "Note 2 - Revenue" for additional information on the impact of the adoption of the new standard on the Company’s consolidated financial statements.
Concentration of Credit Risk	The Company manages its credit risk associated with exposure to distributors and direct customers on outstanding accounts receivable through the application and review of credit approvals, credit ratings and other monitoring procedures. In some instances, the Company also obtains letters of credit from certain customers. Credit sales, which are mainly on credit terms of 30 to 60 days , are only made to customers who meet the Company's credit requirements, while sales to new customers or customers with low credit ratings are usually made on an advance payment basis. The Company considers its trade accounts receivable to be of good credit quality because its key distributors and direct customers have long-standing business relationships with the Company and the Company has not experienced any significant write-offs of accounts receivable in the past. The Company closely monitors the aging of accounts receivable from its distributors and direct customers, and regularly reviews their financial positions, when available.

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following tables compare the amounts reported in the condensed consolidated statements of income and condensed consolidated balance sheet to the amounts had the previous revenue recognition guidance been in effect: As of December 31, 2018 As Reported Adjustment Balances Without Adoption (in thousands) Accounts receivable, net $ 33,858 $ 193 $ 34,051 Accrued liabilities $ 59,013 $ (84 ) $ 58,929 Deferred margin $ — $ 1,782 $ 1,782 Income taxes payable $ 1,769 $ (45 ) $ 1,724 Deferred income tax liabilities $ 1,134 $ (313 ) $ 821 Retained earnings $ 124,538 $ (1,183 ) $ 123,355 Three Months Ended December 31, 2018 Six Months Ended December 31, 2018 As Reported Adjustment Balances Without Adoption As Reported Adjustment Balances Without Adoption (in thousands) (in thousands) Revenue $ 114,925 $ (349 ) $ 114,576 $ 229,997 $ (308 ) $ 229,689 Cost of goods sold $ 85,423 $ (134 ) $ 85,289 $ 167,884 $ (114 ) $ 167,770 Gross profit $ 29,502 $ (215 ) $ 29,287 $ 62,113 $ (194 ) $ 61,919 Income tax expense (benefit) $ 701 $ (37 ) $ 664 $ 1,261 $ (45 ) $ 1,216 Net loss including noncontrolling interest $ (5,535 ) $ (178 ) $ (5,713 ) (6,448 ) $ (149 ) $ (6,597 )
Disaggregation of Revenue	The following table presents the Company's revenue information by geographical location based on the country or region to which the products were shipped. The Company sells its products primarily to distributors in the Asia Pacific region, who in turn sell these products to end customers. Because the Company's distributors sell their products to end customers which may have a global presence, revenue by geographical location is not necessarily representative of the geographical distribution of sales to end user markets. Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Hong Kong $ 87,180 $ 82,440 $ 178,771 $ 167,670 China 24,760 19,153 45,157 36,273 South Korea 139 301 308 588 United States 1,967 1,314 3,940 2,692 Other countries 879 688 1,821 1,531 $ 114,925 $ 103,896 $ 229,997 $ 208,754 The following is a summary of revenue by product type: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Power discrete $ 93,294 $ 85,094 $ 185,549 $ 168,772 Power IC 19,384 15,758 38,799 33,855 Packaging and testing services 2,247 3,044 5,649 6,127 $ 114,925 $ 103,896 $ 229,997 $ 208,754

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	6 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the calculation of basic and diluted net income (loss) per share attributable to common shareholders: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands, except per share data) Numerator: Net income (loss) attributable to Alpha and Omega Semiconductor Limited $ (1,545 ) $ 6,791 $ 871 $ 11,591 Denominator: Basic: Weighted average number of common shares used to compute basic net income (loss) per share 23,887 23,925 23,865 23,973 Diluted: Weighted average number of common shares used to compute basic net income per share 23,887 23,925 23,865 23,973 Effect of potentially dilutive securities: Stock options, RSUs and ESPP shares — 1,108 648 1,024 Weighted average number of common shares used to compute diluted net income per share 23,887 25,033 24,513 24,997 Net income (loss) per share attributable to Alpha and Omega Semiconductor Limited: Basic $ (0.06 ) $ 0.28 $ 0.04 $ 0.48 Diluted $ (0.06 ) $ 0.27 $ 0.04 $ 0.46
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potential dilutive securities were excluded from the computation of diluted net income per share as their effect would have been anti-dilutive: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Employee stock options and RSUs 2,225 165 646 169 ESPP 1,240 — 508 45 Total potential dilutive securities 3,465 165 1,154 214

Concentration of Credit Risk _2

Concentration of Credit Risk and Significant Customers (Tables)	6 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	Summarized below are individual customers whose revenue or accounts receivable balances were more than 10% of the respective total consolidated amounts: Three Months Ended December 31, Six Months Ended December 31, Percentage of revenue 2018 2017 2018 2017 Customer A 30.6 % 30.8 % 29.1 % 29.2 % Customer B 37.6 % 33.7 % 37.8 % 33.8 % December 31, June 30, Percentage of accounts receivable Customer A 25.0 % 17.1 % Customer B 35.1 % 35.5 % Customer C * 10.6 %

