Commercial mortgage banking - Components of Mortgage Servicing Rights Fees (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Servicing fees	$ 1,208	$ 927
Late fees	62	23
Ancillary fees	57	97
Total MSR fees	$ 1,327	$ 1,047

All amounts that are due to the servicer of a financial asset, excluding contractually specified servicing fees and late fees.

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All amounts that, per contract, are due to the servicer in exchange for servicing the financial asset and would no longer be received by a servicer if the beneficial owners of the serviced assets (or their trustees or agents) were to exercise their actual or potential authority under the contract to shift the servicing to another servicer. Depending on the servicing contract, those fees may include some or all of the difference between the interest rate collected on the asset being serviced and the rate to be paid to the beneficial owners of the asset.

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- Definition

All amounts that are due to the servicer of a financial asset as a result of the debt holder not meeting the monthly payment terms.

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