Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule Of Income Taxes [Line Items]
Deferred tax valuation allowance	$ 474	$ 474	$ 474
Bancshares Inc [Member]
Schedule Of Income Taxes [Line Items]
Net operating losses carryforwards	$ 15,700
Bancshares Inc [Member] | Minimum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2030
Bancshares Inc [Member] | Maximum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2034
Intervest Bancshares Corporation [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards subject to expiration	$ 6,300
Intervest Bancshares Corporation [Member] | Minimum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2030
Intervest Bancshares Corporation [Member] | Maximum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2035
FNB Shelby [Member]
Schedule Of Income Taxes [Line Items]
Net operating losses carryforwards	$ 20,000
FNB Shelby [Member] | Expiration Year 2032 [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2032
Operating loss carryforwards subject to expiration	$ 12,500
FNB Shelby [Member] | Expiration Year 2033 [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carryforwards expiration year	2033
Operating loss carryforwards subject to expiration	$ 7,500