Business and Basis of Presentation	12 Months Ended
Sep. 01, 2011
Notes to Financial Statements [Abstract]
Significant accounting policies	Significant Accounting Policies Basis of presentation: We are a global manufacturer and marketer of semiconductor devices, principally DRAM, NAND Flash and NOR Flash memory, as well as other innovative memory technologies, packaging solutions and semiconductor systems for use in leading-edge computing, consumer, networking, embedded and mobile products. In addition, we manufacture CMOS image sensors and other semiconductor products. The accompanying consolidated financial statements include the accounts of Micron Technology, Inc. and its consolidated subsidiaries and have been prepared in accordance with accounting principles generally accepted in the United States of America. Certain reclassifications have been made to prior period amounts to conform to current period presentation. Our fiscal year is the 52 or 53-week period ending on the Thursday closest to August 31. Our fiscal 2011 and 2010 contained 52 weeks and our fiscal 2009 contained 53 weeks. All period references are to our fiscal periods unless otherwise indicated. Use of estimates: The preparation of financial statements and related disclosures in conformity with accounting principles generally accepted in the United States of America requires our management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures. Estimates and judgments are based on historical experience, forecasted events and various other assumptions that we believe to be reasonable under the circumstances. Estimates and judgments may differ under different assumptions or conditions. We evaluate our estimates and judgments on an ongoing basis. Actual results could differ from estimates. Product warranty: We generally provide a limited warranty that our products are in compliance with our specifications existing at the time of delivery. Under our general terms and conditions of sale, liability for certain failures of product during a stated warranty period is usually limited to repair or replacement of defective items or return of, or a credit with respect to, amounts paid for such items. Under certain circumstances, we provide more extensive limited warranty coverage than that provided under our general terms and conditions. Our warranty obligations are not material. Revenue recognition: We recognize product or license revenue when persuasive evidence that a sales arrangement exists, delivery has occurred, the price is fixed or determinable and collectibility is reasonably assured. Since we are unable to estimate returns and changes in market price, and therefore the price is not fixed or determinable, sales made under agreements allowing pricing protection or rights of return (other than for product warranty) are deferred until customers have resold the product. Research and development: Costs related to the conceptual formulation and design of products and processes are expensed as research and development as incurred. Determining when product development is complete requires judgment. Development of a product is deemed complete once the product has been thoroughly reviewed and tested for performance and reliability. Subsequent to product qualification, product costs are valued in inventory. Product design and other research and development costs for NAND Flash and DRAM are shared with our joint venture partners. Amounts receivable from these cost-sharing arrangements are reflected as a reduction of research and development expense. (See "Equity Method Investments" and "Consolidated Variable Interest Entities – NAND Flash joint ventures with Intel" notes.) Stock-based compensation: Stock-based compensation is measured at the grant date, based on the fair value of the award, and is recognized as expense under the straight-line attribution method over the requisite service period. We issue new shares upon the exercise of stock options or conversion of share units. (See "Equity Plans" note.) Stock repurchases: When we repurchase and retire our common stock, any excess of the repurchase price paid over par value is allocated between paid-in capital and retained earnings. Functional currency: The U.S. dollar is the functional currency for all of our consolidated operations. Financial instruments: Cash equivalents include highly liquid short-term investments with original maturities to us of three months or less, readily convertible to known amounts of cash. Investments with original maturities greater than three months and remaining maturities less than one year are included in short-term investments. Investments with remaining maturities greater than one year are included in other noncurrent assets. Securities classified as available-for-sale are stated at market value. The carrying value of investment securities sold is determined using the specific identification method. Derivative and hedging instruments: We use derivative financial instruments, primarily forward contracts, to manage exposures to fluctuating currency exchange rates. We do not use financial instruments for trading or speculative purposes. Derivative instruments are measured at their fair values and recognized as either assets or liabilities. We use forward contracts not designated as hedging instruments to hedge our balance sheet exposures to fluctuations in currency exchange rates. The gain or loss associated with these contracts is recognized in other income (expense). We use forward contracts designated as cash flow hedges to hedge certain forecasted capital expenditures. The effective portion of the gain or loss on these derivatives is included as a component of other comprehensive income (loss) in shareholders' equity. The amount in accumulated other comprehensive income (loss) for these cash flow hedges are reclassified into earnings in the same line items of the consolidated statements of operation and in the same periods in which the underlying transactions affect earnings. Effectiveness is measured by comparing the cumulative change in the fair value of the hedge contract with the cumulative change in the forecasted cash flows of the hedged item. Forward points are excluded in measuring effectiveness and spot rates are used to value both the hedge contract and the hedged item. Any ineffective or excluded portion of the gain or loss is included in other operating income (expense). Inventories: Inventories are stated at the lower of average cost or market value. Cost includes labor, material and overhead costs, including product and process technology costs. Determining market values of inventories involves numerous judgments, including projecting average selling prices and sales volumes for future periods and costs to complete products in work in process inventories. When market values are below costs, we record a charge to cost of goods sold to write down inventories to their estimated market value in advance of when the inventories are actually sold. Inventories are categorized as memory (primarily DRAM and NAND Flash and NOR Flash), imaging and microdisplay products for purposes of determining average cost and market value. The major characteristics considered in determining inventory categories are product type and markets. Product and process technology: Costs incurred to acquire product and process technology or to patent technology are capitalized and amortized on a straight-line basis over periods ranging up to 10 years. We capitalize a portion of costs incurred based on the historical and projected patents issued as a percent of patents we file. Capitalized product and process technology costs are amortized over the shorter of (i) the estimated useful life of the technology, (ii) the patent term or (iii) the term of the technology agreement. Fully-amortized assets are removed from product and process technology and accumulated amortization. Property, plant and equipment: Property, plant and equipment are stated at cost and depreciated using the straight-line method over estimated useful lives of 5 to 30 years for buildings, 2 to 20 years for equipment and 3 to 5 years for software. Assets held for sale are carried at the lower of cost or estimated fair value and are included in other noncurrent assets. When property or equipment is retired or otherwise disposed of, the net book value of the asset is removed and we recognize any gain or loss in our results of operations. We capitalize interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is amortized over the useful lives of the assets. We capitalized interest costs of $12 million, $5 million and $5 million in 2011, 2010 and 2009, respectively.

