Debt and Credit Facilities - Additional Information (Details) - USD ($)	Dec. 31, 2021	Mar. 31, 2021
364 Day Credit Agreement Expiring 2023 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	$ 5,000,000,000.0
Credit facilities amount outstanding	0	$ 0
Three Year Agreement Expiring 2025 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	5,000,000,000.0
Credit facilities amount outstanding	0	0
Five Year Agreement Expiring 2027 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	5,000,000,000.0
Credit facilities amount outstanding	0	0
Revolving Securitization Facility [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	7,000,000,000.0
Credit facilities amount outstanding	3,700,000,000	3,200,000,000
Total Committed Bank Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	4,600,000,000
Credit facilities amount outstanding	0	0
Committed Bank Credit Facility Expiring 2022 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	350,000,000
Committed Bank Credit Facility Expiring 2023 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	2,200,000,000
Committed Bank Credit Facility Expiring 2024 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	300,000,000
Committed Bank Credit Facility Expiring 2025 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	1,700,000,000
Three Year Revolving Credit Facility Expiring 2025 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	5,000,000,000.0
Credit facilities amount outstanding	$ 0	$ 0