Derivative Financial Instruments - Effect of Derivative Financial Instruments on Income Statement (Detail) (Not Designated as Hedging Instrument, Interest Rate Contract, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Other Income
Derivative [Line Items]
Amount of Gain (Loss) Recognized Income on Derivative	$ (79)	$ (94)
Cash Flow Hedging
Derivative [Line Items]
Amount of Loss Recognized in Other Comprehensive Income on Derivative (Effective Portion)	(1,466)	(3,274)
Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Amount of Loss Reclassified from Other Comprehensive Income Into Income (Effective Portion)	$ (217)