Significant Accounting Policies

Basis of presentation: We are a global manufacturer and marketer of semiconductor devices, principally DRAM, NAND Flash and NOR Flash memory, as well as other innovative memory technologies, packaging solutions and semiconductor systems for use in leading-edge computing, consumer, networking, embedded and mobile products. In addition, we manufacture CMOS image sensors and other semiconductor products. The accompanying consolidated financial statements include the accounts of Micron Technology, Inc. and its consolidated subsidiaries and have been prepared in accordance with accounting principles generally accepted in the United States of America. Certain reclassifications have been made to prior period amounts to conform to current period presentation.

Our fiscal year is the 52 or 53-week period ending on the Thursday closest to August 31. Our fiscal 2011 and 2010 contained 52 weeks and our fiscal 2009 contained 53 weeks. All period references are to our fiscal periods unless otherwise indicated.

Use of estimates: The preparation of financial statements and related disclosures in conformity with accounting principles generally accepted in the United States of America requires our management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures. Estimates and judgments are based on historical experience, forecasted events and various other assumptions that we believe to be reasonable under the circumstances. Estimates and judgments may differ under different assumptions or conditions. We evaluate our estimates and judgments on an ongoing basis. Actual results could differ from estimates.

Product warranty: We generally provide a limited warranty that our products are in compliance with our specifications existing at the time of delivery. Under our general terms and conditions of sale, liability for certain failures of product during a stated warranty period is usually limited to repair or replacement of defective items or return of, or a credit with respect to, amounts paid for such items. Under certain circumstances, we provide more extensive limited warranty coverage than that provided under our general terms and conditions. Our warranty obligations are not material.

Revenue recognition: We recognize product or license revenue when persuasive evidence that a sales arrangement exists, delivery has occurred, the price is fixed or determinable and collectibility is reasonably assured. Since we are unable to estimate returns and changes in market price, and therefore the price is not fixed or determinable, sales made under agreements allowing pricing protection or rights of return (other than for product warranty) are deferred until customers have resold the product.

