Loans (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	$ 7,050.0		$ 7,050.0		$ 7,843.0
Year two	3,419.7		3,419.7		3,122.0
Year three	2,831.6		2,831.6		2,591.3
Year four	2,167.3		2,167.3		2,759.6
Year five	2,345.5		2,345.5		2,137.0
PRIOR	4,589.8		4,589.8		3,341.4
REVOLVING LOANS	20,750.9		20,750.9		19,439.0
REVOLVING LOANS CONVERTED TO TERM LOANS	667.2		667.2		715.0
TOTAL LOANS	43,822.0		43,822.0		41,948.3
Year one, Charge-offs			0.0		(0.2)
Year two, Charge-offs			0.0		0.0
Year three, Charge-offs			0.0		0.0
Year four, Charge-offs			(0.2)		(2.1)
Year five, Charge-offs			0.0		0.0
Prior, Charge-offs			(0.4)		(1.6)
REVOLVING LOANS, Charge-offs			0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs			0.0		0.0
Charge-Offs	(0.2)	$ (0.1)	(0.6)	$ (0.4)	(3.9)
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	5,825.2		5,825.2		6,400.0
Year two	2,174.9		2,174.9		1,999.8
Year three	1,815.6		1,815.6		1,936.6
Year four	1,613.9		1,613.9		1,459.7
Year five	1,157.0		1,157.0		914.3
PRIOR	1,259.1		1,259.1		774.8
REVOLVING LOANS	7,394.9		7,394.9		6,819.3
REVOLVING LOANS CONVERTED TO TERM LOANS	122.7		122.7		126.5
TOTAL LOANS	21,363.3		21,363.3		20,431.0
Year one, Charge-offs			0.0		0.0
Year two, Charge-offs			0.0		0.0
Year three, Charge-offs			0.0		0.0
Year four, Charge-offs			0.0		(2.1)
Year five, Charge-offs			0.0		0.0
Prior, Charge-offs			(0.4)		(1.4)
REVOLVING LOANS, Charge-offs			0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs			0.0		0.0
Charge-Offs	0.0	0.0	(0.4)	(0.3)	(3.5)
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	429.4		429.4		927.1
Year two	963.7		963.7		1,106.5
Year three	1,004.5		1,004.5		492.0
Year four	422.9		422.9		515.3
Year five	318.6		318.6		352.7
PRIOR	375.2		375.2		268.8
REVOLVING LOANS	3,161.8		3,161.8		2,829.3
REVOLVING LOANS CONVERTED TO TERM LOANS	99.9		99.9		103.6
TOTAL LOANS	6,776.0		6,776.0		6,595.3
Year one, Charge-offs			0.0		0.0
Year two, Charge-offs			0.0		0.0
Year three, Charge-offs			0.0		0.0
Year four, Charge-offs			0.0		0.0
Year five, Charge-offs			0.0		0.0
Prior, Charge-offs			(0.4)		(1.4)
REVOLVING LOANS, Charge-offs			0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs			0.0		0.0
Charge-Offs			(0.4)		(1.4)
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	105.6		105.6		276.9
Year two	381.0		381.0		425.1
Year three	379.6		379.6		87.8
Year four	68.3		68.3		205.4
Year five	43.2		43.2		111.8
PRIOR	165.2		165.2		149.5
REVOLVING LOANS	1,156.7		1,156.7		1,205.7
REVOLVING LOANS CONVERTED TO TERM LOANS	57.2		57.2		57.6
TOTAL LOANS	2,356.8		2,356.8		2,519.8
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	323.8		323.8		561.4
Year two	542.5		542.5		661.5
Year three	590.8		590.8		353.9
Year four	310.3		310.3		263.7
Year five	246.1		246.1		219.0
PRIOR	206.7		206.7		116.6
REVOLVING LOANS	1,925.1		1,925.1		1,566.1
REVOLVING LOANS CONVERTED TO TERM LOANS	27.9		27.9		35.7
TOTAL LOANS	4,173.2		4,173.2		3,777.9
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0.0		0.0		88.8
Year two	40.2		40.2		19.9
Year three	34.1		34.1		50.3
Year four	44.3		44.3		46.2
Year five	29.3		29.3		21.9
PRIOR	3.3		3.3		2.7
REVOLVING LOANS	80.0		80.0		57.5
REVOLVING LOANS CONVERTED TO TERM LOANS	14.8		14.8		10.3
TOTAL LOANS	246.0		246.0		297.6
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	540.6		540.6		1,137.1
Year two	1,200.9		1,200.9		755.5
Year three	720.6		720.6		1,412.7
Year four	1,151.5		1,151.5		929.5
Year five	838.4		838.4		561.6
PRIOR	633.8		633.8		219.9
REVOLVING LOANS	207.6		207.6		233.0
REVOLVING LOANS CONVERTED TO TERM LOANS	22.8		22.8		22.9
TOTAL LOANS	5,316.2		5,316.2		5,272.2
