Company's Interest Rate Swaps (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Pay Fixed Or Receive Variable Swaps
Derivative [Line Items]
Notional Amount	$ 17,949,000	$ 27,127,000
Estimate Fair Value	(1,280,000)	(1,529,000)
Years to Maturity	2 years 8 months 12 days	3 years
Receive Rate	2.44%	2.65%
Pay Rate	5.41%	4.66%
Pay Variable Or Receive Fixed Swaps
Derivative [Line Items]
Notional Amount	17,949,000	27,127,000
Estimate Fair Value	1,280,000	1,529,000
Years to Maturity	2 years 8 months 12 days	3 years
Receive Rate	5.41%	4.66%
Pay Rate	2.44%	2.65%
Swap
Derivative [Line Items]
Notional Amount	35,898,000	54,254,000
Estimate Fair Value	$ 0	$ 0
Years to Maturity	2 years 8 months 12 days	3 years
Receive Rate	3.92%	3.66%
Pay Rate	3.92%	3.66%