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	Accounts receivable, net: December 31, June 30, (in thousands) Accounts receivable $ 52,465 $ 52,687 Less: Allowance for price adjustments (18,577 ) (18,902 ) Less: Allowance for doubtful accounts (30 ) (30 ) Accounts receivable, net $ 33,858 $ 33,755
Schedule of Inventory, Current	Inventories: December 31, June 30, (in thousands) Raw materials $ 54,188 $ 47,097 Work in-process 39,307 35,243 Finished goods 9,467 7,842 $ 102,962 $ 90,182
Other Current Assets	Other current assets: December 31, June 30, (in thousands) VAT receivable $ 28,305 $ 17,601 Other prepaid expenses 2,603 2,121 Prepaid insurance 538 906 Prepaid maintenance 693 556 Prepayment to supplier 535 227 Prepaid income tax 747 761 Custom deposit 55 5,749 Lease financing cost 655 960 Other receivable 140 670 $ 34,271 $ 29,551
Property, Plant and Equipment	operty, plant and equipment, net: December 31, June 30, (in thousands) Land $ 4,877 $ 4,877 Building 33,884 4,325 Manufacturing machinery and equipment 285,078 265,192 Equipment and tooling 19,334 16,605 Computer equipment and software 28,062 25,686 Office furniture and equipment 2,794 2,314 Leasehold improvements 30,920 29,900 Land use rights 8,751 9,089 413,700 357,988 Less: accumulated depreciation (237,620 ) (225,184 ) 176,080 132,804 Equipment and construction in progress 204,703 198,852 Property, plant and equipment, net $ 380,783 $ 331,656
Intangible Assets Disclosure	Intangible assets, net: December 31, June 30, (in thousands) Patents and technology rights $ 18,037 $ 17,633 Trade name 268 268 Customer relationships 1,150 1,150 19,455 19,051 Less: accumulated amortization (2,785 ) (2,729 ) 16,670 16,322 Goodwill 269 269 Intangible assets, net $ 16,939 $ 16,591
Schedule of Other Assets, Noncurrent	Other long-term assets: December 31, June 30, (in thousands) Prepayments for property and equipment $ 6,222 $ 17,599 Investment in a privately held company 700 700 Lease financing costs 1,650 1,922 VAT long-term receivable 4 3,396 Custom deposit 1,701 1,589 Other long-term deposits 1,812 2,252 Office leases deposits 989 853 Other 466 387 $ 13,544 $ 28,698
Schedule of Accrued Liabilities	Accrued liabilities: December 31, June 30, (in thousands) Accrued compensation and benefits $ 29,694 $ 18,484 Warranty accrual 655 535 Stock rotation accrual 1,847 1,750 Accrued professional fees 1,738 1,922 Accrued inventory 1,340 667 Accrued facilities related expenses 1,879 2,163 Accrued financing lease costs 727 1,510 Accrued property, plant and equipment 13,090 18,145 Other accrued expenses 8,043 4,665 $ 59,013 $ 49,841
Schedule of Product Warranty Liability	The activities in the warranty accrual, included in accrued liabilities, are as follows: Six Months Ended December 31, 2018 2017 (in thousands) Beginning balance $ 535 $ 1,866 Additions (reductions) 189 (1,063 ) * Utilization (69 ) (36 ) Ending balance $ 655 $ 767 * Released a specific warranty reserve of approximately $1.0 million due to expired warranty period.
Stock Rotation Accrual	The activities in the stock rotation accrual, included in accrued liabilities, are as follows: Six Months Ended December 31, 2018 2017 (in thousands) Beginning balance $ 1,750 $ 1,871 Additions 2,229 992 Utilization (2,132 ) (1,252 ) Ending balance $ 1,847 $ 1,611

Bank Borrowing (Tables)

Bank Borrowing (Tables)	6 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Capital Lease Liabilities	Capital lease liabilities include financing leases, computer software and exclusive technology rights. Future minimum lease payments are as follows (in thousands): Year ending June 30, 2019 (Remaining) $ 5,530 2020 14,203 2021 17,778 2022 16,909 2023 12,255 Total minimum lease payments 66,675 Less amount representing interest (8,061 ) Total capital lease liabilities $ 58,614
Schedule of Maturities	Maturities of Jireh debt were as follows (in thousands): Year ending June 30, 2019 (Remaining) $ 4,170 2020 8,340 2021 8,340 2022 8,340 2023 16,028 Total principal of debt 45,218 Less: debt issuance costs (233 ) Total principal of debt, less debt issuance costs $ 44,985

Joint Venture (Tables)

Joint Venture (Tables)	6 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Stockholders Equity	The changes in total AOS shareholders' equity, noncontrolling interest and total equity were as follows (in thousands): Total AOS Shareholders' Equity Noncontrolling Interest Total Equity Balance, June 30, 2018 $ 278,594 $ 147,568 $ 426,162 Exercise of common stock options and release of RSUs 110 — 110 Withholding tax on restricted stock units (203 ) — (203 ) Issuance of shares under ESPP 1,168 — 1,168 Repurchase of common shares under shares repurchase program (1,501 ) — (1,501 ) Share-based compensation expense 6,499 — 6,499 Net income (loss) 871 (7,319 ) (6,448 ) Impact on retained earnings related to ASC 606 adoption 1,036 — 1,036 Cumulative translation adjustment (3,282 ) (3,013 ) (6,295 ) Contributions from noncontrolling interest — 24,000 24,000 Balance, December 31, 2018 $ 283,292 $ 161,236 $ 444,528