Year one, Charge-offs					0.0
Year two, Charge-offs					0.0
Year three, Charge-offs					0.0
Year four, Charge-offs					(2.1)
Year five, Charge-offs					0.0
Prior, Charge-offs					0.0
REVOLVING LOANS, Charge-offs					0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs					0.0
Charge-Offs					(2.1)
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	80.8		80.8		118.5
Year two	198.5		198.5		98.7
Year three	83.0		83.0		80.8
Year four	52.5		52.5		52.6
Year five	36.5		36.5		157.3
PRIOR	138.3		138.3		20.8
REVOLVING LOANS	14.3		14.3		37.9
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	603.9		603.9		566.6
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	459.8		459.8		946.7
Year two	930.5		930.5		654.8
Year three	605.9		605.9		1,325.1
Year four	1,083.9		1,083.9		831.4
Year five	763.7		763.7		404.3
PRIOR	491.4		491.4		198.7
REVOLVING LOANS	193.3		193.3		195.1
REVOLVING LOANS CONVERTED TO TERM LOANS	22.8		22.8		22.9
TOTAL LOANS	4,551.3		4,551.3		4,579.0
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0.0		0.0		71.9
Year two	71.9		71.9		2.0
Year three	31.7		31.7		6.8
Year four	15.1		15.1		45.5
Year five	38.2		38.2		0.0
PRIOR	4.1		4.1		0.4
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	161.0		161.0		126.6
Commercial | Subscription Finance
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	529.6		529.6		281.3
Year two	1.8		1.8		68.0
Year three	90.5		90.5		31.5
Year four	39.1		39.1		0.0
Year five	0.0		0.0		0.0
PRIOR	71.7		71.7		74.9
REVOLVING LOANS	3,455.1		3,455.1		3,147.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	4,187.8		4,187.8		3,603.4
Commercial | Subscription Finance | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	518.4		518.4		281.3
Year two	0.0		0.0		68.0
Year three	90.5		90.5		15.4
Year four	12.8		12.8		0.0
Year five	0.0		0.0		0.0
PRIOR	71.7		71.7		74.9
REVOLVING LOANS	3,071.2		3,071.2		2,879.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	3,764.6		3,764.6		3,318.9
Commercial | Subscription Finance | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	11.2		11.2		0.0
Year two	1.8		1.8		0.0
Year three	0.0		0.0		16.1
Year four	26.3		26.3		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	381.8		381.8		268.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	421.1		421.1		284.5
Commercial | Subscription Finance | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0.0		0.0
Year two	0.0		0.0
Year three	0.0		0.0
Year four	0.0		0.0
Year five	0.0		0.0
PRIOR	0.0		0.0
REVOLVING LOANS	2.1		2.1
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	2.1		2.1
Commercial | Fund Finance
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	933.1		933.1		726.9
Year two	8.5		8.5		0.0
Year three	0.0		0.0		0.4
Year four	0.4		0.4		14.9
Year five	0.0		0.0		0.0
PRIOR	32.1		32.1		37.6
REVOLVING LOANS	570.4		570.4		577.9
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	1,544.5		1,544.5		1,357.7
Commercial | Fund Finance | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	553.9		553.9		322.6
Year two	0.0		0.0		0.0
Year three	0.0		0.0		0.0
Year four	0.4		0.4		14.9
Year five	0.0		0.0		0.0
PRIOR	32.1		32.1		37.6
REVOLVING LOANS	341.3		341.3		443.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	927.7		927.7		818.8
Commercial | Fund Finance | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	379.2		379.2		404.3
Year two	8.5		8.5		0.0
Year three	0.0		0.0		0.4
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	229.1		229.1		134.2
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	616.8		616.8		538.9
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	3,392.5		3,392.5		3,327.6
