Allowance for Credit Losses (Detail) (USD $)	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of the period	$ 44,661,000	$ 40,200,000
Recoveries	(27,539,000)	(20,991,000)
Provisions	10,066,000	22,084,000
Balance, end of the period	$ 27,188,000	$ 41,293,000