Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	May 27, 2018
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all investments purchased with an original maturity of three months or less to be cash equivalents.
Inventories	Inventories All inventories in the United States other than grain are valued at the lower of cost, using the last-in, first-out (LIFO) method, or market. Grain inventories are valued at net realizable value, and all related cash contracts and derivatives are valued at fair value, with all net changes in value recorded in earnings currently. Inventories outside of the United States are generally valued at the lower of cost, using the first-in, first-out (FIFO) method, or net realizable value. Shipping costs associated with the distribution of finished product to our customers are recorded as cost of sales, and are recognized when the related finished product is shipped to and accepted by the customer.
Land, Buildings, Equipment, and Depreciation	Land, Buildings, Equipment, and Depreciation Land is recorded at historical cost. Buildings and equipment, including capitalized interest and internal engineering costs, are recorded at cost and depreciated over estimated useful lives, primarily using the straight-line method. Ordinary maintenance and repairs are charged to cost of sales. Buildings are usually depreciated over 40 years, and equipment, furniture, and software are usually depreciated over 3 to 10 years. Fully depreciated assets are retained in buildings and equipment until disposal. When an item is sold or retired, the accounts are relieved of its cost and related accumulated depreciation and the resulting gains and losses, if any, are recognized in earnings. As of May 27, 2018, assets held for sale were insignificant. Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows from the operation and disposition of the asset group are less than the carrying amount of the asset group. Asset groups have identifiable cash flows and are largely independent of other asset groups. Measurement of an impairment loss would be based on the excess of the carrying amount of the asset group over its fair value. Fair value is measured using a discounted cash flow model or independent appraisals, as appropriate.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill is not subject to amortization and is tested for impairment annually and whenever events or changes in circumstances indicate that impairment may have occurred. In fiscal 2016, we changed the date of our annual goodwill and indefinite-lived intangible asset impairment assessment from the first day of the third quarter to the first day of the second quarter to more closely align with the timing of our annual long-range planning process. Impairment testing is performed for each of our reporting units. We compare the carrying value of a reporting unit, including goodwill, to the fair value of the unit. Carrying value is based on the assets and liabilities associated with the operations of that reporting unit, which often requires allocation of shared or corporate items among reporting units. If the carrying amount of a reporting unit exceeds its fair value, impairment has occurred. We recognize an impairment charge for the amount by which the carrying amount of the reporting unit exceeds its fair value up to the total amount of goodwill allocated to the reporting unit. Our estimates of fair value are determined based on a discounted cash flow model. Growth rates for sales and profits are determined using inputs from our long-range planning process. We also make estimates of discount rates, perpetuity growth assumptions, market comparables, and other factors. We evaluate the useful lives of our other intangible assets, mainly brands, to determine if they are finite or indefinite-lived. Reaching a determination on useful life requires significant judgments and assumptions regarding the future effects of obsolescence, demand, competition, other economic factors (such as the stability of the industry, known technological advances, legislative action that results in an uncertain or changing regulatory environment, and expected changes in distribution channels), the level of required maintenance expenditures, and the expected lives of other related groups of assets. Intangible assets that are deemed to have definite lives are amortized on a straight-line basis, over their useful lives, generally ranging from 4 to 30 years. Our indefinite-lived intangible assets, mainly intangible assets primarily associated with the Blue Buffalo, Pillsbury, Totino’s, Progresso, Yoplait, Old El Paso, Yoki, Häagen-Dazs, and Annie’s brands, are also tested for impairment annually and whenever events or changes in circumstances indicate that their carrying value may not be recoverable. Our estimate of the fair value of the brands is based on a discounted cash flow model using inputs which included projected revenues from our long-range plan, assumed royalty rates that could be payable if we did not own the brands, and a discount rate. Our finite-lived intangible assets, primarily acquired franchise agreements and customer relationships, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows from the operation and disposition of the asset are less than the carrying amount of the asset. Assets generally have identifiable cash flows and are largely independent of other assets. Measurement of an impairment loss would be based on the excess of the carrying amount of the asset over its fair value. Fair value is measured using a discounted cash flow model or other similar valuation model, as appropriate.
