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Activity in Allowance for Loan Losses Based Upon the Method of Evaluating Loan Impairment (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Collectively evaluated for impairment	$ 159,655	$ 158,046
Mortgage Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Collectively evaluated for impairment	128,816	128,275
Other loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Collectively evaluated for impairment	$ 30,839	$ 29,771

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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X

- 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.

+ Details

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- Details

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- Details

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