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Employee Benefit Plans - Narrative (Details) - USD ($) | 12 Months Ended
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May 31, 2017 | May 31, 2016 | May 31, 2015
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated contribution to pension plan | $ 0 |  |
Accrued benefit liability | 28,000,000 |  |
Unrecognized net actuarial loss | 1,200,000 |  |
Fair value of plan assets | 59,396,000 | $ 0 |
Projected benefit obligation | 87,387,000 | 0 |
Net periodic benefit cost | $ (28,000) |  |
Expected return on plan assets (as a percent) | 5.40% |  |
Supplemental Executive Retirement Plan (SERP) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | $ 6,900,000 | 6,600,000 | $ 6,100,000
Domestic Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Required years of service for plan eligibility (years) | 1 year |  |
Employer contributions | $ 47,500,000 | 43,100,000 | 38,400,000
Deferred Profit Sharing Plan (DPSP) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | 1,800,000 | 1,600,000 | $ 1,500,000
Pension Plan of Immaterial Acquisitions |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 7,100,000 | 6,500,000 |
Projected benefit obligation | 7,500,000 | 7,700,000 |
Net periodic benefit cost | $ 100,000 | $ 100,000 |

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- Definition Amount of liability, recognized in statement of financial position, for defined benefit pension plan. Excludes other postretirement benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(15)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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