Derivative Financial Instruments - Schedule of Notional Amount and Fair Value Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Asset derivatives, notional amount	$ 291,809	$ 251,721
Asset derivatives designated as hedging instruments	3,329	538
Liability derivatives, notional amount	343,000	255,295
Asset derivatives not designated as hedging instruments	6,653	4,561
Total asset derivatives	9,982	5,099
Liability derivatives designated as hedging instruments	0	165
Liability derivatives not designated as hedging instruments	1,422	312
Total liability derivatives	1,422	477
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset derivatives, notional amount	87,672	71,831
Liability derivatives, notional amount	0	18,795
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset derivatives, notional amount	204,137	179,890
Liability derivatives, notional amount	343,000	236,500
Other Assets [Member] | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Asset derivatives not designated as hedging instruments	6,541	4,559
Other Assets [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Asset derivatives, notional amount	182,030	148,866
Other Liabilities [Member] | TBA Mortgage Backed Securities [Member]
Derivative [Line Items]
Liability derivatives not designated as hedging instruments	1,422	312
Other Liabilities [Member] | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Liability derivatives not designated as hedging instruments	0	0
Other Liabilities [Member] | Not Designated as Hedging Instrument [Member] | TBA Mortgage Backed Securities [Member]
Derivative [Line Items]
Liability derivatives, notional amount	343,000	236,500
Other Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Liability derivatives, notional amount	0	0
Interest Rate Swap Contracts [Member] | Other Assets [Member] | Fair Value Hedging [Member] | Hedged Commercial Loans [Member]
Derivative [Line Items]
Asset derivatives designated as hedging instruments	3,329	538
Interest Rate Swap Contracts [Member] | Other Assets [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Hedged Commercial Loans [Member]
Derivative [Line Items]
Asset derivatives, notional amount	87,672	71,831
Interest Rate Swap Contracts [Member] | Other Liabilities [Member] | Fair Value Hedging [Member] | Hedged Commercial Loans [Member]
Derivative [Line Items]
Liability derivatives designated as hedging instruments	0	165
Interest Rate Swap Contracts [Member] | Other Liabilities [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Hedged Commercial Loans [Member]
Derivative [Line Items]
Liability derivatives, notional amount	0	18,795
Forward Loan Sale Commitments [Member] | Other Assets [Member]
Derivative [Line Items]
Asset derivatives not designated as hedging instruments	112	2
Forward Loan Sale Commitments [Member] | Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset derivatives, notional amount	$ 22,107	$ 31,024