The Conversion - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended		12 Months Ended
	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Jun. 30, 2012	Jul. 07, 2011	Mar. 08, 2011
Conversion of Stock [Line Items]
Common stock, par value		$ 0.01			$ 0.01		$ 0.01
Common stock share issued		4,634,703			4,811,255		4,811,255
Number of common stock shares subscriptions						4,496,500
Conversion of common stock per share						$ 10
Proceeds from subscribed convertible common stock		$ 44,965,000
Percentage of subscribed share donated							7.00%
Shares donated to the charitable foundation							314,755
Cash contributed to the foundation	450,000		450,000
Number of donated shares	314,755	314,755
Donated shares valued	3,147,550		3,147,550
Donation shares of common stock per share value	$ 10.00
Subscription offering resulted in the receipt				113,000,000
Reflected deposits held in escrow				113,000,000
Approximate amount refunded to subscribers	68,900,000
Percentage of shares purchased under employee stock ownership plan		8.00%
Shares purchase at employee stock ownership plan, shares		384,900	384,900
Shares purchase at employee stock ownership plan, value		3,849,000
Association incurred conversion costs				766,209
Conversion costs		$ 1,730,000