Derivative Financial Instruments (Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Designated as Hedging Instrument [Member] \| Financial Institution Counterparties Loan Lease Interest Rate Swaps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 10,941	$ 13,679
Estimated Fair Value	207	242
Designated as Hedging Instrument [Member] \| Financial Institution Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	3,885	11,147
Estimated Fair Value	(199)	(593)
Not Designated as Hedging Instrument [Member] \| Financial Institution Counterparties Loan Lease Interest Rate Swaps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	496,887	430,449
Estimated Fair Value	2,384	1,418
Not Designated as Hedging Instrument [Member] \| Financial Institution Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	691,143	541,496
Estimated Fair Value	(8,921)	(12,820)
Not Designated as Hedging Instrument [Member] \| Financial Institution Counterparties Loan Lease Interest Rate Caps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	122,791	114,619
Estimated Fair Value	509	480
Not Designated as Hedging Instrument [Member] \| Customer Counterparties Loan Lease Interest Rate Swaps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	691,143	541,496
Estimated Fair Value	16,706	17,882
Not Designated as Hedging Instrument [Member] \| Customer Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	496,887	430,449
Estimated Fair Value	(8,891)	(4,861)
Not Designated as Hedging Instrument [Member] \| Customer Counterparties Loan Lease Interest Rate Caps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	122,791	114,619
Estimated Fair Value	$ (509)	$ (480)

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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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.

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