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Allowance for Credit Losses and Credit Quality of Loans (Details) - USD ($) $ in Thousands | 6 Months Ended |  |
--- | --- | --- | ---
Jun. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019
Allowance for Credit Losses [Abstract] |  |  |  |
Allowance for credit losses | [1] | $ 113,500 |  |
Retained earnings |  | 703,322 |  | $ 696,214
ASU 2016-13 [Member] |  |  |  |
Allowance for Credit Losses [Abstract] |  |  |  |
Allowance for credit losses |  | 113,500 | $ 100,000 | 75,999
AIR on loans |  | $ 26,800 |  |
ASU 2016-13 [Member] | Minimum [Member] |  |  |  |
Allowance for Credit Losses [Abstract] |  |  |  |
Write-off of uncollectible interest period |  | 120 days |  |
ASU 2016-13 [Member] | Accrued Interest Receivable [Member] |  |  |  |
Allowance for Credit Losses [Abstract] |  |  |  |
Allowance for credit losses |  | $ 1,100 |  |
ASU 2016-13 [Member] | Cumulative Effect Adjustment for ASU Implementation [Member] |  |  |  |
Allowance for Credit Losses [Abstract] |  |  |  |
Allowance for credit losses |  |  |  | 3,000
Retained earnings |  |  |  | (4,300)
Deferred tax asset |  |  |  | (1,500)
ASU 2016-13 [Member] | Cumulative Effect Adjustment for ASU Implementation [Member] | Loans [Member] |  |  |  |
Allowance for Credit Losses [Abstract] |  |  |  |
Allowance for credit losses |  |  |  | 3,000
Retained earnings |  |  |  | (2,300)
Deferred tax asset |  |  |  | $ 700
[1] | Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.

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- Definition The write-off period of uncollectible interest of delinquent loans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, with jurisdictional netting. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e31931-109318 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e31917-109318 + Details
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- Definition Amount, after allowance for credit loss, of accrued interest on financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3A -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL120267960-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL120267845-210446 + Details
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- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. + 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 (c)(1) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
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