Loans and leases - Summary of Lease Financing Receivables (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Direct financings:
Lease payments receivable	$ 1,106,434	$ 1,137,310
Estimated residual value of leased assets	96,468	96,479
unearned income	(134,428)	(153,704)
Investment in direct financings	1,068,474	1,080,085
Leveraged leases:
Lease payments receivable	132,466	154,551
Estimated residual value of leased assets	137,570	144,275
Unearned income	(50,378)	(53,847)
Investment in leveraged leases	219,658	244,979
Total investment in leases.	1,288,132	1,325,064
Deferred taxes payable arising from leveraged leases	$ 172,026	$ 180,731

Net investment in direct financing and leveraged type leases.

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The net investment in direct financing leases as of the balance sheet date consisting of: (a) minimum lease payments due on direct financing leases, (b) unguaranteed residual value, and (c) any unamortized initial direct costs; less: (i) executory costs, (ii) unearned income, and (iii) the accumulated allowance for uncollectible minimum lease payments.

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The remaining (unamortized) difference between the gross investment in a direct financing lease and the cost or carrying amount, if different, of the leased property as of the balance sheet date.

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Amount of remaining payments as of the balance sheet date that lessees are obligated to make or can be required to make under direct financing leases, including any guarantee of residual value and executory costs. The amount also includes any guaranteed rental payments by an unrelated third-party provided that are financially capable of making such payments.

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The estimate of the lease property's economic value at the end of the direct financing lease term excluding any amounts guaranteed by either the lessee or a third-party.

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The estimated portion of pretax income and investment tax credit remaining to be allocated to income over the lease term.

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Taxes arising from arrangements meeting the criteria for classification as leveraged leases due to timing differences between accounting and tax income recognition.

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The net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.

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This element represents leveraged lease rentals receivable, net of that portion of the rental applicable to principal and interest on the nonrecourse debt.

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The estimate of the value of the leased asset at the end of the lease term.

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