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Allowance for Loan Losses - Additional Information (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Minimum period interest and principal of loans past due considered nonperforming (in days) |  | 90 days |
Threshold for evaluation for impairment of substandard and nonaccrual commercial loans |  | $ 500 |
Increase in impaired loans |  | 25,800 |
Impaired financing receivables |  | 75,337 | $ 49,506
Loans receivable, net |  | 7,142,408 | 5,949,019
Modified loan | [1] | 32,206 | 11,384
Commercial |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Loans recorded investment |  | 5,512,796 | 4,672,445
Modified loan |  | 20,200 |
Commercial | Substandard |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Increase (decrease) in loans |  | (28,500) |
Loans recorded investment |  | 152,651 | 181,192
Commercial | Special mention |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Increase (decrease) in loans |  | 16,500 |
Loans recorded investment |  | 103,878 | 87,344
DNB |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Loans receivable, net |  | $ 899,300 | $ 909,000
[1] | Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

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- Definition Minimum amount over which evaluation for impairment of substandard and nonaccrual commercial loans are made. + References No definition available. + Details
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- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
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