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Investment Securities - Additional Information (Details) | 12 Months Ended
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Dec. 31, 2021 USD ($) security | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Summary of Investment Holdings [Line Items] |  |  |
Securities pledged to secure public and other funds, carrying value | $ 2,701,000,000 | $ 2,427,000,000 |
Allowance for credit losses for available-for-sale debt securities | 0 | 0 |
Accrued interest receivable on available-for-sale debt securities | $ 35,500,000 | 27,000,000 |
Number of securities in security portfolio | security | 1,918 |  |
Number of securities in unrealized loss position | security | 357 |  |
Equity securities, at fair value | $ 13,211,000 | 2,547,000 |
Gains on equity securities | 200,000 | 1,400,000 | $ 700,000
Impairments on equity securities without readily determinable fair value | 0 | 117,000 | 0
Downward adjustments on equity securities without readily determinable fair value | 0 | 117,000 | $ 0
Other Assets |  |  |
Summary of Investment Holdings [Line Items] |  |  |
Equity securities without readily determinable fair value | 186,000,000 | $ 105,800,000 |
Indiana |  |  |
Summary of Investment Holdings [Line Items] |  |  |
Investment securities issued by states and political subdivisions, market value | $ 647,600,000 |  |
State and political subdivision investment, equity percentage | 21.50% |  |
Percentage of municipal bonds rated A or better | 97.00% |  |
Percentage of non rated local interest bonds | 3.00% |  |

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- Definition Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 3A -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL120267853-210455 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2A -URI http://asc.fasb.org/extlink&oid=123581744&loc=SL121698322-111563 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL120267856-210455 + Details
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