Loans and Leases (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	$ 4,926.7	$ 7,448.6
2020/2019	5,506.5	3,667.9
2019/2018	3,021.3	1,352.6
2018/2017	1,155.5	1,123.1
2017/2016	858.6	1,254.8
PRIOR	3,491.2	3,128.5
REVOLVING LOANS	18,166.9	15,453.6
REVOLVING LOANS CONVERTED TO TERM LOANS	279.9	330.6
TOTAL LOANS AND LEASES	37,406.6	33,759.7
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	3,402.7	3,772.7
2020/2019	2,361.3	2,187.7
2019/2018	1,801.3	990.3
2018/2017	864.6	725.0
2017/2016	556.0	749.9
PRIOR	1,613.5	1,285.8
REVOLVING LOANS	5,558.2	5,490.9
REVOLVING LOANS CONVERTED TO TERM LOANS	50.1	59.7
TOTAL LOANS AND LEASES	16,207.7	15,262.0
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,152.3	1,491.5
2020/2019	1,114.9	1,170.9
2019/2018	804.2	596.0
2018/2017	527.3	544.2
2017/2016	394.2	553.6
PRIOR	882.7	622.1
REVOLVING LOANS	4,923.5	5,042.2
REVOLVING LOANS CONVERTED TO TERM LOANS	34.7	37.8
TOTAL LOANS AND LEASES	9,833.8	10,058.3
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	524.2	663.8
2020/2019	654.2	546.0
2019/2018	323.0	204.6
2018/2017	218.5	96.0
2017/2016	101.5	396.0
PRIOR	606.7	448.8
REVOLVING LOANS	3,701.9	3,742.4
REVOLVING LOANS CONVERTED TO TERM LOANS	1.0	5.5
TOTAL LOANS AND LEASES	6,131.0	6,103.1
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	598.5	793.4
2020/2019	432.9	505.1
2019/2018	409.5	354.1
2018/2017	277.3	405.4
2017/2016	267.7	134.6
PRIOR	253.1	167.3
REVOLVING LOANS	1,163.7	1,238.7
REVOLVING LOANS CONVERTED TO TERM LOANS	33.7	32.3
TOTAL LOANS AND LEASES	3,436.4	3,630.9
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	29.6	34.3
2020/2019	27.8	119.8
2019/2018	71.7	37.3
2018/2017	31.5	42.8
2017/2016	25.0	23.0
PRIOR	22.9	6.0
REVOLVING LOANS	57.9	61.1
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	266.4	324.3
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	642.2	1,124.7
2020/2019	1,057.3	976.2
2019/2018	956.3	392.3
2018/2017	335.3	169.7
2017/2016	150.7	196.3
PRIOR	611.3	494.4
REVOLVING LOANS	177.2	184.7
REVOLVING LOANS CONVERTED TO TERM LOANS	13.6	20.1
TOTAL LOANS AND LEASES	3,943.9	3,558.4
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	247.4	406.3
2020/2019	278.2	109.2
2019/2018	242.9	27.6
2018/2017	78.8	36.5
2017/2016	25.5	11.8
PRIOR	95.7	99.4
REVOLVING LOANS	110.4	124.3
REVOLVING LOANS CONVERTED TO TERM LOANS	2.7	8.7
TOTAL LOANS AND LEASES	1,081.6	823.8
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	375.1	703.1
2020/2019	772.8	811.8
2019/2018	658.1	332.7
2018/2017	243.2	107.4
2017/2016	104.9	184.5
PRIOR	504.5	382.8
REVOLVING LOANS	66.8	60.4
REVOLVING LOANS CONVERTED TO TERM LOANS	10.9	11.4
TOTAL LOANS AND LEASES	2,736.3	2,594.1
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	19.7	15.3
2020/2019	6.3	55.2
2019/2018	55.3	32.0
2018/2017	13.3	25.8
2017/2016	20.3	0.0
PRIOR	11.1	12.2
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	126.0	140.5
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,280.3	868.3
2020/2019	189.1	40.6
2019/2018	40.8	2.0
2018/2017	2.0	11.1
2017/2016	11.1	0.0
PRIOR	108.5	157.9
REVOLVING LOANS	457.5	264.0
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8	1.8
TOTAL LOANS AND LEASES	2,091.1	1,345.7
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	910.6	555.2
2020/2019	87.1	16.8
2019/2018	17.0	0.0
2018/2017	0.0	11.1
2017/2016	11.1	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	318.0	78.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	1,343.8	661.6
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	369.6	313.1
2020/2019	102.0	0.7
2019/2018	0.7	2.0
2018/2017	2.0	0.0
2017/2016	0.0	0.0
PRIOR	108.5	157.9
REVOLVING LOANS	136.2	39.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8	1.8
TOTAL LOANS AND LEASES	720.8	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	3.3	146.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	26.5	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	327.9	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	327.9	288.2
