Loans (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	$ 6,875.8	$ 13,006.4
Loans originated, year two	3,905.4	4,823.9
Loans originated, year three	3,835.4	4,177.6
Loans originated, year four	3,176.8	1,765.4
Loans originated, year five	1,540.2	1,208.7
PRIOR	2,664.7	2,681.5
REVOLVING LOANS	20,656.1	19,233.5
REVOLVING LOANS CONVERTED TO TERM LOANS	736.2	720.0
TOTAL LOANS	43,390.6	47,617.0
Charge-offs, year one	0.0	(2.1)
Charge-offs, year two	(7.3)	(4.4)
Charge-offs, year three	(7.8)	0.0
Charge-offs, year four	0.0	0.0
Charge-offs, year five	0.0	0.0
Charge-offs, prior	(0.4)	(1.0)
Charge-offs, revolving loans	0.0	0.0
Charge-offs, revolving loans converted to term loans	0.0	0.0
Charge-offs	(15.5)	(7.5)	$ (6.0)
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	5,454.6	10,601.2
Loans originated, year two	2,764.1	3,008.8
Loans originated, year three	2,261.1	2,212.4
Loans originated, year four	1,624.2	536.3
Loans originated, year five	428.7	590.8
PRIOR	698.9	899.0
REVOLVING LOANS	6,948.9	7,467.6
REVOLVING LOANS CONVERTED TO TERM LOANS	98.3	96.7
TOTAL LOANS	20,278.8	25,412.8
Charge-offs, year one	0.0	(1.3)
Charge-offs, year two	(7.3)	(4.4)
Charge-offs, year three	(7.8)	0.0
Charge-offs, year four	0.0	0.0
Charge-offs, year five	0.0	0.0
Charge-offs, prior	0.0	0.0
Charge-offs, revolving loans	0.0	0.0
Charge-offs, revolving loans converted to term loans	0.0	0.0
Charge-offs	(15.1)	(5.7)	(5.3)
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1,205.2	1,259.1
Loans originated, year two	833.9	1,395.0
Loans originated, year three	826.2	1,458.6
Loans originated, year four	964.7	228.8
Loans originated, year five	166.8	257.8
PRIOR	423.7	590.3
REVOLVING LOANS	6,023.5	6,276.9
REVOLVING LOANS CONVERTED TO TERM LOANS	93.1	88.8
TOTAL LOANS	10,537.1	11,555.3
Charge-offs, year one	0.0
Charge-offs, year two	(7.3)
Charge-offs, year three	(5.4)
Charge-offs, year four	0.0
Charge-offs, year five	0.0
Charge-offs, prior	0.0
Charge-offs, revolving loans	0.0
Charge-offs, revolving loans converted to term loans	0.0
Charge-offs	(12.7)
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	462.1	443.9
Loans originated, year two	238.2	534.1
Loans originated, year three	367.9	668.3
Loans originated, year four	466.2	78.1
Loans originated, year five	82.2	137.2
PRIOR	277.2	409.9
REVOLVING LOANS	4,364.8	4,909.8
REVOLVING LOANS CONVERTED TO TERM LOANS	26.5	15.0
TOTAL LOANS	6,285.1	7,196.3
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	708.3	801.4
Loans originated, year two	506.4	790.9
Loans originated, year three	392.5	729.5
Loans originated, year four	428.3	138.7
Loans originated, year five	82.3	120.5
PRIOR	144.2	178.7
REVOLVING LOANS	1,585.1	1,332.4
REVOLVING LOANS CONVERTED TO TERM LOANS	59.7	72.0
TOTAL LOANS	3,906.8	4,164.1
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	34.8	13.8
Loans originated, year two	89.3	70.0
Loans originated, year three	65.8	60.8
Loans originated, year four	70.2	12.0
Loans originated, year five	2.3	0.1
PRIOR	2.3	1.7
REVOLVING LOANS	73.6	34.7
REVOLVING LOANS CONVERTED TO TERM LOANS	6.9	1.8
TOTAL LOANS	345.2	194.9
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	747.3	1,933.2
Loans originated, year two	1,846.3	1,598.7
Loans originated, year three	1,420.5	710.6
Loans originated, year four	634.5	242.3
Loans originated, year five	191.3	298.8
PRIOR	218.5	155.4
REVOLVING LOANS	250.6	187.3
REVOLVING LOANS CONVERTED TO TERM LOANS	5.2	7.9
TOTAL LOANS	5,314.2	5,134.2
Charge-offs, year one	0.0	(0.7)
Charge-offs, year two	0.0	(4.4)
Charge-offs, year three	(2.4)	0.0
Charge-offs, year four	0.0	0.0
Charge-offs, year five	0.0	0.0
Charge-offs, prior	0.0	0.0
Charge-offs, revolving loans	0.0	0.0
Charge-offs, revolving loans converted to term loans	0.0	0.0
Charge-offs	(2.4)	(5.1)
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	123.2	403.6
Loans originated, year two	256.3	389.9
Loans originated, year three	224.4	159.1
Loans originated, year four	203.7	23.9
Loans originated, year five	13.8	37.8
PRIOR	43.7	44.8
REVOLVING LOANS	52.6	51.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	917.7	1,110.1
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	610.1	1,513.5
Loans originated, year two	1,574.2	1,208.8
