Leases Lessor Maturity Table (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 31, 2020
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable		$ 370
MPC
Lessor, Lease, Description [Line Items]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Current Year	$ 39
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	157
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	157
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three	158
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four	158
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five	473
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	1,142
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	723
Sales-type Lease, Lease Receivable	419
Third Party [Member]
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable	$ 1

Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Current Year

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919391-209981

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of undiscounted lease receivable in excess of discounted receivable for sales-type and direct financing leases.

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Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919379-209981

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