Investments in Unconsolidated Joint Ventures and Redeemable Interest	Investments in Unconsolidated Joint Ventures Our investments in companies over which we have the ability to exercise significant influence are stated at cost plus our share of undistributed earnings or losses. We receive royalty income from certain joint ventures, incur various expenses (primarily research and development), and record the tax impact of certain joint venture operations that are structured as partnerships. In addition, we make advances to our joint ventures in the form of loans or capital investments. We also sell certain raw materials, semi-finished goods, and finished goods to the joint ventures, generally at market prices. In addition, we assess our investments in our joint ventures if we have reason to believe an impairment may have occurred including, but not limited to, as a result of ongoing operating losses, projected decreases in earnings, increases in the weighted average cost of capital, or significant business disruptions. The significant assumptions used to estimate fair value include revenue growth and profitability, royalty rates, capital spending, depreciation and taxes, foreign currency exchange rates, and a discount rate. By their nature, these projections and assumptions are uncertain. If we were to determine the current fair value of our investment was less than the carrying value of the investment, then we would assess if the shortfall was of a temporary or permanent nature and write down the investment to its fair value if we concluded the impairment is other than temporary. Redeemable Interest We have a 51 percent controlling interest in Yoplait SAS, a consolidated entity. Sodiaal International (Sodiaal) holds the remaining 49 percent interest in Yoplait SAS. Sodiaal has the ability to put all or a portion of its redeemable interest to us at fair value once per year, up to three times before December 2024. This put option requires us to classify Sodiaal’s interest as a redeemable interest outside of equity on our Consolidated Balance Sheets for as long as the put is exercisable by Sodiaal. When the put is no longer exercisable, the redeemable interest will be reclassified to noncontrolling interests on our Consolidated Balance Sheets. We adjust the value of the redeemable interest through additional paid-in capital on our Consolidated Balance Sheets quarterly to the redeemable interest’s redemption value, which approximates its fair value. During the second quarter of fiscal 2018, we adjusted the redeemable interest’s redemption value based on a discounted cash flow model. The significant assumptions used to estimate the redemption value include projected revenue growth and profitability from our long-range plan, capital spending, depreciation, taxes, foreign currency exchange rates, and a discount rate.
Revenue Recognition	Revenue Recognition We recognize sales revenue when the shipment is accepted by our customer. Sales include shipping and handling charges billed to the customer and are reported net of consumer coupon redemption, trade promotion and other costs, including estimated allowances for returns, unsalable product, and prompt pay discounts. Sales, use, value-added, and other excise taxes are not recognized in revenue. Coupons are recorded when distributed, based on estimated redemption rates. Trade promotions are recorded based on estimated participation and performance levels for offered programs at the time of sale. We generally do not allow a right of return. However, on a limited case-by-case basis with prior approval, we may allow customers to return product. In limited circumstances, product returned in saleable condition is resold to other customers or outlets. Receivables from customers generally do not bear interest. Terms and collection patterns vary around the world and by channel. The allowance for doubtful accounts represents our estimate of probable non-payments and credit losses in our existing receivables, as determined based on a review of past due balances and other specific account data. Account balances are written off against the allowance when we deem the amount is uncollectible.
Environmental	Environmental Environmental costs relating to existing conditions caused by past operations that do not contribute to current or future revenues are expensed. Liabilities for anticipated remediation costs are recorded on an undiscounted basis when they are probable and reasonably estimable, generally no later than the completion of feasibility studies or our commitment to a plan of action.
Advertising Production Costs	Advertising Production Costs We expense the production costs of advertising the first time that the advertising takes place.
Research and Development	Research and Development All expenditures for research and development (R&D) are charged against earnings in the period incurred. R&D includes expenditures for new product and manufacturing process innovation, and the annual expenditures are comprised primarily of internal salaries, wages, consulting, and supplies attributable to R&D activities. Other costs include depreciation and maintenance of research facilities, including assets at facilities that are engaged in pilot plant activities.
