Derivative Instruments and Hedging Activities - 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, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amounts Related To Interest Rate Derivatives Included In Income Designated As Hedges Of Cash Flows [Line Items]
Amount of loss reclassified from accumulated other comprehensive loss to interest on short-term borrowings	$ (42,483)	$ (44,787)	$ (85,480)	$ (91,464)
Amount of loss recognized in other comprehensive income	3,508	(5,288)	3,375	(3,739)
Reclassification out of accumulated other comprehensive income (loss) [Member]
Amounts Related To Interest Rate Derivatives Included In Income Designated As Hedges Of Cash Flows [Line Items]
Amount of loss reclassified from accumulated other comprehensive loss to interest on short-term borrowings	$ (1,714)	$ (1,398)	$ (3,594)	$ (2,790)