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	120.4	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	120.4	81.7
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	207.5	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	207.5	206.5
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	1,524.0	3,675.9
2020/2019	3,145.2	1,480.2
2019/2018	1,220.0	362.3
2018/2017	290.9	398.1
2017/2016	302.6	504.9
PRIOR	1,877.7	1,842.7
REVOLVING LOANS	12,608.7	9,962.7
REVOLVING LOANS CONVERTED TO TERM LOANS	229.8	270.9
TOTAL LOANS AND LEASES	21,198.9	18,497.7
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	463.9	1,166.7
2020/2019	905.1	754.1
2019/2018	625.1	191.1
2018/2017	154.7	124.0
2017/2016	96.1	87.7
PRIOR	231.5	213.6
REVOLVING LOANS	11,946.0	9,021.2
REVOLVING LOANS CONVERTED TO TERM LOANS	214.3	256.7
TOTAL LOANS AND LEASES	14,636.7	11,815.1
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	198.4	668.6
2020/2019	336.7	273.7
2019/2018	101.1	51.7
2018/2017	38.4	60.4
2017/2016	70.0	10.2
PRIOR	155.1	136.1
REVOLVING LOANS	7,958.9	5,392.8
REVOLVING LOANS CONVERTED TO TERM LOANS	51.0	47.9
TOTAL LOANS AND LEASES	8,909.6	6,641.4
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	264.5	492.1
2020/2019	563.0	479.9
2019/2018	524.0	117.3
2018/2017	95.0	60.4
2017/2016	26.1	77.5
PRIOR	76.4	77.5
REVOLVING LOANS	3,984.1	3,564.7
REVOLVING LOANS CONVERTED TO TERM LOANS	163.3	207.3
TOTAL LOANS AND LEASES	5,696.4	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	21.3	3.2
2017/2016	0.0	0.0
PRIOR	0.0	0.0
REVOLVING LOANS	3.0	63.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	1.5
TOTAL LOANS AND LEASES	30.7	97.0
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	935.0	2,424.2
2020/2019	2,232.6	685.2
2019/2018	555.6	159.4
2018/2017	125.5	273.6
2017/2016	206.5	416.7
PRIOR	1,638.7	1,619.1
REVOLVING LOANS	404.8	448.4
REVOLVING LOANS CONVERTED TO TERM LOANS	1.9	9.1
TOTAL LOANS AND LEASES	6,100.6	6,035.7
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	682.2	1,554.3
2020/2019	1,300.3	317.4
2019/2018	251.0	42.9
2018/2017	19.9	109.9
2017/2016	89.3	205.1
PRIOR	707.1	627.8
REVOLVING LOANS	158.9	152.8
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	1.7
TOTAL LOANS AND LEASES	3,208.7	3,011.9
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	252.5	854.6
2020/2019	919.2	359.5
2019/2018	296.6	115.8
2018/2017	105.0	163.2
2017/2016	116.7	209.7
PRIOR	856.3	896.5
REVOLVING LOANS	229.9	273.1
REVOLVING LOANS CONVERTED TO TERM LOANS	1.9	7.4
TOTAL LOANS AND LEASES	2,778.1	2,879.8
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	0.3	15.3
2020/2019	13.1	8.3
2019/2018	8.0	0.7
2018/2017	0.6	0.5
2017/2016	0.5	1.9
PRIOR	75.3	94.8
REVOLVING LOANS	16.0	22.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	113.8	144.0
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	49.0	36.0
2020/2019	7.5	40.9
2019/2018	39.3	11.8
2018/2017	10.7	0.5
2017/2016	0.0	0.5
PRIOR	7.5	10.0
REVOLVING LOANS	257.9	493.1
REVOLVING LOANS CONVERTED TO TERM LOANS	13.6	5.1
TOTAL LOANS AND LEASES	385.5	597.9
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	12.0	23.3
2020/2019	3.7	14.9
2019/2018	31.7	0.0
2018/2017	0.0	0.0
2017/2016	0.0	0.0
PRIOR	0.1	1.8
REVOLVING LOANS	78.7	275.6
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS AND LEASES	126.2	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	3.8	26.0
2019/2018	7.6	11.8
2018/2017	10.7	0.5
2017/2016	0.0	0.5
PRIOR	7.2	7.9
REVOLVING LOANS	179.2	217.5
REVOLVING LOANS CONVERTED TO TERM LOANS	13.6	5.1
TOTAL LOANS AND LEASES	259.1	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	76.1	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	76.1	49.0
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2021/2020	54.4	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	54.4	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