Recent Market Developments - Additional Information (Detail) (USD $)	0 Months Ended	9 Months Ended
	Nov. 02, 2009	Sep. 30, 2013	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%
Amount of prepaid asset carried by company				2,400,000
Refund amount received by company			$ 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