Income Taxes	3 Months Ended
Aug. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In the normal course of business, Cintas provides for uncertain tax positions and the related interest and adjusts its unrecognized tax benefits and accrued interest accordingly. As of August 31, 2018 and May 31, 2018, recorded unrecognized tax benefits were $28.0 million and $26.9 million, respectively, and are included in long-term accrued liabilities on the consolidated condensed balance sheet. The majority of Cintas' operations are in North America. Cintas is required to file federal income tax returns, as well as state income tax returns in a majority of the domestic states and also in certain Canadian provinces. At times, Cintas is subject to audits in these jurisdictions. The audits, by nature, are sometimes complex and can require several years to resolve. The final resolution of any such tax audit could result in either a reduction in Cintas' accruals or an increase in its income tax provision, either of which could have an impact on the consolidated condensed results of operations in any given period. All U.S. federal income tax returns are closed to audit through fiscal 2014. Cintas is currently in various audits in certain foreign jurisdictions and certain domestic states. The years under foreign and domestic state audits cover fiscal years back to 2013. Based on the resolution of the various audits and other potential regulatory developments, it is reasonably possible that the balance of unrecognized tax benefits would not change for the fiscal year ending May 31, 2019. On December 22, 2017, the President signed into legislation the Tax Cuts and Jobs Act (the Tax Act). Among other changes, the Tax Act reduces the U.S. corporate tax rate from 35% to 21% and requires companies to pay a one-time transition tax on earnings of foreign subsidiaries. The Tax Act also includes provisions that are expected to offset some of the benefit of the U.S. corporate tax rate reduction, including the repeal of the deduction for domestic production activities and the expansion of the limitation on the deduction of certain executive compensation. In addition, the Tax Act alters the landscape of taxation of non-U.S. operations and provides immediate deductions for certain new investments, among other provisions. In acknowledgment of the substantial changes incorporated in the Tax Act, and with the timing of the enactment being just weeks before the majority of the provisions became effective, the SEC staff issued Staff Accounting Bulletin (SAB) 118 to provide certain guidance in determining the accounting for income tax effects of the legislation in the accounting period of enactment as well as provide a measurement period within which to finalize and reflect such final effects associated with the Tax Act. During the three months ended August 31, 2018, Cintas recorded an adjustment to the provisional transition tax, net of foreign tax credits, of $3.3 million. Cintas is still revising the transition tax calculation, and this amount is subject to change based on computation of the final fiscal 2018 earnings and profit and the amounts held in cash and cash equivalents at the end of fiscal 2018. Cintas also analyzed the impact of the new provisions under the Tax Act surrounding executive compensation, the foreign derived intangible income deduction and global intangible low-taxed income and determined that the impact was immaterial for the quarter ended August 31, 2018. Cintas’ effective tax rate for continuing operations was 12.0% and 26.5% for the three months ended August 31, 2018 and 2017, respectively. The effective tax rate for both periods was largely impacted by certain discrete items (primarily the tax accounting for stock-based compensation). The three month period ended August 31, 2018 was also impacted by the reduced U.S. corporate tax rate as a result of the enactment of the Tax Act.

Income Taxes

In the normal course of business, Cintas provides for uncertain tax positions and the related interest and adjusts its unrecognized tax benefits and accrued interest accordingly. As of August 31, 2018 and May 31, 2018, recorded unrecognized tax benefits were $28.0 million and $26.9 million, respectively, and are included in long-term accrued liabilities on the consolidated condensed balance sheet.

The majority of Cintas' operations are in North America. Cintas is required to file federal income tax returns, as well as state income tax returns in a majority of the domestic states and also in certain Canadian provinces. At times, Cintas is subject to audits in these jurisdictions. The audits, by nature, are sometimes complex and can require several years to resolve. The final resolution of any such tax audit could result in either a reduction in Cintas' accruals or an increase in its income tax provision, either of which could have an impact on the consolidated condensed results of operations in any given period.

All U.S. federal income tax returns are closed to audit through fiscal 2014. Cintas is currently in various audits in certain foreign jurisdictions and certain domestic states. The years under foreign and domestic state audits cover fiscal years back to 2013. Based on the resolution of the various audits and other potential regulatory developments, it is reasonably possible that the balance of unrecognized tax benefits would not change for the fiscal year ending May 31, 2019.

On December 22, 2017, the President signed into legislation the Tax Cuts and Jobs Act (the Tax Act). Among other changes, the Tax Act reduces the U.S. corporate tax rate from 35% to 21% and requires companies to pay a one-time transition tax on earnings of foreign subsidiaries. The Tax Act also includes provisions that are expected to offset some of the benefit of the U.S. corporate tax rate reduction, including the repeal of the deduction for domestic production activities and the expansion of the limitation on the deduction of certain executive compensation. In addition, the Tax Act alters the landscape of taxation of non-U.S. operations and provides immediate deductions for certain new investments, among other provisions.

In acknowledgment of the substantial changes incorporated in the Tax Act, and with the timing of the enactment being just weeks before the majority of the provisions became effective, the SEC staff issued Staff Accounting Bulletin (SAB) 118 to provide certain guidance in determining the accounting for income tax effects of the legislation in the accounting period of enactment as well as provide a measurement period within which to finalize and reflect such final effects associated with the Tax Act. During the three months ended August 31, 2018, Cintas recorded an adjustment to the provisional transition tax, net of foreign tax credits, of $3.3 million. Cintas is still revising the transition tax calculation, and this amount is subject to change based on computation of the final fiscal 2018 earnings and profit and the amounts held in cash and cash equivalents at the end of fiscal 2018. Cintas also analyzed the impact of the new provisions under the Tax Act surrounding executive compensation, the foreign derived intangible income deduction and global intangible low-taxed income and determined that the impact was immaterial for the quarter ended August 31, 2018.

Cintas’ effective tax rate for continuing operations was 12.0% and 26.5% for the three months ended August 31, 2018 and 2017, respectively. The effective tax rate for both periods was largely impacted by certain discrete items (primarily the tax accounting for stock-based compensation). The three month period ended August 31, 2018 was also impacted by the reduced U.S. corporate tax rate as a result of the enactment of the Tax Act.