Loans originated, year three	1,070.4	521.0
Loans originated, year four	424.8	218.4
Loans originated, year five	173.2	252.8
PRIOR	174.4	96.0
REVOLVING LOANS	198.0	136.3
REVOLVING LOANS CONVERTED TO TERM LOANS	5.2	7.9
TOTAL LOANS	4,230.3	3,954.7
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	14.0	16.1
Loans originated, year two	15.8	0.0
Loans originated, year three	125.7	30.5
Loans originated, year four	6.0	0.0
Loans originated, year five	4.3	8.2
PRIOR	0.4	14.6
REVOLVING LOANS	0.0	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	166.2	69.4
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1,188.5	1,464.1
Loans originated, year two	83.9	15.1
Loans originated, year three	14.4	43.2
Loans originated, year four	25.0	65.2
Loans originated, year five	70.6	34.2
PRIOR	56.7	153.3
REVOLVING LOANS	674.8	1,003.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	2,113.9	2,778.5
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	707.1	487.9
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	43.2
Loans originated, year four	0.0	65.2
Loans originated, year five	70.6	34.2
PRIOR	28.8	3.3
REVOLVING LOANS	614.9	760.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	1,421.4	1,393.8
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	480.5	974.7
Loans originated, year two	83.9	0.8
Loans originated, year three	0.8	0.0
Loans originated, year four	25.0	0.0
Loans originated, year five	0.0	0.0
PRIOR	27.9	150.0
REVOLVING LOANS	59.9	243.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	678.0	1,368.9
Commercial | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	0.9	1.5
Loans originated, year two	0.0	14.3
Loans originated, year three	13.6	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	14.5	15.8
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	2,313.6	5,944.8
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	2,313.6	5,944.8
Charge-offs, year one		(0.6)
Charge-offs, year two		0.0
Charge-offs, year three		0.0
Charge-offs, year four		0.0
Charge-offs, year five		0.0
Charge-offs, prior		0.0
Charge-offs, revolving loans		0.0
Charge-offs, revolving loans converted to term loans		0.0
Charge-offs		(0.6)
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1,142.4	4,313.2
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	1,142.4	4,313.2
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1,171.2	1,631.6
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	1,171.2	1,631.6
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Charge-offs, year one	0.0
Charge-offs, year two	0.0
Charge-offs, year three	0.0
Charge-offs, year four	0.0
Charge-offs, year five	0.0
Charge-offs, prior	(0.3)
Charge-offs, revolving loans	0.0
Charge-offs, revolving loans converted to term loans	0.0
Charge-offs	(0.3)
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1,421.2	2,405.2
Loans originated, year two	1,141.3	1,815.1
Loans originated, year three	1,574.3	1,965.2
Loans originated, year four	1,552.6	1,229.1
Loans originated, year five	1,111.5	617.9
PRIOR	1,965.8	1,782.5
REVOLVING LOANS	13,707.2	11,765.9
REVOLVING LOANS CONVERTED TO TERM LOANS	637.9	623.3
TOTAL LOANS	23,111.8	22,204.2
Charge-offs, year one	0.0	(0.8)
Charge-offs, year two	0.0	0.0
Charge-offs, year three	0.0	0.0
Charge-offs, year four	0.0	0.0
Charge-offs, year five	0.0	0.0
Charge-offs, prior	(0.4)	(1.0)
Charge-offs, revolving loans	0.0	0.0
Charge-offs, revolving loans converted to term loans	0.0	0.0
Charge-offs	(0.4)	(1.8)	$ (0.7)
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	500.3	818.4
Loans originated, year two	710.2	629.3
Loans originated, year three	468.4	707.4
Loans originated, year four	428.4	168.4
Loans originated, year five	131.4	167.5
PRIOR	225.9	197.7
REVOLVING LOANS	12,755.6	11,055.4
REVOLVING LOANS CONVERTED TO TERM LOANS	628.6	615.9
TOTAL LOANS	15,848.8	14,360.0
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	251.3	504.7
Loans originated, year two	33.9	140.8
Loans originated, year three	84.4	52.3
Loans originated, year four	37.9	67.5
Loans originated, year five	7.9	8.7
PRIOR	44.6	134.7
REVOLVING LOANS	6,993.2	5,320.9
REVOLVING LOANS CONVERTED TO TERM LOANS	93.3	168.1
TOTAL LOANS	7,546.5	6,397.7
