Loans and Leases (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	$ 7,255.8	$ 7,448.6
2020/2019	5,025.1	3,667.9
2019/2018	2,888.9	1,352.6
2018/2017	1,053.2	1,123.1
2017/2016	738.8	1,254.8
PRIOR	2,843.4	3,128.5
REVOLVING LOANS	19,346.7	15,453.6
REVOLVING LOANS CONVERTED TO TERM LOANS	304.7	330.6
TOTAL LOANS AND LEASES	39,456.6	33,759.7
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	4,997.8	3,772.7
2020/2019	2,146.0	2,187.7
2019/2018	1,713.4	990.3
2018/2017	804.4	725.0
2017/2016	465.3	749.9
PRIOR	1,453.0	1,285.8
REVOLVING LOANS	6,806.9	5,490.9
REVOLVING LOANS CONVERTED TO TERM LOANS	59.1	59.7
TOTAL LOANS AND LEASES	18,445.9	15,262.0
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,822.7	1,491.5
2020/2019	933.3	1,170.9
2019/2018	766.3	596.0
2018/2017	483.4	544.2
2017/2016	329.7	553.6
PRIOR	864.3	622.1
REVOLVING LOANS	5,994.7	5,042.2
REVOLVING LOANS CONVERTED TO TERM LOANS	34.0	37.8
TOTAL LOANS AND LEASES	11,228.4	10,058.3
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	878.7	663.8
2020/2019	517.7	546.0
2019/2018	337.1	204.6
2018/2017	208.1	96.0
2017/2016	69.8	396.0
PRIOR	613.2	448.8
REVOLVING LOANS	4,565.5	3,742.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.1	5.5
TOTAL LOANS AND LEASES	7,190.2	6,103.1
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	918.7	793.4
2020/2019	388.6	505.1
2019/2018	380.8	354.1
2018/2017	244.4	405.4
2017/2016	249.9	134.6
PRIOR	248.4	167.3
REVOLVING LOANS	1,345.5	1,238.7
REVOLVING LOANS CONVERTED TO TERM LOANS	33.9	32.3
TOTAL LOANS AND LEASES	3,810.2	3,630.9
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	25.3	34.3
2020/2019	27.0	119.8
2019/2018	48.4	37.3
2018/2017	30.9	42.8
2017/2016	10.0	23.0
PRIOR	2.7	6.0
REVOLVING LOANS	83.7	61.1
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	228.0	324.3
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,238.9	1,124.7
2020/2019	981.7	976.2
2019/2018	907.4	392.3
2018/2017	319.0	169.7
2017/2016	126.5	196.3
PRIOR	506.4	494.4
REVOLVING LOANS	230.6	184.7
REVOLVING LOANS CONVERTED TO TERM LOANS	23.3	20.1
TOTAL LOANS AND LEASES	4,333.8	3,558.4
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	390.0	406.3
2020/2019	241.5	109.2
2019/2018	250.7	27.6
2018/2017	91.0	36.5
2017/2016	15.5	11.8
PRIOR	79.6	99.4
REVOLVING LOANS	156.2	124.3
REVOLVING LOANS CONVERTED TO TERM LOANS	2.7	8.7
TOTAL LOANS AND LEASES	1,227.2	823.8
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	829.4	703.1
2020/2019	740.2	811.8
2019/2018	601.4	332.7
2018/2017	228.0	107.4
2017/2016	90.7	184.5
PRIOR	415.8	382.8
REVOLVING LOANS	74.4	60.4
REVOLVING LOANS CONVERTED TO TERM LOANS	20.6	11.4
TOTAL LOANS AND LEASES	3,000.5	2,594.1
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	19.5	15.3
2020/2019	0.0	55.2
2019/2018	55.3	32.0
2018/2017	0.0	25.8
2017/2016	20.3	0.0
PRIOR	11.0	12.2
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	106.1	140.5
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,586.4	868.3
2020/2019	231.0	40.6
2019/2018	39.7	2.0
2018/2017	2.0	11.1
2017/2016	9.1	0.0
PRIOR	71.3	157.9
REVOLVING LOANS	581.6	264.0
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8	1.8
TOTAL LOANS AND LEASES	2,522.9	1,345.7
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,325.4	555.2
2020/2019	231.0	16.8
2019/2018	16.6	0.0
2018/2017	0.0	11.1
2017/2016	9.1	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	491.2	78.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	2,073.3	661.6
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	260.9	313.1
2020/2019	0.0	0.7
2019/2018	0.0	2.0
2018/2017	2.0	0.0
2017/2016	0.0	0.0
PRIOR	71.3	157.9
REVOLVING LOANS	81.4	39.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8	1.8
TOTAL LOANS AND LEASES	417.4	514.7
Commercial | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.1	0.0
2020/2019	0.0	23.1
2019/2018	23.1	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	9.0	146.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	32.2	169.4
Commercial | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.0	0.0
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	11.0	11.4
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	11.0	11.4
Commercial | Lease Financing, net | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.0	0.0
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	11.0	11.4
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	11.0	11.4