Foreign Currency Translation	Foreign Currency Translation For all significant foreign operations, the functional currency is the local currency. Assets and liabilities of these operations are translated at the period-end exchange rates. Income statement accounts are translated using the average exchange rates prevailing during the period. Translation adjustments are reflected within accumulated other comprehensive loss (AOCI) in stockholders’ equity. Gains and losses from foreign currency transactions are included in net earnings for the period, except for gains and losses on investments in subsidiaries for which settlement is not planned for the foreseeable future and foreign exchange gains and losses on instruments designated as net investment hedges. These gains and losses are recorded in AOCI.
Derivative Instruments	Derivative Instruments All derivatives are recognized on our Consolidated Balance Sheets at fair value based on quoted market prices or our estimate of their fair value, and are recorded in either current or noncurrent assets or liabilities based on their maturity. Changes in the fair values of derivatives are recorded in net earnings or other comprehensive income, based on whether the instrument is designated and effective as a hedge transaction and, if so, the type of hedge transaction. Gains or losses on derivative instruments reported in AOCI are reclassified to earnings in the period the hedged item affects earnings. If the underlying hedged transaction ceases to exist, any associated amounts reported in AOCI are reclassified to earnings at that time. Any ineffectiveness is recognized in earnings in the current period.
Stock-based Compensation	Stock-based Compensation We generally measure compensation expense for grants of restricted stock units using the value of a share of our stock on the date of grant. We estimate the value of stock option grants using a Black-Scholes valuation model. Stock-based compensation is recognized straight line over the vesting period. Our stock-based compensation expense is recorded in selling, general and administrative (SG&A) expenses and cost of sales in our Consolidated Statements of Earnings and allocated to each reportable segment in our segment results. Certain equity-based compensation plans contain provisions that accelerate vesting of awards upon retirement, termination, or death of eligible employees and directors. We consider a stock-based award to be vested when the employee’s retention of the award is no longer contingent on providing subsequent service. Accordingly, the related compensation cost is generally recognized immediately for awards granted to retirement-eligible individuals or over the period from the grant date to the date retirement eligibility is achieved, if less than the stated vesting period. We report the benefits of tax deductions in excess of recognized compensation cost as an operating cash flow.
Defined Benefit Pension, Other Postretirement Benefit, and Postemployment Benefit Plans	Defined Benefit Pension, Other Postretirement Benefit, and Postemployment Benefit Plans We sponsor several domestic and foreign defined benefit plans to provide pension, health care, and other welfare benefits to retired employees. Under certain circumstances, we also provide accruable benefits, primarily severance, to former or inactive employees in the United States, Canada, and Mexico. We recognize an obligation for any of these benefits that vest or accumulate with service. Postemployment benefits that do not vest or accumulate with service (such as severance based solely on annual pay rather than years of service) are charged to expense when incurred. Our postemployment benefit plans are unfunded. We recognize the underfunded or overfunded status of a defined benefit pension plan as an asset or liability and recognize changes in the funded status in the year in which the changes occur through AOCI. In fiscal 2018, we approved an amendment to reorganize the U.S. qualified defined benefit pension plans and the supplemental pension plans that resulted in the spinoff of a portion of the General Mills Pension Plan (the Plan) and the 2005 Supplemental Retirement Plan and the Supplemental Retirement Plan (Grandfathered) (together, the Supplemental Plans) into new plans effective May 31, 2018. The benefits offered to the plans’ participants were unchanged. The result of the reorganization was the creation of the General Mills Pension Plan I (Plan I) and the 2005 Supplemental Retirement Plan I and the Supplemental Retirement Plan I (Grandfathered) (together, the Supplemental Plans I). The reorganization was made to facilitate a targeted investment strategy over time and to provide additional flexibility in evaluating opportunities to reduce risk and volatility. Actuarial gains and losses associated with the Plan and the Supplemental Plans are amortized over the average remaining service period of the active participants. Actuarial gains and losses associated with the Plan I and the Supplemental Plans I are amortized over the average remaining life of the participants. Please refer to Note 13 for a description of our defined benefit pension, other postretirement benefit, and postemployment benefit plans.
Use of Estimates	Use of Estimates Preparing our Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. These estimates include our accounting for promotional expenditures, valuation of long-lived assets, intangible assets, redeemable interest, stock-based compensation, income taxes, and defined benefit pension, other postretirement benefit and postemployment benefit plans. Actual results could differ from our estimates.