Shareholders' Equity and Shar_2

Shareholders' Equity and Share-based Compensation (Tables)	6 Months Ended
	Dec. 31, 2018
Share-based Compensation [Abstract]
Restricted Stock Units Activity	Time-based Restricted Stock Units ("TRSU") The following table summarizes the Company's TRSU activities for the six months ended December 31, 2018 : Number of Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Aggregate Intrinsic Value Nonvested at June 30, 2018 919,023 $ 15.14 1.62 $ 13,086,888 Granted 103,222 $ 11.96 Vested (68,182 ) $ 14.97 Forfeited (11,250 ) $ 13.63 Nonvested at December 31, 2018 942,813 $ 14.82 1.24 $ 9,607,264 TRSUs vested and expected to vest 874,061 1.18 $ 8,906,681 The following table summarizes the Company's MSUs activities for the six months ended December 31, 2018 : Number of Performance-based Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Nonvested at June 30, 2018 — $ — — Granted 1,310,000 $ 5.17 Vested — $ — Forfeited (20,000 ) $ 5.17 Nonvested at December 31, 2018 1,290,000 $ 5.17 5.46 MSUs vested and expected to vest 920,290 5.38 The following table summarizes the Company's PRSUs activities for the six months ended December 31, 2018 : Number of Performance-based Restricted Stock Units Weighted Average Grant Date Fair Value Per Share Weighted Average Remaining Recognition Period (Years) Aggregate Intrinsic Value Nonvested at June 30, 2018 422,300 $ 16.63 2.06 $ 6,013,552 Granted — — Vested — — Forfeited (1,000 ) $ 16.22 Nonvested at December 31, 2018 421,300 $ 16.63 1.55 $ 4,293,047 PRSUs vested and expected to vest 383,347 1.48 $ 3,906,307
Summary of Stock Option Activities	The following table summarizes the Company's stock option activities for the six months ended December 31, 2018 : Weighted Weighted Average Average Remaining Number of Exercise Price Contractual Aggregate Shares Per Share Term (in years) Intrinsic Value Outstanding at June 30, 2018 886,978 $ 10.97 4.03 $ 3,557,248 Exercised (10,500 ) $ 10.50 $ 43,415 Outstanding at December 31, 2018 876,478 $ 10.98 3.56 $ 1,176,781 Options vested and expected to vest 876,478 $ 10.98 3.56 $ 1,176,781 Exercisable at December 31, 2018 876,478 $ 10.98 3.56 $ 1,176,781
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]	The assumptions used to estimate the fair values of common shares issued under the ESPP were as follows: Six Months Ended December 31, 2018 Volatility rate 40.1% Risk-free interest rate 2.5% - 2.9% Expected term 1.3 years Dividend yield 0%
Share-based Compensation, Allocation of Recognized Period Costs	Share-based Compensation Expense T he total share-based compensation expense recognized in the condensed consolidated statements of operations for the periods presented was as follows: Three Months Ended December 31, Six Months Ended December 31, 2018 2017 2018 2017 (in thousands) (in thousands) Cost of goods sold $ 541 $ 415 $ 1,038 $ 731 Research and development 742 617 1,374 979 Selling, general and administrative 3,135 2,977 5,135 4,307 $ 4,418 $ 4,009 $ 7,547 $ 6,017

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	6 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	Long-lived assets, net consisting of property, plant and equipment and land use rights, by geographical area are as follows: December 31, June 30, (in thousands) China $ 294,437 $ 248,003 United States 85,678 83,040 Other Countries 668 613 $ 380,783 $ 331,656

The Company and Significant A_3

The Company and Significant Accounting Policies - Joint Venture (Details) - Facility in Liangjiang New Area of Chongqing (the 'Joint Venture') - USD ($) $ in Millions	Dec. 28, 2018	Sep. 30, 2018	Aug. 31, 2018	Mar. 29, 2016
Consideration transferred to acquire interest in joint venture			$ 25
Parent Company
Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions	50.90%	54.40%	54.40%
Chongqing Funds
Consideration transferred to acquire interest in joint venture	$ 24
Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions	49.10%	45.60%	45.60%
Corporate Joint Venture
Initial capitalization of joint venture				$ 330

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 01, 2018	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Change in deferred margin	$ 0		$ (1,665)
Change in accounts receivable	(33,858)		(33,755)
Change in current accrued liabilities	59,013		$ 49,841
Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Net increase to opening retained earnings		$ 1,000
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Change in deferred margin	1,782	1,600
Change in accounts receivable	193	200
Change in current accrued liabilities	$ 84	100
Change in deferred tax assets		$ 300

Revenue - Effect on Balance She

Revenue - Effect on Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 01, 2018	Jun. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 33,858		$ 33,755
Accrued liabilities	59,013		49,841
Deferred margin	0		1,665
Income taxes payable	1,769		2,211
Deferred income tax liabilities	1,134		713
Retained earnings	124,538		$ 122,639
Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	(193)	$ (200)
Accrued liabilities	84	100
Deferred margin	(1,782)	$ (1,600)
Income taxes payable	45
Deferred income tax liabilities	313
Retained earnings	1,183
Balances Without Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	34,051
Accrued liabilities	58,929
Deferred margin	1,782
Income taxes payable	1,724
Deferred income tax liabilities	821
Retained earnings	$ 123,355