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	349.8	288.2
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	349.8	288.2
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	154.5	81.7
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	154.5	81.7
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	195.3	206.5
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	195.3	206.5
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	2,258.0	3,675.9
2020/2019	2,879.1	1,480.2
2019/2018	1,175.5	362.3
2018/2017	248.8	398.1
2017/2016	273.5	504.9
PRIOR	1,390.4	1,842.7
REVOLVING LOANS	12,539.8	9,962.7
REVOLVING LOANS CONVERTED TO TERM LOANS	245.6	270.9
TOTAL LOANS AND LEASES	21,010.7	18,497.7
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	718.8	1,166.7
2020/2019	726.5	754.1
2019/2018	620.8	191.1
2018/2017	123.2	124.0
2017/2016	96.3	87.7
PRIOR	204.3	213.6
REVOLVING LOANS	11,893.3	9,021.2
REVOLVING LOANS CONVERTED TO TERM LOANS	230.6	256.7
TOTAL LOANS AND LEASES	14,613.8	11,815.1
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	282.7	668.6
2020/2019	227.6	273.7
2019/2018	86.9	51.7
2018/2017	13.4	60.4
2017/2016	53.9	10.2
PRIOR	131.4	136.1
REVOLVING LOANS	7,399.7	5,392.8
REVOLVING LOANS CONVERTED TO TERM LOANS	64.3	47.9
TOTAL LOANS AND LEASES	8,259.9	6,641.4
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	435.1	492.1
2020/2019	493.5	479.9
2019/2018	533.9	117.3
2018/2017	89.0	60.4
2017/2016	42.4	77.5
PRIOR	72.7	77.5
REVOLVING LOANS	4,490.9	3,564.7
REVOLVING LOANS CONVERTED TO TERM LOANS	166.3	207.3
TOTAL LOANS AND LEASES	6,323.8	5,076.7
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1.0	6.0
2020/2019	5.4	0.5
2019/2018	0.0	22.1
2018/2017	20.8	3.2
2017/2016	0.0	0.0
PRIOR	0.2	0.0
REVOLVING LOANS	2.7	63.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	1.5
TOTAL LOANS AND LEASES	30.1	97.0
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,322.6	2,424.2
2020/2019	2,145.5	685.2
2019/2018	517.6	159.4
2018/2017	115.2	273.6
2017/2016	177.2	416.7
PRIOR	1,180.9	1,619.1
REVOLVING LOANS	395.9	448.4
REVOLVING LOANS CONVERTED TO TERM LOANS	2.1	9.1
TOTAL LOANS AND LEASES	5,857.0	6,035.7
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	923.7	1,554.3
2020/2019	1,142.4	317.4
2019/2018	231.5	42.9
2018/2017	24.1	109.9
2017/2016	67.1	205.1
PRIOR	616.8	627.8
REVOLVING LOANS	143.1	152.8
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	1.7
TOTAL LOANS AND LEASES	3,148.7	3,011.9
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	398.4	854.6
2020/2019	993.3	359.5
2019/2018	278.2	115.8
2018/2017	90.5	163.2
2017/2016	109.6	209.7
PRIOR	494.8	896.5
REVOLVING LOANS	237.7	273.1
REVOLVING LOANS CONVERTED TO TERM LOANS	1.9	7.4
TOTAL LOANS AND LEASES	2,604.4	2,879.8
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.5	15.3
2020/2019	9.8	8.3
2019/2018	7.9	0.7
2018/2017	0.6	0.5
2017/2016	0.5	1.9
PRIOR	69.3	94.8
REVOLVING LOANS	15.1	22.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.2	0.0
TOTAL LOANS AND LEASES	103.9	144.0
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	48.2	36.0
2020/2019	7.1	40.9
2019/2018	37.1	11.8
2018/2017	10.4	0.5
2017/2016	0.0	0.5
PRIOR	5.2	10.0
REVOLVING LOANS	250.6	493.1
REVOLVING LOANS CONVERTED TO TERM LOANS	12.9	5.1
TOTAL LOANS AND LEASES	371.5	597.9
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	11.2	23.3
2020/2019	0.0	14.9
2019/2018	30.9	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	1.1	1.8
REVOLVING LOANS	41.6	275.6
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	84.8	315.6
Personal | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	37.0	12.7
2020/2019	7.1	26.0
2019/2018	6.2	11.8
2018/2017	10.4	0.5
2017/2016	0.0	0.5
PRIOR	3.9	7.9
REVOLVING LOANS	209.0	217.5
REVOLVING LOANS CONVERTED TO TERM LOANS	12.9	5.1
TOTAL LOANS AND LEASES	286.5	282.0
Personal | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.0	0.0
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.2	0.3
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	0.2	0.3
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	168.4	49.0
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	168.4	49.0
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	146.7	34.6
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	146.7	34.6
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	21.7	14.4
2020/2019	0.0	0.0
2019/2018	0.0	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	$ 21.7	$ 14.4