Loans and finance receivables - Summary of performing and non-performing home loans before discounts and allowances by year of loan origination (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, Total	$ 20,800	$ 20,436
Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2021	1,744
Loans and financing receivables by origination year, 2020	3,444
Loans and financing receivables by origination year, 2019	2,466
Loans and financing receivables by origination year, 2018	1,879
Loans and financing receivables by origination year, 2017	1,392
Loans and financing receivables by origination year, Prior	7,776
Loans and financing receivables by origination year, Total	18,701
Performing [Member] | Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2021	1,742
Loans and financing receivables by origination year, 2020	3,443
Loans and financing receivables by origination year, 2019	2,460
Loans and financing receivables by origination year, 2018	1,872
Loans and financing receivables by origination year, 2017	1,386
Loans and financing receivables by origination year, Prior	7,726
Loans and financing receivables by origination year, Total	18,629
Non-Performing [Member] | Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2021	2
Loans and financing receivables by origination year, 2020	1
Loans and financing receivables by origination year, 2019	6
Loans and financing receivables by origination year, 2018	7
Loans and financing receivables by origination year, 2017	6
Loans and financing receivables by origination year, Prior	50
Loans and financing receivables by origination year, Total	$ 72