Recent Market Developments - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013
Recent Market Development [Line Items]
FDIC deposit insurance amount	$ 250,000
Uniform increase in assessment rates effective on January 1, 2011	0.03%
Company is carrying a prepaid asset		2,400,000
Company received refund	$ 2,400,000
Common equity Tier 1 ratio as percentage of risk-weighted assets	4.50%
Minimum Tier 1 capital ratio as percentage of risk-weighted assets	4.00%
Revised minimum Tier 1 capital ratio as percentage of risk-weighted assets	6.00%
Tier 1 capital conservation buffer as percentage of risk-weighted assets	2.50%
Minimum [Member]
Recent Market Development [Line Items]
Restoration period	7 years
Maximum [Member]
Recent Market Development [Line Items]
Restoration period	8 years