Location In Financial Statements of Gain Or Loss Recognized on Interest Rate Derivatives Designated as Cash Flow Hedges (Detail) (Interest Rate Swap, USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in accumulated other comprehensive income on interest rate derivatives (effective portion)	$ (291)	$ (587)
Amount of gain (loss) reclassified from accumulated other comprehensive income into income as interest expense (effective portion)	(50)	(66)
Amount of gain (loss) recognized in income on derivative instruments (ineffective portion and amounts excluded from effectiveness testing)	$ (1)	$ (2)