Loans and finance receivables - Narrative (Detail) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provisions for loan losses	$ 109,000,000	$ 109,000,000
Loan charge-offs, net of recoveries	$ 103,000,000	$ 106,000,000
Percent of manufactured housing loan balances evaluated collectively for impairment	98.00%
Percent of loan balances considered to be performing	99.00%
Percent of loan balances considered to be current as to payment status	96.00%
Seritage Growth Properties [Member] \| Term Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loan facility amount			$ 2,000,000,000.0
Expiration date of term loan			Jul. 31, 2023
Outstanding loan balance	$ 1,600,000,000		$ 1,600,000,000

Percent of manufactured housing loan balances evaluated collectively for impairment.

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- Definition

Percent of loan balances that are performing.

+ References

No definition available.

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- Definition

Percent of loan balances that are current as to payment status.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Amount, after recoveries, of loans and leases that have been written-off.

+ References

No definition available.

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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