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	249.0	290.1
Loans originated, year two	660.2	488.2
Loans originated, year three	384.0	655.1
Loans originated, year four	390.5	100.9
Loans originated, year five	123.5	158.8
PRIOR	181.3	44.7
REVOLVING LOANS	5,734.8	5,721.5
REVOLVING LOANS CONVERTED TO TERM LOANS	535.3	447.8
TOTAL LOANS	8,258.6	7,907.1
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	0.0	23.6
Loans originated, year two	16.1	0.3
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	0.0	0.0
PRIOR	0.0	18.3
REVOLVING LOANS	27.6	13.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	43.7	55.2
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	411.9	470.3
Loans originated, year two	414.1	1,169.8
Loans originated, year three	1,090.7	1,218.0
Loans originated, year four	1,085.1	1,060.7
Loans originated, year five	980.1	434.0
PRIOR	1,714.2	1,571.3
REVOLVING LOANS	411.7	403.0
REVOLVING LOANS CONVERTED TO TERM LOANS	2.1	0.0
TOTAL LOANS	6,109.9	6,327.1
Charge-offs, year one	0.0	(0.8)
Charge-offs, year two	0.0	0.0
Charge-offs, year three	0.0	0.0
Charge-offs, year four	0.0	0.0
Charge-offs, year five	0.0	0.0
Charge-offs, prior	(0.1)	(1.0)
Charge-offs, revolving loans	0.0	0.0
Charge-offs, revolving loans converted to term loans	0.0	0.0
Charge-offs	(0.1)	(1.8)
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	197.5	278.7
Loans originated, year two	150.5	464.0
Loans originated, year three	436.7	500.6
Loans originated, year four	375.2	373.3
Loans originated, year five	325.7	142.4
PRIOR	743.6	722.4
REVOLVING LOANS	114.3	219.8
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	2,343.5	2,701.2
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	212.7	191.6
Loans originated, year two	263.6	694.9
Loans originated, year three	647.2	717.4
Loans originated, year four	706.0	686.7
Loans originated, year five	652.1	290.0
PRIOR	938.1	805.3
REVOLVING LOANS	270.2	170.3
REVOLVING LOANS CONVERTED TO TERM LOANS	2.1	0.0
TOTAL LOANS	3,692.0	3,556.2
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	1.7	0.0
Loans originated, year two	0.0	10.9
Loans originated, year three	6.8	0.0
Loans originated, year four	3.9	0.7
Loans originated, year five	2.3	1.6
PRIOR	32.5	43.6
REVOLVING LOANS	27.2	12.9
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	74.4	69.7
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	30.6	28.2
Loans originated, year two	17.0	16.0
Loans originated, year three	15.2	39.8
Loans originated, year four	39.1	0.0
Loans originated, year five	0.0	16.4
PRIOR	25.7	13.5
REVOLVING LOANS	539.9	307.5
REVOLVING LOANS CONVERTED TO TERM LOANS	7.2	7.4
TOTAL LOANS	674.7	428.8
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	3.3	15.5
Loans originated, year two	1.0	0.0
Loans originated, year three	0.0	0.6
Loans originated, year four	0.0	0.0
Loans originated, year five	0.0	0.0
PRIOR	6.0	4.6
REVOLVING LOANS	369.6	71.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0	0.0
TOTAL LOANS	379.9	92.1
Personal | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	19.5	12.7
Loans originated, year two	16.0	16.0
Loans originated, year three	15.2	39.2
Loans originated, year four	39.1	0.0
Loans originated, year five	0.0	16.4
PRIOR	19.6	8.9
REVOLVING LOANS	170.3	236.1
REVOLVING LOANS CONVERTED TO TERM LOANS	7.2	7.4
TOTAL LOANS	286.9	336.7
Personal | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	7.8
Loans originated, year two	0.0
Loans originated, year three	0.0
Loans originated, year four	0.0
Loans originated, year five	0.0
PRIOR	0.1
REVOLVING LOANS	0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0
TOTAL LOANS	7.9
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	478.4	1,088.3
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	478.4	1,088.3
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	168.5	461.7
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	168.5	461.7
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Loans originated, year one	309.9	626.6
Loans originated, year two	0.0	0.0
Loans originated, year three	0.0	0.0
Loans originated, year four	0.0	0.0
Loans originated, year five	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	$ 309.9	$ 626.6