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.

No definition available.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Loans and Allowance for Loan Losses - Schedule of Composition of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	$ 11,118,121	$ 9,010,512
Allowance for loan losses	(50,381)	(49,808)	$ (52,233)	$ (47,849)
Net loans	11,067,740	8,960,704
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	2,717,269	1,917,099
Allowance for loan losses	(19,246)	(21,481)	$ (26,347)	$ (20,670)
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	2,167,053	2,087,530
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	1,879,247	1,875,030
Consumer [Member] \| Consumer Credit - Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	507,507	476,439
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	4,354,552	3,130,853
Construction [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	374,306	357,802
Other [Member] \| Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	223,068	230,854
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	3,980,246	2,773,051
Consumer Credit - Auto [Member] \| Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	$ 1,148,672	$ 1,167,737