Derivative Instruments and Hedging Activities - Effect of Derivative Instruments on Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	$ (13,092)	$ (1,407)	$ 2,917
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	(23,227)	(15,656)	1,477
Interest expense \| Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income	(13,092)	(1,407)	95
Other non-interest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income, Discontinued Cash Flow Hedge	0	0	2,822
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	0	0	0
Designated as Hedging Instrument \| Net interest income \| Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	741	0	0
Designated as Hedging Instrument \| Net interest income \| AFS debt securities
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	(741)	0	0
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	(3,830)	3,172	3,545
Not Designated as Hedging Instrument \| Other non-interest income \| Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	(5,482)	2,549	3,409
Not Designated as Hedging Instrument \| Other non-interest income \| Interest rate caps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	0	24	0
Not Designated as Hedging Instrument \| Other non-interest income \| Credit contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	1,531	589	127
Not Designated as Hedging Instrument \| Mortgage banking income \| Residential mortgage loan commitments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Income Recognized in Earnings	$ 121	$ 10	$ 9

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

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No definition available.

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Amount, after tax and before reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from discontinuance of cash flow hedge included in assessment of hedge effectiveness.

+ References

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