Derivatives - Summary of Derivatives Outstanding Included in Other Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	$ 1,384,183
Derivative assets, Fair value	15,352
Derivative liabilities, Notional	1,604,314
Derivative liabilities, Fair value	16,839
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	0
Derivative assets, Fair value	0
Derivative liabilities, Notional	250,000
Derivative liabilities, Fair value	1,483
Designated as Hedging Instrument \| Interest rate contracts - pay fixed, receive floating
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	0
Derivative assets, Fair value	0
Derivative liabilities, Notional	250,000
Derivative liabilities, Fair value	1,483
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	1,384,183	$ 1,233,004
Derivative assets, Fair value	15,352	11,833
Derivative liabilities, Notional	1,354,314	1,233,004
Derivative liabilities, Fair value	15,356	11,833
Not Designated as Hedging Instrument \| Interest rate contracts - pay floating, receive fixed
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	352,736	757,887
Derivative assets, Fair value	7,232	11,678
Derivative liabilities, Notional	904,363	380,233
Derivative liabilities, Fair value	15,009	4,180
Not Designated as Hedging Instrument \| Interest rate contracts - pay fixed, receive floating
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	904,363	380,233
Derivative assets, Fair value	7,777	0
Derivative liabilities, Notional	352,736	757,887
Derivative liabilities, Fair value	0	7,498
Not Designated as Hedging Instrument \| Interest rate caps purchased
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	94,765	94,884
Derivative assets, Fair value	343	155
Derivative liabilities, Notional	0	0
Derivative liabilities, Fair value	0	0
Not Designated as Hedging Instrument \| Interest rate caps sold
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	0	0
Derivative assets, Fair value	0	0
Derivative liabilities, Notional	94,765	94,884
Derivative liabilities, Fair value	343	$ 155
Not Designated as Hedging Instrument \| Risk participation agreements
Derivatives, Fair Value [Line Items]
Derivative assets, Notional	32,319
Derivative assets, Fair value	0
Derivative liabilities, Notional	2,450
Derivative liabilities, Fair value	$ 4

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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-Publisher FASB
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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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

Nominal or face amount used to calculate payments on the derivative liability.

+ References

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-Publisher FASB
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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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