Other assets by major categories (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Net deferred tax assets (net of valuation allowance)	$ 864,284	$ 541,499
Investments under the equity method	265,524	246,776
Bank Owned Life Insurance	227,213	233,475
Prepaid F D I C Insurance Assessment	396	27,533
Prepaid Taxes	107,253	88,360
Other prepaid expenses	60,852	60,626
Derivative Asset, Fair Value, Gross Asset	37,697	41,925
Trades receivables from brokers and counterparties	158,141	137,542	87,774
Others	214,066	191,842
Total other assets	$ 1,935,426	$ 1,569,578