Other assets by major categories (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Net deferred tax assets (net of valuation allowance)	$ 844,242	$ 541,499
Investments under the equity method	213,614	246,776
Bank Owned Life Insurance	227,916	233,475
Prepaid F D I C Insurance Assessment	0	27,533
Prepaid Taxes	98,972	88,360
Other prepaid expenses	65,319	60,626
Derivative Asset, Fair Value, Gross Asset	32,732	41,925
Trades receivables from brokers and counterparties	85,746	137,542	287,322
Others	234,937	191,842
Total other assets	$ 1,803,478	$ 1,569,578