Revenue - Effect on Income Stat

Revenue - Effect on Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 114,925	$ 103,896	$ 229,997	$ 208,754
Cost of goods sold	85,423	75,814	167,884	153,142
Gross profit	29,502	28,082	62,113	55,612
Income tax expense (benefit)	701	(2,072)	1,261	(798)
Net loss including noncontrolling interest	(5,535)	$ 5,122	(6,448)	$ 8,461
Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	(349)		(308)
Cost of goods sold	(134)		(114)
Gross profit	(215)		(194)
Income tax expense (benefit)	(37)		(45)
Net loss including noncontrolling interest	(178)		(149)
Balances Without Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	114,576		229,689
Cost of goods sold	85,289		167,770
Gross profit	29,287		61,919
Income tax expense (benefit)	664		1,216
Net loss including noncontrolling interest	$ (5,713)		$ (6,597)

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 114,925	$ 103,896	$ 229,997	$ 208,754
Power discrete
Disaggregation of Revenue [Line Items]
Revenue	93,294	85,094	185,549	168,772
Power IC
Disaggregation of Revenue [Line Items]
Revenue	19,384	15,758	38,799	33,855
Packaging and testing services
Disaggregation of Revenue [Line Items]
Revenue	2,247	3,044	5,649	6,127
Hong Kong
Disaggregation of Revenue [Line Items]
Revenue	87,180	82,440	178,771	167,670
China
Disaggregation of Revenue [Line Items]
Revenue	24,760	19,153	45,157	36,273
South Korea
Disaggregation of Revenue [Line Items]
Revenue	139	301	308	588
United States
Disaggregation of Revenue [Line Items]
Revenue	1,967	1,314	3,940	2,692
Other Countries
Disaggregation of Revenue [Line Items]
Revenue	$ 879	$ 688	$ 1,821	$ 1,531

Net Income (Loss) Per Share - B

Net Income (Loss) Per Share - Basic and Diluted Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income (loss) attributable to Alpha and Omega Semiconductor Limited	$ (1,545)	$ 6,791	$ 871	$ 11,591
Basic:
Weighted average number of common shares used to compute basic net income (loss) per share	23,887	23,925	23,865	23,973
Effect of potentially dilutive securities:
Stock options, RSUs and ESPP shares	0	1,108	648	1,024
Weighted average number of common shares used to compute diluted net income per share	23,887	25,033	24,513	24,997
Net income (loss) per share attributable to Alpha and Omega Semiconductor Limited:
Basic (in dollars per share)	$ (0.06)	$ 0.28	$ 0.04	$ 0.48
Diluted (in dollars per share)	$ (0.06)	$ 0.27	$ 0.04	$ 0.46

Net Income (Loss) Per Share - P

Net Income (Loss) Per Share - Potential Dilutive Shares (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities (in shares)	3,465	165	1,154	214
Employee stock options and RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities (in shares)	2,225	165	646	169
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities (in shares)	1,240	0	508	45

Concentration of Credit Risk _3

Concentration of Credit Risk and Significant Customers - (Details)	3 Months Ended			6 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Minimum
Concentration Risk
Terms of credit sales, (in days)				30 days
Maximum
Concentration Risk
Terms of credit sales, (in days)				60 days
Customer A | Sales Revenue, Goods, Net | Customer Concentration Risk
Concentration Risk
Customers greater than 10% of total	30.60%		30.80%	29.10%	29.20%
Customer A | Accounts Receivable | Customer Concentration Risk
Concentration Risk
Customers greater than 10% of total	25.00%	17.10%
Customer B | Sales Revenue, Goods, Net | Customer Concentration Risk
Concentration Risk
Customers greater than 10% of total	37.60%		33.70%	37.80%	33.80%
Customer B | Accounts Receivable | Customer Concentration Risk
Concentration Risk
Customers greater than 10% of total	35.10%	35.50%
Customer C | Accounts Receivable | Customer Concentration Risk
Concentration Risk
Customers greater than 10% of total		10.60%

Balance Sheet Components - Acco

Balance Sheet Components - Accounts receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Accounts receivable	$ 52,465	$ 52,687
Less: Allowance for price adjustments	(18,577)	(18,902)
Less: Allowance for doubtful accounts	(30)	(30)
Accounts receivable, net	$ 33,858	$ 33,755

Balance Sheet Components - Inve

Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 54,188	$ 47,097
Work in-process	39,307	35,243
Finished goods	9,467	7,842
Inventory, net	$ 102,962	$ 90,182

Balance Sheet Components - Othe

Balance Sheet Components - Other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Balance Sheet Related Disclosures [Abstract]
VAT receivable	$ 28,305	$ 17,601
Other prepaid expenses	2,603	2,121
Prepaid Insurance	538	906
Prepaid Maintenance, Current	693	556
Prepayment to supplier	535	227
Prepaid income tax	747	761
Customs deposit	55	5,749
Lease Financing Costs, Current	655	960
Other receivable	140	670
Other Assets, Current	$ 34,271	$ 29,551

