Derivative Financial Instruments - Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Total Asset Derivatives	$ 3,836	$ 954
Total Liability Derivatives	4,552	2,542
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total Asset Derivatives	3,579	811
Total Liability Derivatives	4,548	2,539
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts One [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Liability Derivatives	3,579	811
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts Two [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Liability Derivatives	969	1,728
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts Two [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total Asset Derivatives	3,579	811
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total Asset Derivatives	257	143
Total Liability Derivatives	4	3
Derivatives Not Designated as Hedging Instruments [Member] | Mortgage Loan Contracts [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Liability Derivatives	4	3
Derivatives Not Designated as Hedging Instruments [Member] | Mortgage Loan Contracts [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total Asset Derivatives	$ 257	$ 143