Effect of Derivative Financial Instruments on Consolidated Statements of Income and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative [Line Items]
Amount of loss recognized in OCI on derivative (effective portion)	$ 106	$ 494	$ 141	$ 1,765
Derivatives in Cash Flow Hedging Relationships | Interest Expense [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount of loss reclassified from accumulated OCI into income (effective portion)	$ 467	$ 440	$ 1,374	$ 1,299