Balance Sheet Components - Prop

Balance Sheet Components - Property, plant, and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	$ 413,700	$ 357,988
Land use rights	8,751	9,089
Less: accumulated depreciation	(237,620)	(225,184)
Property, plant and equipment excluding equipment and construction in progress, net	176,080	132,804
Equipment and construction in progress	204,703	198,852
Property, plant and equipment, net	380,783	331,656
Land
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	4,877	4,877
Building
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	33,884	4,325
Manufacturing machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	285,078	265,192
Equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	19,334	16,605
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	28,062	25,686
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	2,794	2,314
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment excluding equipment and construction In progress, gross	$ 30,920	$ 29,900

Balance Sheet Components - Inta

Balance Sheet Components - Intangible assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Schedule of Finite-lived Intangible Assets and Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	$ 19,455	$ 19,051
Less: accumulated amortization	(2,785)	(2,729)
Intangible Assets, Net (Excluding Goodwill)	16,670	16,322
Goodwill	269	269
Intangible assets, net	16,939	16,591
Patents and technology rights
Schedule of Finite-lived Intangible Assets and Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	18,037	17,633
Trade name
Schedule of Finite-lived Intangible Assets and Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	268	268
Customer relationships
Schedule of Finite-lived Intangible Assets and Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	$ 1,150	$ 1,150

Balance Sheet Components - In_2

Balance Sheet Components - Intangible Assets, Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Payments to Acquire Intangible Assets	$ 405	$ 10,384
STMicro | License fees
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 16,200

Balance Sheet Components - Ot_2

Balance Sheet Components - Other long term assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Prepayments for property and equipment	$ 6,222	$ 17,599
Investment in a privately held company	700	700
Lease financing costs, noncurrent	1,650	1,922
VAT long-term receivable	4	3,396
Custom deposit, noncurrent	1,701	1,589
Other long-term deposits	1,812	2,252
Office lease deposit, noncurrent	989	853
Other	466	387
Other long-term assets	$ 13,544	$ 28,698

Balance Sheet Components - Accr

Balance Sheet Components - Accrued liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and benefits	$ 29,694	$ 18,484
Warranty accrual	655	535	$ 767	$ 1,866
Stock rotation accrual	1,847	1,750	$ 1,611	$ 1,871
Accrued professional fees	1,738	1,922
Accrued inventory	1,340	667
Accrued facilities related expenses	1,879	2,163
Accrued financing lease costs	727	1,510
Accrued property, plant and equipment	13,090	18,145
Other accrued expenses	8,043	4,665
Accrued liabilities	$ 59,013	$ 49,841

Balance Sheet Components - Prod

Balance Sheet Components - Product Warranty Accrual (Details) - USD ($) $ in Thousands	6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Beginning balance	$ 535	$ 1,866
Additions (reductions)	189	(1,063)
Utilization	(69)	(36)
Ending balance	$ 655	767
Standard Product Warranty Accrual, Increase (Decrease) for Specific Warranty Reserve		$ (1,000)

Balance Sheet Components - Stoc

Balance Sheet Components - Stock Rotation Accrual (Details) - USD ($) $ in Thousands	6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock Rotation Accrual Increae (Decrease) [Roll Forward]
Beginning balance	$ 1,750	$ 1,871
Additions	2,229	992
Utilization	(2,132)	(1,252)
Ending balance	$ 1,847	$ 1,611

Bank Borrowing (Details)

Bank Borrowing (Details) $ in Thousands	May 09, 2018USD ($)	Aug. 15, 2017USD ($)	Dec. 31, 2018USD ($)	Nov. 30, 2018USD ($)	Jul. 31, 2018USD ($)	Jan. 31, 2018USD ($)	Dec. 31, 2018CNY (¥)	Dec. 04, 2018CNY (¥)	Nov. 29, 2018CNY (¥)	Nov. 16, 2018USD ($)	Nov. 16, 2018CNY (¥)	May 09, 2018CNY (¥)	May 01, 2018USD ($)
Capital lease liability
2019 (Remaining)			$ 5,530
2,020			14,203
2,021			17,778
2,022			16,909
2,023			12,255
Total minimum lease payments			66,675
Less amount representing interest			(8,061)
Total capital lease liabilities			58,614
Maturities of debt
2019 (Remaining)			4,170
2,020			8,340
2,021			8,340
2,022			8,340
2,023			16,028
Total principal of debt			45,218
Less: debt issuance costs			(233)
Total principal of debt, less debt issuance costs			44,985
Loan Agreement November 29 2018
Debt Instrument [Line Items]
Debt instrument, face amount | ¥									¥ 80,000,000
Loan agreements, short-term debt | ¥							¥ 80,000,000
Loan Agreement December 4 2018
Debt Instrument [Line Items]
Debt instrument, face amount | ¥								¥ 20,000,000
Loan agreements, short-term debt | ¥							20,000,000
Loan Agreements November 29 And December 4 2018
Debt Instrument [Line Items]
Debt instrument, face amount			14,500
Loan agreements, short-term debt			14,500
Secured Debt
Debt Instrument [Line Items]
Stated percentage													5.04%
Line of credit facility, maximum borrowing capacity													$ 17,800
Amount outstanding			17,300
Term Loan | Secured Debt | Variable Interest Rate Term Loan Maturing August 2022
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 30,000
Debt instrument, term		5 years
Amount outstanding			27,900
Proceeds from lines of credit					$ 16,700	$ 13,200
Minimum | London Interbank Offered Rate (LIBOR) | Term Loan | Secured Debt | Variable Interest Rate Term Loan Maturing August 2022
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Maximum | London Interbank Offered Rate (LIBOR) | Term Loan | Secured Debt | Variable Interest Rate Term Loan Maturing August 2022
Debt Instrument [Line Items]
Basis spread on variable rate		2.25%
YinHai Leasing Company and China Import/Export Bank | Lease Financing
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 62,800											¥ 400,000,000
Nominal sale amount at end of lease term | ¥												¥ 1
Amount outstanding			58,200				¥ 400,000,000
China | YinHai Leasing Company and China Import/Export Bank | Base Rate | Lease Financing
Debt Instrument [Line Items]
Basis spread on variable rate, multiple	1.15											1.15
Basis spread on variable rate	5.4625%
Foreign Line of Credit | Industrial And Commercial Bank of China
Debt Instrument [Line Items]
Loan agreements, short-term debt										$ 10,300	¥ 72,000,000
Proceeds from short-term debt				$ 5,000
Stated percentage				3.64%
Repayments of short-term debt			$ 5,000

