NOTES PAYABLE, LONG-TERM DEBT AND AVAILABLE CREDIT FACILITIES (Schedule of Committed and Available Credit Facilities) (Details) - USD ($) $ in Millions	May 31, 2016	Mar. 31, 2018
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		$ 10,880
Line of Credit Facility, Remaining Borrowing Capacity		6,380
Revolving Credit Facility [Member] | Five Year Competitive Advance and Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		5,000
Line of Credit Facility, Remaining Borrowing Capacity		5,000
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2019 [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		100
Line of Credit Facility, Remaining Borrowing Capacity		100
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2020, Facility One [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		100
Line of Credit Facility, Remaining Borrowing Capacity		100
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2020, Facility Two [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		280
Line of Credit Facility, Remaining Borrowing Capacity		280
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2020, Facility Three [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		100
Line of Credit Facility, Remaining Borrowing Capacity		100
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2020, Facility Four [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		100
Line of Credit Facility, Remaining Borrowing Capacity		100
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due March 2020, Facility Five [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		200
Line of Credit Facility, Remaining Borrowing Capacity		200
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due May 2018 [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		200
Line of Credit Facility, Remaining Borrowing Capacity		200
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due July 2018 [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		200
Line of Credit Facility, Remaining Borrowing Capacity		200
Revolving Credit Facility [Member] | Bilateral Revolving Credit Facility, Due August 2018 [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		100
Line of Credit Facility, Remaining Borrowing Capacity		100
Term Loan Facility [Domain] | DCC Term Loan Facility [Domain]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit		4,500
Line of Credit Facility, Remaining Borrowing Capacity		$ 0
Proceeds from Lines of Credit	$ 4,500