Remaining Maturities of Short Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Short-term Debt [Line Items]
Short-term debt	$ 838,299	$ 551,918
Within 30 Days
Short-term Debt [Line Items]
Short-term debt	345,333	362,279
31 to 90 Days
Short-term Debt [Line Items]
Short-term debt	206,281	48,848
Over 90 Days
Short-term Debt [Line Items]
Short-term debt	$ 286,685	$ 140,791