Joint Venture - Narrative (Deta

Joint Venture - Narrative (Details) $ in Millions	Dec. 28, 2018USD ($)	Sep. 30, 2018	Aug. 31, 2018	Dec. 31, 2018USD ($)	Dec. 31, 2018CNY (¥)	Dec. 31, 2018CNY (¥)	Jan. 10, 2017USD ($)	Jan. 10, 2017CNY (¥)
Parent Company | Facility in Liangjiang New Area of Chongqing (the 'Joint Venture')
Schedule of Equity Method Investments [Line Items]
Percent ownership in joint venture	50.90%	54.40%	54.40%
Chongqing Funds | Facility in Liangjiang New Area of Chongqing (the 'Joint Venture')
Schedule of Equity Method Investments [Line Items]
Percent ownership in joint venture	49.10%	45.60%	45.60%
Contributions from noncontrolling interest	$ 24
Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Total price payable under EPC Contract							$ 78	¥ 540,000,000
Contractual obligation, payment				$ 68.3	¥ 470,000,000
Contract amount payable in fiscal year 2019				$ 10.2		¥ 70,000,000
Corporate Joint Venture | Design Fees
Schedule of Equity Method Investments [Line Items]
Total price payable under EPC Contract							2.8	19,500,000
Corporate Joint Venture | Construction and Procurement Fees
Schedule of Equity Method Investments [Line Items]
Total price payable under EPC Contract							$ 75.2	¥ 520,500,000

Joint Venture - Changes in Tota

Joint Venture - Changes in Total Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		98 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Balance, June 30, 2018			$ 426,162
Exercise of common stock options and release of RSUs			110
Withholding tax on restricted stock units			(203)
Issuance of shares under ESPP			1,168
Repurchase of common shares under shares repurchase program			(1,501)		$ (67,300)
Share-based compensation expense			6,499
Net income (loss)	$ (5,535)	$ 5,122	(6,448)	$ 8,461
Net loss attributable to noncontrolling interest	(3,990)	$ (1,669)	(7,319)	(3,130)
Cumulative translation adjustment			(6,295)
Contributions from noncontrolling interest			24,000	$ 86,994
Balance, December 31, 2018	444,528		444,528		444,528
Accounting Standards Update 2016-16
Schedule of Equity Method Investments [Line Items]
Impact on retained earnings related to ASC 606 adoption			1,036
Parent
Schedule of Equity Method Investments [Line Items]
Balance, June 30, 2018			278,594
Exercise of common stock options and release of RSUs			110
Withholding tax on restricted stock units			(203)
Issuance of shares under ESPP			1,168
Repurchase of common shares under shares repurchase program			(1,501)
Share-based compensation expense			6,499
Net income (loss)			871
Cumulative translation adjustment			(3,282)
Contributions from noncontrolling interest			0
Balance, December 31, 2018	283,292		283,292		283,292
Parent | Accounting Standards Update 2016-16
Schedule of Equity Method Investments [Line Items]
Impact on retained earnings related to ASC 606 adoption			1,036
Noncontrolling Interest
Schedule of Equity Method Investments [Line Items]
Balance, June 30, 2018			147,568
Exercise of common stock options and release of RSUs			0
Withholding tax on restricted stock units			0
Issuance of shares under ESPP			0
Repurchase of common shares under shares repurchase program			0
Share-based compensation expense			0
Net loss attributable to noncontrolling interest			(7,319)
Cumulative translation adjustment			(3,013)
Contributions from noncontrolling interest			24,000
Balance, December 31, 2018	$ 161,236		161,236		$ 161,236
Noncontrolling Interest | Accounting Standards Update 2016-16
Schedule of Equity Method Investments [Line Items]
Impact on retained earnings related to ASC 606 adoption			$ 0

