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Activity in Allowance for Loan Losses Based Upon the Method of Evaluating Loan Impairment (Detail) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Financing Receivable, Allowance for Credit Losses [Line Items] |  |
Allowance for Loan Losses, Individually evaluated for impairment | $ 40 |
Allowance for Loan Losses, Collectively evaluated for impairment | 161,100 | $ 158,046
Allowance for Loan Losses | 161,140 |
Mortgage Receivable |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |
Allowance for Loan Losses, Collectively evaluated for impairment | 129,135 | 128,275
Allowance for Loan Losses | 129,135 |
Other loans |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |
Allowance for Loan Losses, Individually evaluated for impairment | 40 |
Allowance for Loan Losses, Collectively evaluated for impairment | 31,965 | $ 29,771
Allowance for Loan Losses | $ 32,005 |

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- Definition A valuation allowance for financing receivables that are expected to be uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
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- Definition The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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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- Definition Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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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- 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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