Other New Accounting Standards	Other New Accounting Standards In the third quarter of fiscal 2018, we adopted new accounting requirements that codify Securities and Exchange Commission (SEC) Staff Accounting Bulletin (SAB) No. 118, as it relates to allowing for recognition of provisional amounts related to the U.S. Tax Cuts and Jobs Act (TCJA) in the event that the accounting is not complete and a reasonable estimate can be made. Where necessary information is not available, prepared, or analyzed to determine a reasonable estimate, no provisional amount should be recorded. The guidance allows for a measurement period of up to one year from the enactment date to finalize the accounting related to the TCJA. In the third quarter of fiscal 2018, we adopted new accounting requirements that provide the option to reclassify stranded income tax effects resulting from the TCJA from AOCI to retained earnings. We elected to reclassify the stranded income tax effects of the TCJA of $329.4 million from AOCI to retained earnings. This reclassification consists of deferred taxes originally recorded in AOCI that exceed the newly enacted federal corporate tax rate. The new accounting requirements allow for adjustments to reclassification amounts in subsequent periods as a result of changes to the provisional amounts recorded. In the first quarter of fiscal 2018, we adopted new requirements for the accounting and presentation of stock-based payments. The adoption of this guidance resulted in the prospective recognition of realized windfall and shortfall tax benefits related to the exercise or vesting of stock-based awards in our Consolidated Statements of Earnings instead of additional paid-in capital within our Consolidated Balance Sheets. We recognized a windfall tax benefit in income tax expense in our Consolidated Statements of Earnings of $25.2 million in fiscal 2018. We retrospectively adopted the guidance related to reclassification of realized windfall tax benefits in our Consolidated Statements of Cash Flows. This resulted in reclassifications of $25.2 million, $64.1 million, and $94.1 million of cash provided by financing activities to operating activities for fiscal 2018, fiscal 2017, and fiscal 2016, respectively. Additionally, we retrospectively adopted the guidance related to reclassification of employee tax withholdings in our Consolidated Statements of Cash Flows. This resulted in reclassifications of $26.8 million, $37.8 million, and $40.3 million of cash used by operating activities to financing activities for fiscal 2018, fiscal 2017, and fiscal 2016, respectively. Stock-based compensation expense continues to reflect estimated forfeitures. In the first quarter of fiscal 2018, we adopted new accounting requirements which permit reporting entities to measure a goodwill impairment loss by the amount by which a reporting unit’s carrying value exceeds the reporting unit’s fair value. Previously, goodwill impairment losses were required to be measured by determining the implied fair value of goodwill. Our annual goodwill impairment test was performed as of the first day of the second quarter of fiscal 2018, and the adoption of this guidance did not impact our results of operations or financial position. In the first quarter of fiscal 2017, we adopted new accounting requirements for the presentation of certain investments using the net asset value, providing a practical expedient to exclude such investments from categorization within the fair value hierarchy and separate disclosure. We adopted the guidance retrospectively and restated the fiscal 2016 fair value of plan asset tables in Note 13. The adoption of this guidance did not impact our results of operations or financial position. In the first quarter of fiscal 2017, we adopted new accounting requirements which permit reporting entities with a fiscal year-end that does not coincide with a month-end to apply a practical expedient that permits the entity to measure defined benefit plan assets and obligations using the month-end that is closest to the entity’s fiscal year-end and apply such practical expedient consistently to all plans. The adoption of this guidance did not have a material impact on our results of operations or financial position. In the fourth quarter of fiscal 2016, we adopted new accounting requirements for the presentation of deferred tax assets and liabilities, requiring noncurrent classification for all deferred tax assets and liabilities on the statement of financial position. This presentation change has been implemented retroactively. The adoption of this guidance did not have a material impact on our financial position. In the first quarter of fiscal 2016, we adopted new accounting requirements for the classification of debt issuance costs presented in the balance sheet as a direct reduction from the carrying amount of the debt liability. This presentation change has been implemented retroactively. The adoption of this guidance did not have a material impact on our financial position.