Derivatives and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2010 Interest Rate Swaps Derivative
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional value of two pay-fixed interest rate swaps			$ 55,800,000
Weighted average interest rate			1.41%
Number of derivative instruments			2
Additional reclassification from other comprehensive income as an increase to interest expense	459,000
Amounts recorded as earnings attributable to hedge ineffectiveness	0	0
Fair value of derivatives in net liability position	$ 515,000