Fair Value - Quantitative Information about Significant Unobservable Inputs Used in Fair Value Measurements (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	13.00%	13.00%
Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 3,427	$ 6,771
Valuation Techniques	Fair value of collateral	Fair value of collateral
Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 28,997	$ 11,632
Valuation Techniques	Fair value of collateral	Fair value of collateral
Minimum [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.00%	0.00%
Minimum [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	10.00%	10.00%
Maximum [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	74.00%	99.00%
Maximum [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	67.00%	67.00%
Weighted Average [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	38.00%	53.00%
Weighted Average [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	32.00%	36.00%
Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 8,097	$ 8,119
Valuation Techniques	Discounted cash flow	Discounted cash flow
Pooled Trust Preferred Securities [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	3.10%	4.50%
Expected asset recoveries	0.00%	0.00%
Pooled Trust Preferred Securities [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	4.40%	10.00%
Expected asset recoveries	4.10%	6.10%
Pooled Trust Preferred Securities [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	4.10%	7.90%
Expected asset recoveries	0.60%	0.90%
Commercial Real Estate Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 2,452	$ 1,352
Valuation Techniques	Fair value of collateral	Fair value of collateral
Commercial Real Estate Foreclosed Assets [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	16.00%	4.00%
Commercial Real Estate Foreclosed Assets [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	55.00%	80.00%
Commercial Real Estate Foreclosed Assets [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	26.00%	39.00%
Residential Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		$ 394
Valuation Techniques		Fair value of collateral
Residential Foreclosed Assets [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		7.00%
Residential Foreclosed Assets [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		60.00%
Residential Foreclosed Assets [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		30.00%