Research and development: Costs related to the conceptual formulation and design of products and processes are expensed as research and development as incurred. Determining when product development is complete requires judgment. Development of a product is deemed complete once the product has been thoroughly reviewed and tested for performance and reliability. Subsequent to product qualification, product costs are valued in inventory. Product design and other research and development costs for NAND Flash and DRAM are shared with our joint venture partners. Amounts receivable from these cost-sharing arrangements are reflected as a reduction of research and development expense. (See "Equity Method Investments" and "Consolidated Variable Interest Entities – NAND Flash joint ventures with Intel" notes.)

Stock-based compensation: Stock-based compensation is measured at the grant date, based on the fair value of the award, and is recognized as expense under the straight-line attribution method over the requisite service period. We issue new shares upon the exercise of stock options or conversion of share units. (See "Equity Plans" note.)

Stock repurchases: When we repurchase and retire our common stock, any excess of the repurchase price paid over par value is allocated between paid-in capital and retained earnings.

Functional currency: The U.S. dollar is the functional currency for all of our consolidated operations.

Financial instruments: Cash equivalents include highly liquid short-term investments with original maturities to us of three months or less, readily convertible to known amounts of cash. Investments with original maturities greater than three months and remaining maturities less than one year are included in short-term investments. Investments with remaining maturities greater than one year are included in other noncurrent assets. Securities classified as available-for-sale are stated at market value. The carrying value of investment securities sold is determined using the specific identification method.

Derivative and hedging instruments: We use derivative financial instruments, primarily forward contracts, to manage exposures to fluctuating currency exchange rates. We do not use financial instruments for trading or speculative purposes. Derivative instruments are measured at their fair values and recognized as either assets or liabilities.

We use forward contracts not designated as hedging instruments to hedge our balance sheet exposures to fluctuations in currency exchange rates. The gain or loss associated with these contracts is recognized in other income (expense).

We use forward contracts designated as cash flow hedges to hedge certain forecasted capital expenditures. The effective portion of the gain or loss on these derivatives is included as a component of other comprehensive income (loss) in shareholders' equity. The amount in accumulated other comprehensive income (loss) for these cash flow hedges are reclassified into earnings in the same line items of the consolidated statements of operation and in the same periods in which the underlying transactions affect earnings. Effectiveness is measured by comparing the cumulative change in the fair value of the hedge contract with the cumulative change in the forecasted cash flows of the hedged item. Forward points are excluded in measuring effectiveness and spot rates are used to value both the hedge contract and the hedged item. Any ineffective or excluded portion of the gain or loss is included in other operating income (expense).

Inventories: Inventories are stated at the lower of average cost or market value. Cost includes labor, material and overhead costs, including product and process technology costs. Determining market values of inventories involves numerous judgments, including projecting average selling prices and sales volumes for future periods and costs to complete products in work in process inventories. When market values are below costs, we record a charge to cost of goods sold to write down inventories to their estimated market value in advance of when the inventories are actually sold. Inventories are categorized as memory (primarily DRAM and NAND Flash and NOR Flash), imaging and microdisplay products for purposes of determining average cost and market value. The major characteristics considered in determining inventory categories are product type and markets.

Product and process technology: Costs incurred to acquire product and process technology or to patent technology are capitalized and amortized on a straight-line basis over periods ranging up to 10 years. We capitalize a portion of costs incurred based on the historical and projected patents issued as a percent of patents we file. Capitalized product and process technology costs are amortized over the shorter of (i) the estimated useful life of the technology, (ii) the patent term or (iii) the term of the technology agreement. Fully-amortized assets are removed from product and process technology and accumulated amortization.

Property, plant and equipment: Property, plant and equipment are stated at cost and depreciated using the straight-line method over estimated useful lives of 5 to 30 years for buildings, 2 to 20 years for equipment and 3 to 5 years for software. Assets held for sale are carried at the lower of cost or estimated fair value and are included in other noncurrent assets. When property or equipment is retired or otherwise disposed of, the net book value of the asset is removed and we recognize any gain or loss in our results of operations.

We capitalize interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is amortized over the useful lives of the assets. We capitalized interest costs of $12 million, $5 million and $5 million in 2011, 2010 and 2009, respectively.