Loans Held for Sale - Composition of Loans Held for Sale (Detail) - USD ($) $ in Thousands			6 Months Ended
Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Receivables Held-for-sale [Abstract]
Mortgage warehouse loans, at fair value			$ 1,930,738		$ 1,793,408
Multi-family loans at lower of cost or fair value			0		144,191
Total commercial loans held for sale			1,930,738		1,937,599
Residential mortgage loans, at fair value			1,043		1,886
Loans held for sale			$ 1,931,781		$ 1,939,485
Loans held for sale, average life from purchase to sale			20 days
Transfer of loans held for sale to held for investment	$ 129,700		$ 129,691	$ 0
Transfer of loans held for investment to loans held for sale		$ 150,600	$ 0	$ 150,758

Loans Held For Sale Average Life From Purchase To Sale

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Mortgage Warehouse Loans Held For Sale

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- Definition

MultiFamilyCommercialLoansHeldForSale

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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Amount, after allowance for bad debt, of commercial mortgage 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.

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Amount, after allowance for bad debt, of mortgage 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.

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Value of loans held-for-sale transferred to loans held in the entity's portfolio in noncash 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 50
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Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

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