Allowance for Loan Losses - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 6,204,136	$ 5,949,019
Loans considered nonperforming (in days)	90 days
Threshold for evaluation for impairment of substandard and nonaccrual commercial loans	$ 500
Commercial \| Substandard
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in loans	(46,200)
Loans	135,000	181,200
Commercial \| Special Mention
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in loans	23,400
Loans	$ 110,700	$ 87,300

Minimum amount over which evaluation for impairment of substandard and nonaccrual commercial loans are made.

No definition available.

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- Definition

Period interest and principal of loan due treated as loans considered nonperforming.

+ References

No definition available.

+ 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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- Definition

The increase (decrease) during the reporting period in outstanding loans including accrued interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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- Definition

Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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