Derivatives and Hedging Activities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012 Derivative	Dec. 31, 2011
Derivative [Line Items]
Termination value of derivatives in net liability position	$ 3,600,000
Derivatives not Designated as Hedging Instruments | Interest Rate Swap
Derivative [Line Items]
Number of interest rate swaps	20
Notional amount of interest rate swaps	196,100,000
Amount of Loss Recognized	$ 79,000	$ 13,000