Derivative Instruments and Hedging Activities - Derivatives Not Designated as Hedging Instruments (Detail) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative, Notional Amount	$ 120,384		$ 120,384		$ 73,995
Derivative Assets, Fair Value	2,432		2,432		1,089
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	510		510		102
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	444	$ (7)	935	$ 386
Interest Rate Locks with Customers [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative, Notional Amount	57,601		57,601		34,450
Interest Rate Locks with Customers [Member] | Mortgage Banking Activities [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	711	(312)	1,343	137
Interest Rate Locks with Customers [Member] | Other Assets [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Assets, Fair Value	2,432		2,432		1,089
Interest Rate Locks with Customers [Member] | Other Liabilities [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0		0		0
Forward Loan Sale Commitments [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative, Notional Amount	62,783		62,783		39,545
Forward Loan Sale Commitments [Member] | Mortgage Banking Activities [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(267)	$ 305	(408)	$ 249
Forward Loan Sale Commitments [Member] | Other Assets [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Assets, Fair Value	0		0		0
Forward Loan Sale Commitments [Member] | Other Liabilities [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 510		$ 510		$ 102