Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Amount before tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Derivative Instruments and Hedging Activities - Effect of Derivative Financial Instruments on Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	$ 4,062	$ 171	$ 6,830	$ (189)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	2,519	(572)	2,647	(2,166)
Interest Rate Swaps \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	2,519		2,647
Interest Expense \| Interest Rate Swaps \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	3,006	104	5,055	(115)
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	(303)		(175)
Amount of Loss Reclassified from Accumulated OCI into Income		(572)		(2,166)
Other Interest income \| Interest Rate Swaps \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	2,822		2,822
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income (Loss) Recognized in Earnings	1,284	86	1,653	482
Not Designated as Hedging Instrument \| Other Non-interest Income \| Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income (Loss) Recognized in Earnings	1,139	91	1,472	429
Not Designated as Hedging Instrument \| Other Non-interest Income \| Credit Contract
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income (Loss) Recognized in Earnings	156	(6)	119	(5)
Not Designated as Hedging Instrument \| Mortgage Banking Income \| Residential Mortgage Loan Commitments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income (Loss) Recognized in Earnings	$ (11)	$ 1	$ 62	$ 58