Loans Held for Sale - Composition of Loans Held for Sale (Detail) - USD ($) $ in Thousands		9 Months Ended
Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Receivables Held-for-sale [Abstract]
Multi-family loans, at lower of cost or fair value	$ 499,774	$ 499,774		$ 0
Total commercial loans held for sale	499,774	499,774		0
Home equity conversion mortgages, at lower of cost or fair value	1,325	1,325		0
Residential mortgage loans, at fair value	1,755	1,755		1,507
Total consumer loans held for sale	3,080	3,080		1,507
Loans held for sale	502,854	502,854		$ 1,507
Transfer of loan held for investment to held for sale	$ 499,800	$ 499,774	$ 0

Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Commercial, Real Estate1

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- Definition

Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Consumer

+ References

No definition available.

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- Definition

Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Consumer, Home Equity1

+ References

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- Definition

Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage1

+ References

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- Definition

MultiFamilyCommercialLoansHeldForSale

+ References

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- Definition

Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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- References

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- Definition

Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

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