Shareholders' Equity and Shar_3

Shareholders' Equity and Share-based Compensation - Shares Repurchase (Details) $ / shares in Units, $ in Thousands	6 Months Ended	98 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Class of Stock [Line Items]
Treasury Stock, Shares, Retired | shares	0
Share repurchase program, authorized amount (USD in Millions)	$ 30,000	$ 30,000
Repurchase of common shares under shares repurchase program | shares	111,509	6,784,648
Treasury stock repurchased	$ 1,500
Treasury stock acquired, average price per share (in dollars per share) | $ / shares	$ 13.43	$ 9.92
Repurchase of common shares under shares repurchase program	$ (1,501)	$ (67,300)
Shares repurchase program, remaining balance	$ 13,400	$ 13,400
Treasury Stock Reissued
Class of Stock [Line Items]
Treasury stock acquired, average price per share (in dollars per share) | $ / shares		$ 10.48
Shares reissued (in shares) | shares		133,728
Shares reissued, average price (in dollars per share) | $ / shares		$ 5.77

Shareholders' Equity and Shar_4

Shareholders' Equity and Share-based Compensation - Time-based Restricted Stock Activity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average remaining recognition period (in years)	2 years 4 months 24 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at June 30, 2018 (in shares)			919,023
Granted (in shares)			103,222
Vested (in shares)			(68,182)
Forfeited (in shares)			(11,250)
Nonvested at December 31, 2018 (in shares)	942,813	919,023	942,813
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested at June 30, 2018 (in dollars per share)			$ 15.14
Granted (in dollars per share)			11.96
Vested (in dollars per share)			14.97
Forfeited (in dollars per share)			13.63
Nonvested at December 31, 2018 (in dollars per share	$ 14.82	$ 15.14	$ 14.82
Weighted average remaining recognition period (in years)	1 year 2 months 27 days	1 year 7 months 13 days
Aggregate Intrinsic Value	$ 9,607,264	$ 13,086,888	$ 9,607,264
Vested and expected to vest (in shares)	874,061		874,061
Vested and expected to vest (in years)	1 year 2 months 5 days
Vested and expected to vest	$ 8,906,681		$ 8,906,681
Incentive Bonus Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Restricted stock unit expense	$ 1,000,000

Shareholders' Equity and Shar_5

Shareholders' Equity and Share-based Compensation - Market-based Restricted Stock Units Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 4,418		$ 4,009	$ 7,547	$ 6,017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average remaining recognition period (in years)	2 years 4 months 24 days
Market-based Restricted Stock Units (MSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate				2.70%
Expected term				3 years 6 months
Expected volatility				38.80%
Dividend yield				0.00%
Allocated share-based compensation expense	$ 200			$ 400
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at June 30, 2018 (in shares)				0
Granted (in shares)				1,310,000
Vested (in shares)				0
Forfeited (in shares)				(20,000)
Nonvested at December 31, 2018 (in shares)	1,290,000	0		1,290,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested at June 30, 2018 (in dollars per share)				$ 0
Granted (in dollars per share)				5.17
Vested (in dollars per share)				0
Forfeited (in dollars per share)				5.17
Nonvested at December 31, 2018 (in dollars per share	$ 5.17	$ 0		$ 5.17
Weighted average remaining recognition period (in years)	5 years 5 months 16 days	0 years
Vested and expected to vest (in shares)	920,290			920,290
Vested and expected to vest (in years)	5 years 4 months 17 days
Market-based Restricted Stock Units (MSU) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period				4 years 6 months
Market-based Restricted Stock Units (MSU) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period				7 years 6 months

Shareholders' Equity and Shar_6

Shareholders' Equity and Share-based Compensation - Performance-based Restricted Stock Units (Details) - USD ($)	1 Months Ended		3 Months Ended			6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			$ 4,418,000		$ 4,009,000	$ 7,547,000	$ 6,017,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average remaining recognition period (in years)			2 years 4 months 24 days
Performance Based Restricted Stock Units (PRSUs) Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			$ 800,000		$ 500,000	$ 1,400,000	$ 700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at June 30, 2018 (in shares)						422,300
Granted (in shares)	298,000	170,000				0
Vested (in shares)						0
Forfeited (in shares)						(1,000)
Nonvested at December 31, 2018 (in shares)			421,300	422,300		421,300
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested at June 30, 2018 (in dollars per share)						$ 16.63
Granted (in dollars per share)						0
Vested (in dollars per share)						0
Forfeited (in dollars per share)						16.22
Nonvested at December 31, 2018 (in dollars per share			$ 16.63	$ 16.63		$ 16.63
Weighted average remaining recognition period (in years)			1 year 6 months 18 days	2 years 22 days
Aggregate Intrinsic Value			$ 4,293,047	$ 6,013,552		$ 4,293,047
Vested and expected to vest (in shares)			383,347			383,347
Vested and expected to vest (in years)			1 year 5 months 23 days
Vested and expected to vest			$ 3,906,307			$ 3,906,307

Shareholders' Equity and Shar_7

Shareholders' Equity and Share-based Compensation - Stock Options Outstanding and Exercisable (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2018
Share-based Compensation [Abstract]
Options, Number Outstanding (in shares)	876,478	886,978	876,478
Options, Weighted-Average Remaining Contractual Life (in years)		4 years 11 days	3 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 1,176,781	$ 3,557,248	$ 1,176,781
Options, Weighted-Average Exercise Price (in dollars per share)	$ 10.98	$ 10.97	$ 10.98
Options, Number Exercisable (in shares)	876,478		876,478
Options, Weighted-Average Exercise Price (in dollars per share)	$ 10.98		$ 10.98
Options vested and expected to vest, Number Outstanding (in shares)	876,478		876,478
Options vested and expected to vest, Weighted Average Remaining Contractual Life (in years)			3 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 1,176,781		$ 1,176,781
Options vested and expected to vest, Weighted Average Exercise Price (in dollars per share)	$ 10.98		$ 10.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			10,500
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price			$ 10.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value			$ 43,415
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	3 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 1,176,781		$ 1,176,781

