Gains (Losses) Related to Interest Rate Derivatives Designated as Hedges of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Amount of loss reclassified from accumulated other comprehensive income (loss) to interest on short-term borrowings	$ (1,398)	$ (611)	$ (2,790)	$ (1,188)
Amount of loss recognized in other comprehensive income (loss)	$ (5,288)	$ (6,533)	$ (3,739)	$ (5,099)