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	Sep. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, Total	$ 31,450	$ 29,700
Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2025	4,514
Loans and financing receivables by origination year, 2024	5,545
Loans and financing receivables by origination year, 2023	4,636
Loans and financing receivables by origination year, 2022	3,439
Loans and financing receivables by origination year, 2021	2,860
Loans and financing receivables by origination year, Prior	9,649
Loans and financing receivables by origination year, Total	30,643
Performing [Member] \| Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2025	4,512
Loans and financing receivables by origination year, 2024	5,527
Loans and financing receivables by origination year, 2023	4,611
Loans and financing receivables by origination year, 2022	3,421
Loans and financing receivables by origination year, 2021	2,845
Loans and financing receivables by origination year, Prior	9,590
Loans and financing receivables by origination year, Total	30,506
Non-Performing [Member] \| Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2025	2
Loans and financing receivables by origination year, 2024	18
Loans and financing receivables by origination year, 2023	25
Loans and financing receivables by origination year, 2022	18
Loans and financing receivables by origination year, 2021	15
Loans and financing receivables by origination year, Prior	59
Loans and financing receivables by origination year, Total	$ 137

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
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-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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