Loans and Leases (Credit Quality Indicator At Amortized Cost Basis By Origination Year) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 4,932.9
2019	4,878.5
2018	1,900.1
2017	1,682.8
2016	1,746.3
PRIOR	4,224.0
REVOLVING LOANS	18,101.9
REVOLVING LOANS CONVERTED TO TERM LOANS	371.2
Total Loans and Leases	37,837.7	$ 31,409.6
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,333.9
2019	2,544.8
2018	1,176.2
2017	978.0
2016	944.1
PRIOR	1,493.7
REVOLVING LOANS	8,179.7
REVOLVING LOANS CONVERTED TO TERM LOANS	86.4
Total Loans and Leases	19,736.8	14,001.3
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2020	312.6
2019	1,467.9
2018	719.9
2017	745.8
2016	672.6
PRIOR	719.1
REVOLVING LOANS	7,631.0
REVOLVING LOANS CONVERTED TO TERM LOANS	58.4
Total Loans and Leases	12,327.3	9,091.1
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	151.0
2019	787.4
2018	340.4
2017	287.4
2016	533.0
PRIOR	509.2
REVOLVING LOANS	5,880.6
REVOLVING LOANS CONVERTED TO TERM LOANS	4.9
Total Loans and Leases	8,493.9
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	137.7
2019	668.7
2018	370.5
2017	449.0
2016	120.2
PRIOR	203.8
REVOLVING LOANS	1,676.4
REVOLVING LOANS CONVERTED TO TERM LOANS	51.1
Total Loans and Leases	3,677.4
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	23.9
2019	11.8
2018	9.0
2017	9.4
2016	19.4
PRIOR	6.1
REVOLVING LOANS	74.0
REVOLVING LOANS CONVERTED TO TERM LOANS	2.4
Total Loans and Leases	156.0
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	289.5
2019	1,035.7
2018	444.4
2017	219.9
2016	271.5
PRIOR	625.4
REVOLVING LOANS	172.6
REVOLVING LOANS CONVERTED TO TERM LOANS	26.2
Total Loans and Leases	3,085.2	3,104.3
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	121.0
2019	285.9
2018	100.5
2017	61.2
2016	100.5
PRIOR	170.7
REVOLVING LOANS	106.6
REVOLVING LOANS CONVERTED TO TERM LOANS	6.1
Total Loans and Leases	952.5
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	166.3
2019	749.8
2018	343.9
2017	154.3
2016	168.0
PRIOR	454.2
REVOLVING LOANS	66.0
REVOLVING LOANS CONVERTED TO TERM LOANS	20.1
Total Loans and Leases	2,122.6
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2.2
2019	0.0
2018	0.0
2017	4.4
2016	3.0
PRIOR	0.5
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	10.1
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,395.3
2019	41.2
2018	11.9
2017	12.3
2016	0.0
PRIOR	84.4
REVOLVING LOANS	376.1
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	3,923.0	1,576.3
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,488.3
2019	12.2
2018	10.0
2017	5.6
2016	0.0
PRIOR	13.5
REVOLVING LOANS	169.1
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	2,698.7
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	905.6
2019	5.9
2018	1.9
2017	6.7
2016	0.0
PRIOR	70.9
REVOLVING LOANS	38.6
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	1,031.4
Commercial | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1.4
2019	23.1
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	168.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	192.9
Commercial | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	64.8
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	64.8	65.6
Commercial | Lease Financing, net | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	52.8
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	52.8
Commercial | Lease Financing, net | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	12.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	12.0
Commercial | Lease Financing, net | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	0.0
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	336.5
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	336.5	164.0
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	117.4
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	117.4
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	219.1
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	219.1
Commercial | Other | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	0.0
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2020	599.0
2019	2,333.7
2018	723.9
2017	704.8
2016	802.2
PRIOR	2,730.3
REVOLVING LOANS	9,922.2
REVOLVING LOANS CONVERTED TO TERM LOANS	284.8
Total Loans and Leases	18,100.9	17,408.3
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2020	181.5
2019	1,018.4
2018	357.9
2017	298.4
2016	136.5
PRIOR	253.9
REVOLVING LOANS	9,088.9
REVOLVING LOANS CONVERTED TO TERM LOANS	274.4
Total Loans and Leases	11,609.9	11,071.4
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	131.1
2019	486.6
2018	75.1
2017	126.9
2016	38.9
PRIOR	150.2
REVOLVING LOANS	4,965.0
REVOLVING LOANS CONVERTED TO TERM LOANS	20.9
Total Loans and Leases	5,994.7
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	50.4
2019	531.2
2018	259.6
2017	171.5
2016	97.5
PRIOR	103.7
REVOLVING LOANS	4,076.9
REVOLVING LOANS CONVERTED TO TERM LOANS	243.2
Total Loans and Leases	5,534.0
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.6
2018	23.2
2017	0.0
2016	0.1
PRIOR	0.0
REVOLVING LOANS	47.0
REVOLVING LOANS CONVERTED TO TERM LOANS	10.3
Total Loans and Leases	81.2
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	345.5
2019	1,254.7
2018	352.0
2017	405.8
2016	665.2
PRIOR	2,464.2
REVOLVING LOANS	581.6
REVOLVING LOANS CONVERTED TO TERM LOANS	5.3
Total Loans and Leases	6,074.3	6,095.0
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	222.8
2019	801.7
2018	112.6
2017	156.3
2016	244.7
PRIOR	942.8
REVOLVING LOANS	228.8
REVOLVING LOANS CONVERTED TO TERM LOANS	1.3
Total Loans and Leases	2,711.0
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	122.4
2019	441.7
2018	229.0
2017	248.9
2016	417.5
PRIOR	1,397.2
REVOLVING LOANS	330.8
REVOLVING LOANS CONVERTED TO TERM LOANS	4.0
Total Loans and Leases	3,191.5
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.3
2019	11.3
2018	10.4
2017	0.6
2016	3.0
PRIOR	124.2
REVOLVING LOANS	22.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	171.8
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2.2
2019	60.6
2018	14.0
2017	0.6
2016	0.5
PRIOR	12.2
REVOLVING LOANS	251.7
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	346.9	174.8
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2.2
2019	41.5
2018	0.0
2017	0.0
2016	0.0
PRIOR	2.0
REVOLVING LOANS	58.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	104.1
Personal | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	19.1
2018	14.0
2017	0.6
2016	0.5
PRIOR	9.6
REVOLVING LOANS	193.0
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	241.9
Personal | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.6
REVOLVING LOANS	0.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	0.9
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	69.8
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	69.8	$ 67.1
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	36.5
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	36.5
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33.3
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	33.3
Personal | Other | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.0
2019	0.0
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	$ 0.0