Debt and Credit Facilities - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Mar. 31, 2021	Apr. 30, 2021	Jul. 31, 2020	Mar. 31, 2020
364 Day Credit Agreement Expiring 2022 [Member]
Line Of Credit Facility [Line Items]
Initiation date	2020-11
Maximum borrowing capacity	$ 5,000,000,000.0
Credit facilities amount outstanding			$ 0			$ 0
Three Year Agreement Expiring 2023 [Member]
Line Of Credit Facility [Line Items]
Initiation date		2019-11
Maximum borrowing capacity		$ 5,000,000,000.0
Credit facilities amount outstanding			0			0
Five Year Agreement Expiring 2025 [Member]
Line Of Credit Facility [Line Items]
Initiation date		2019-11
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					$ 6,500,000,000
Credit facilities amount outstanding			3,200,000,000
Total Committed Bank Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			4,400,000,000
Credit facilities amount outstanding			0			$ 0
Committed Bank Credit Facility Expiring 2022 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			2,300,000,000
Committed Bank Credit Facility Expiring 2023 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			1,800,000,000
Committed Bank Credit Facility Expiring 2024 [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			300,000,000
Three Year Revolving Credit Facility [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			5,000,000,000.0
Credit facility, repayment of principal and accrued interest			$ 3,000,000,000.0
Credit facilities interest rate			1.86%
Three Year Revolving Credit Facility Expiring 2025 [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Maximum borrowing capacity				$ 5,000,000,000.0