Subordinated Deferrable Debt Subordinated Deferrable Debt Outstanding (Details) - USD ($) $ in Thousands	Nov. 30, 2019	May 31, 2019
Subordinated Deferrable Debt
Subordinated Debt	$ 986,026	$ 986,020
4.75 percent due 2043
Subordinated Deferrable Debt
Subordinated Debt	$ 400,000	$ 400,000
Debt Instrument, Interest Rate, Stated Percentage	4.75%	4.75%
5.25 Percent Due 2046
Subordinated Deferrable Debt
Subordinated Debt	$ 350,000	$ 350,000
Debt Instrument, Interest Rate, Stated Percentage	5.25%	5.25%
5.50 Percent Due 2064
Subordinated Deferrable Debt
Subordinated Debt	$ 250,000	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%	5.50%
Subordinated Debt
Subordinated Deferrable Debt
Debt issuance costs	$ 13,974	$ 13,980

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

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