Shareholders' Equity and Shar_8

Shareholders' Equity and Share-based Compensation - Employee Share Purchase Plan (Details) - Employee Stock [Member]	6 Months Ended
	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility rate	40.10%
Expected term	1 year 3 months 18 days
Dividend yield	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.50%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.90%

Shareholders' Equity and Shar_9

Shareholders' Equity and Share-based Compensation - Share-based Compensation (Details) - USD ($)	1 Months Ended		3 Months Ended			6 Months Ended		98 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			$ 4,418,000		$ 4,009,000	$ 7,547,000	$ 6,017,000
Repurchase of common shares under shares repurchase program						111,509		6,784,648
Options, Weighted-Average Remaining Contractual Life (in years)				4 years 11 days		3 years 6 months 22 days
Options vested and expected to vest, Number Outstanding (in shares)			876,478			876,478		876,478
Options vested and expected to vest, Weighted Average Exercise Price (in dollars per share)			$ 10.98			$ 10.98		$ 10.98
Options vested and expected to vest, Weighted Average Remaining Contractual Life (in years)						3 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value			$ 1,176,781			$ 1,176,781		$ 1,176,781
Options, Number Exercisable (in shares)			876,478			876,478		876,478
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price			$ 10.98			$ 10.98		$ 10.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term			3 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value			$ 1,176,781			$ 1,176,781		$ 1,176,781
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at June 30, 2018						886,978
Exercised (in shares)						(10,500)
Outstanding at September 30, 2018			876,478	886,978		876,478		876,478
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding at June 30, 2018 (in dollars per share)						$ 10.97
Exercised (in dollars per share)						10.50
Outstanding at September 30, 2018 (in dollars per share)			$ 10.98	$ 10.97		$ 10.98		$ 10.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value			$ 1,176,781	$ 3,557,248		$ 1,176,781		$ 1,176,781
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value						43,415
Market-based Restricted Stock Units (MSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			200,000			$ 400,000
Granted (in shares)						1,310,000
Performance Based Restricted Stock Units (PRSUs) Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense			$ 800,000		$ 500,000	$ 1,400,000	$ 700,000
Granted (in shares)	298,000	170,000				0

Shareholders' Equity and Sha_10

Shareholders' Equity and Share-based Compensation - Share-based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 4,418	$ 4,009	$ 7,547	$ 6,017
Unrecognized compensation expense	$ 15,800		15,800
Recognition period of share-based compensation expense (in years)	2 years 4 months 24 days
Cost of goods sold
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 541	415	1,038	731
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	742	617	1,374	979
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 3,135	$ 2,977	$ 5,135	$ 4,307

Income Taxes - Narrative (Deta

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)		$ 701	$ (2,072)	$ 1,261	$ (798)
Discrete income tax expense (benefit)			$ 2,700	$ 0	$ 2,700
Estimated effective income tax rate excluding discrete income tax expense		(13.80%)	31.40%	(23.70%)	24.00%
Unrecognized tax benefits		$ 7,400		$ 7,400
Unrecognized tax benefit that would impact effective tax rate		4,500		4,500
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)		$ (37)		$ (45)
Derecognition of deferred tax asset	$ 300

Segment and Geographic Inform_3

Segment and Geographic Information - Revenue by Location and Product Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 114,925	$ 103,896	$ 229,997	$ 208,754
Power discrete
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	93,294	85,094	185,549	168,772
Power IC
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	19,384	15,758	38,799	33,855
Packaging and testing services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,247	3,044	5,649	6,127
Hong Kong
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	87,180	82,440	178,771	167,670
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	24,760	19,153	45,157	36,273
South Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	139	301	308	588
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,967	1,314	3,940	2,692
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 879	$ 688	$ 1,821	$ 1,531

Segment and Geographic Inform_4

Segment and Geographic Information - Long-lived Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net and land use rights, net	$ 380,783	$ 331,656
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net and land use rights, net	294,437	248,003
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net and land use rights, net	85,678	83,040
Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net and land use rights, net	$ 668	$ 613

Segment and Geographic Inform_5

Segment and Geographic Information - Narratives (Details)	6 Months Ended
	Dec. 31, 2018Segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

Commitments and Contingencies -

Commitments and Contingencies - Purchase Commitments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Raw materials, wafers, and packaging and testing services puchase commitments
Purchase Commitment, Excluding Long-term Committment [Line Items]
Purchase commitment, amount	$ 48.9	$ 38
Property and equipment purchase commitments
Purchase Commitment, Excluding Long-term Committment [Line Items]
Purchase commitment, amount	$ 78.9	$ 58.3

Commitments and Contingencies_2

Commitments and Contingencies - Contingencies and Indemnities (Details) - USD ($)	Dec. 31, 2018	Jun. 30, 2018
Indemnification Agreement
Loss Contingencies [Line Items]
Indemnifications accrual	$ 0	$ 0