Basis of Presentation and Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Mar. 31, 2021	Apr. 01, 2020	Mar. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Restructuring and related activities, description	On March 24, 2021, we announced that we will restructure our customer service operations over the next two years to better serve our customers by relocating and streamlining the customer service operation, moving our three regional CSCs to be co-located with regional DSCs, and investing in new technology. Costs associated with this restructure are not expected to be significant.
Retained earnings	$ 14,670,000,000		$ 13,571,000,000
Allowance for credit losses	$ 1,178		$ 727
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date		Apr. 01, 2020
Change in accounting principle, accounting standards update, adopted [true false]		true
Change in accounting principle, accounting standards update, immaterial effect [true false]		false
ASU 2016-13 | Cumulative Effect Period of Adoption Adjustment
Summary Of Significant Accounting Policies [Line Items]
Retained earnings		$ 218,000,000
Allowance for credit losses		292,000,000
Accrued interest		$ 190,000,000
Accounting Standards Update 2018-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Apr. 01, 2020
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	false
Accounting Standards Update 2018-15 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Apr. 01, 2020
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	false
Accounting Standards Update 2019-04 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Apr. 01, 2020
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	false
Accounting Standards Update 2018-17 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Apr. 01, 2020
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	false
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Finance Operations [Member] | California [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	22.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Finance Operations [Member] | Texas [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	11.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Finance Operations [Member] | New York [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	7.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Finance Operations [Member] | New Jersey [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	5.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Voluntary Protection Operations [Member] | California [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	24.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Voluntary Protection Operations [Member] | New York [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	6.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Voluntary Protection Operations [Member] | Maryland [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	5.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Voluntary Protection Operations [Member] | Arizona [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	5.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Voluntary Protection Operations [Member] | Virginia [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Percentage	5.00%