Commitments and Contingencies - Gains (Losses) Related to Interest Rate Derivatives Designated as Hedges of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amount of loss reclassified from accumulated other comprehensive income or loss to interest on short-term borrowings	$ (6,478)	$ (3,067)	$ (1,967)
Amount of (loss) gain recognized in other comprehensive income (loss)	$ (5,774)	$ (24,393)	$ 1,494