Loans and Leases (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 4,641.3
2019	4,382.1
2018	1,578.5
2017	1,403.0
2016	1,583.1
PRIOR	3,662.3
REVOLVING LOANS	16,091.7
REVOLVING LOANS CONVERTED TO TERM LOANS	415.3
Total Loans and Leases	33,757.3	$ 31,409.6
Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	16.5
2019	50.3
2018	13.9
2017	0.5
2016	0.5
PRIOR	10.7
REVOLVING LOANS	272.4
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	369.9
Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9.3
2019	22.1
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.9
REVOLVING LOANS	61.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	93.8
Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	7.2
2019	28.2
2018	13.9
2017	0.5
2016	0.5
PRIOR	9.6
REVOLVING LOANS	210.9
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	275.9
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	0.2
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	0.2
COMMERCIAL
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,586.2
2019	2,480.0
2018	1,093.1
2017	932.1
2016	891.6
PRIOR	1,408.9
REVOLVING LOANS	6,291.0
REVOLVING LOANS CONVERTED TO TERM LOANS	86.9
Total Loans and Leases	15,769.8	14,001.3
COMMERCIAL | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2020	682.4
2019	1,397.9
2018	681.1
2017	720.3
2016	653.6
PRIOR	692.9
REVOLVING LOANS	5,862.1
REVOLVING LOANS CONVERTED TO TERM LOANS	55.5
Total Loans and Leases	10,745.8	9,091.1
COMMERCIAL | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	288.0
2019	595.8
2018	252.4
2017	209.8
2016	517.6
PRIOR	473.4
REVOLVING LOANS	4,219.5
REVOLVING LOANS CONVERTED TO TERM LOANS	2.1
Total Loans and Leases	6,558.6
COMMERCIAL | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	366.6
2019	674.9
2018	383.1
2017	494.9
2016	96.7
PRIOR	199.0
REVOLVING LOANS	1,376.7
REVOLVING LOANS CONVERTED TO TERM LOANS	51.2
Total Loans and Leases	3,643.1
COMMERCIAL | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	27.8
2019	127.2
2018	45.6
2017	15.6
2016	39.3
PRIOR	20.5
REVOLVING LOANS	265.9
REVOLVING LOANS CONVERTED TO TERM LOANS	2.2
Total Loans and Leases	544.1
COMMERCIAL | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	589.3
2019	1,034.9
2018	400.2
2017	199.6
2016	238.0
PRIOR	585.5
REVOLVING LOANS	185.6
REVOLVING LOANS CONVERTED TO TERM LOANS	29.6
Total Loans and Leases	3,262.7	3,104.3
COMMERCIAL | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	235.7
2019	199.9
2018	65.7
2017	52.8
2016	70.5
PRIOR	157.3
REVOLVING LOANS	128.7
REVOLVING LOANS CONVERTED TO TERM LOANS	8.7
Total Loans and Leases	919.3
COMMERCIAL | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	352.3
2019	820.2
2018	330.8
2017	113.1
2016	160.4
PRIOR	396.5
REVOLVING LOANS	56.9
REVOLVING LOANS CONVERTED TO TERM LOANS	20.9
Total Loans and Leases	2,251.1
COMMERCIAL | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1.3
2019	14.8
2018	3.7
2017	33.7
2016	7.1
PRIOR	31.7
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	92.3
COMMERCIAL | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	929.4
2019	47.2
2018	11.8
2017	12.2
2016	0.0
PRIOR	79.1
REVOLVING LOANS	243.3
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	1,324.8	1,576.3
COMMERCIAL | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	825.1
2019	21.4
2018	10.0
2017	12.2
2016	0.0
PRIOR	13.5
REVOLVING LOANS	34.2
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	916.4
COMMERCIAL | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	103.1
2019	2.7
2018	1.8
2017	0.0
2016	0.0
PRIOR	65.6
REVOLVING LOANS	37.9
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	212.9
COMMERCIAL | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1.2
2019	23.1
2018	0.0
2017	0.0
2016	0.0
PRIOR	0.0
REVOLVING LOANS	171.2
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	195.5
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	51.4
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	51.4	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	39.5
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	39.5
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	11.9
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
Total Loans and Leases	11.9
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	385.1
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	385.1	164.0
COMMERCIAL | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	123.7
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	123.7
COMMERCIAL | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	261.4
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	261.4
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	2,055.1
2019	1,902.1
2018	485.4
2017	470.9
2016	691.5
PRIOR	2,253.4
REVOLVING LOANS	9,800.7
REVOLVING LOANS CONVERTED TO TERM LOANS	328.4
Total Loans and Leases	17,987.5	17,408.3
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2020	607.8
2019	977.2
2018	222.2
2017	135.5
2016	120.2
PRIOR	247.1
REVOLVING LOANS	8,993.3
REVOLVING LOANS CONVERTED TO TERM LOANS	318.0
Total Loans and Leases	11,621.3	11,071.4
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	275.3
2019	442.7
2018	43.9
2017	67.4
2016	27.3
PRIOR	143.7
REVOLVING LOANS	4,551.9
REVOLVING LOANS CONVERTED TO TERM LOANS	24.9
Total Loans and Leases	5,577.1
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	332.0
2019	527.1
2018	155.5
2017	64.9
2016	92.8
PRIOR	103.4
REVOLVING LOANS	4,377.0
REVOLVING LOANS CONVERTED TO TERM LOANS	284.8
Total Loans and Leases	5,937.5
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.5
2019	7.4
2018	22.8
2017	3.2
2016	0.1
PRIOR	0.0
REVOLVING LOANS	64.4
REVOLVING LOANS CONVERTED TO TERM LOANS	8.3
Total Loans and Leases	106.7
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,377.0
2019	874.6
2018	249.3
2017	334.9
2016	570.8
PRIOR	1,995.6
REVOLVING LOANS	535.0
REVOLVING LOANS CONVERTED TO TERM LOANS	5.3
Total Loans and Leases	5,942.5	6,095.0
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	903.6
2019	504.5
2018	91.6
2017	119.4
2016	244.2
PRIOR	798.2
REVOLVING LOANS	201.6
REVOLVING LOANS CONVERTED TO TERM LOANS	1.3
Total Loans and Leases	2,864.4
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	460.3
2019	359.1
2018	156.8
2017	214.1
2016	323.7
PRIOR	1,088.1
REVOLVING LOANS	300.2
REVOLVING LOANS CONVERTED TO TERM LOANS	4.0
Total Loans and Leases	2,906.3
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	13.1
2019	11.0
2018	0.9
2017	1.4
2016	2.9
PRIOR	109.3
REVOLVING LOANS	33.2
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]
Total Loans and Leases	369.9	174.8
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	53.8
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	53.8	$ 67.1
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	37.4
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	37.4
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	16.4
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	16.4
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