Loan and Lease Segment and Class Balances Segregated by Borrower Ratings into "One to Three", "Four to Five" and "Six to Nine" (Watch List) Categories (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Commercial Real Estate	$ 3,848.8	$ 3,333.3
Lease Financing, net	544.4	916.3
Residential Real Estate	8,900.0	9,800.0
Total Loans and Leases	33,180.9	31,640.2
1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	17,910.4	16,322.9
4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	14,688.3	14,680.4
6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	582.2	636.9
Commercial
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	9,431.5	8,381.9
Commercial Real Estate	3,848.8	3,333.3
Lease Financing, net	544.4	916.3
Non-U.S.	1,137.7	1,530.6
Other	194.1	191.5
Total Loans and Leases	15,156.5	14,353.6
Commercial \| 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	6,360.6	5,340.9
Commercial Real Estate	1,822.6	1,371.7
Lease Financing, net	377.0	552.5
Non-U.S.	313.8	636.8
Other	94.9	108.1
Total Loans and Leases	8,968.9	8,010.0
Commercial \| 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	2,897.2	2,947.3
Commercial Real Estate	1,992.7	1,861.8
Lease Financing, net	133.1	360.3
Non-U.S.	823.3	892.9
Other	99.2	83.4
Total Loans and Leases	5,945.5	6,145.7
Commercial \| 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	173.7	93.7
Commercial Real Estate	33.5	99.8
Lease Financing, net	34.3	3.5
Non-U.S.	0.6	0.9
Total Loans and Leases	242.1	197.9
Personal
Financing Receivable, Recorded Investment [Line Items]
Other	37.3	37.1
Residential Real Estate	8,850.7	9,782.6
Private Client	9,136.4	7,466.9
Total Loans and Leases	18,024.4	17,286.6
Personal \| 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Other	18.3	21.1
Residential Real Estate	3,014.9	3,148.0
Private Client	5,908.3	5,143.8
Total Loans and Leases	8,941.5	8,312.9
Personal \| 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Other	19.0	16.0
Residential Real Estate	5,516.7	6,207.0
Private Client	3,207.1	2,311.7
Total Loans and Leases	8,742.8	8,534.7
Personal \| 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Residential Real Estate	319.1	427.6
Private Client	21.0	11.4
Total Loans and Leases	$ 340.1	$ 439.0

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Loans and Leases Receivable, Residential, Real Estate

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Amount before allowance of commercial leases and leveraged lease transactions where the entity is long-term creditor. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes leases covered under loss sharing agreements.

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Reflects the net carrying amount of foreign loans and leases held in portfolio, after deducting deferred income, but before deducting the allowance for losses on foreign loans and leases.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of other loans and leases not otherwise specified in the taxonomy. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of loans issued to agricultural, commercial and industrial, and financial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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