Year two	0.0		0.0		69.8
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	146.3		146.3		173.6
REVOLVING LOANS	0.0		0.0		31.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	3,538.8		3,538.8		3,602.4
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	1,846.2		1,846.2		1,886.3
Year two	0.0		0.0		51.2
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		24.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	1,846.2		1,846.2		1,961.9
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	1,543.1		1,543.1		1,440.3
Year two	0.0		0.0		18.6
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	146.3		146.3		173.6
REVOLVING LOANS	0.0		0.0		7.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	1,689.4		1,689.4		1,639.5
Commercial | Other | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	3.2		3.2		1.0
Year two	0.0		0.0		0.0
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	3.2		3.2		1.0
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	1,224.8		1,224.8		1,443.0
Year two	1,244.8		1,244.8		1,122.2
Year three	1,016.0		1,016.0		654.7
Year four	553.4		553.4		1,299.9
Year five	1,188.5		1,188.5		1,222.7
PRIOR	3,330.7		3,330.7		2,566.6
REVOLVING LOANS	13,356.0		13,356.0		12,619.7
REVOLVING LOANS CONVERTED TO TERM LOANS	544.5		544.5		588.5
TOTAL LOANS	22,458.7		22,458.7		21,517.3
Year one, Charge-offs			0.0		(0.2)
Year two, Charge-offs			0.0		0.0
Year three, Charge-offs			0.0		0.0
Year four, Charge-offs			(0.2)		0.0
Year five, Charge-offs			0.0		0.0
Prior, Charge-offs			0.0		(0.2)
REVOLVING LOANS, Charge-offs			0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs			0.0		0.0
Charge-Offs	(0.2)	$ (0.1)	(0.2)	$ (0.1)	(0.4)
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	372.7		372.7		601.7
Year two	640.5		640.5		719.3
Year three	649.9		649.9		289.9
Year four	231.1		231.1		372.2
Year five	325.3		325.3		198.2
PRIOR	234.4		234.4		228.8
REVOLVING LOANS	12,895.3		12,895.3		12,172.6
REVOLVING LOANS CONVERTED TO TERM LOANS	542.7		542.7		586.6
TOTAL LOANS	15,891.9		15,891.9		15,169.3
Year one, Charge-offs			0.0		0.0
Year two, Charge-offs			0.0		0.0
Year three, Charge-offs			0.0		0.0
Year four, Charge-offs			(0.2)		0.0
Year five, Charge-offs			0.0		0.0
Prior, Charge-offs			0.0		(0.1)
REVOLVING LOANS, Charge-offs			0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs			0.0		0.0
Charge-Offs			(0.2)		(0.1)
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	160.0		160.0		149.9
Year two	101.6		101.6		130.7
Year three	145.1		145.1		133.0
Year four	86.4		86.4		58.7
Year five	57.8		57.8		47.2
PRIOR	40.0		40.0		44.6
REVOLVING LOANS	5,339.9		5,339.9		5,813.0
REVOLVING LOANS CONVERTED TO TERM LOANS	83.0		83.0		38.7
TOTAL LOANS	6,013.8		6,013.8		6,415.8
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	212.7		212.7		429.2
Year two	521.8		521.8		581.0
Year three	462.3		462.3		141.7
Year four	129.8		129.8		313.5
Year five	267.5		267.5		151.0
PRIOR	194.4		194.4		184.2
REVOLVING LOANS	7,537.0		7,537.0		6,350.9
REVOLVING LOANS CONVERTED TO TERM LOANS	459.7		459.7		547.9
TOTAL LOANS	9,785.2		9,785.2		8,699.4
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0.0		0.0		22.6
Year two	17.1		17.1		7.6
Year three	42.5		42.5		15.2
Year four	14.9		14.9		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	18.4		18.4		8.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	92.9		92.9		54.1
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	335.8		335.8		614.3
Year two	604.3		604.3		402.9
Year three	366.1		366.1		364.8
Year four	322.3		322.3		927.7
Year five	863.2		863.2		1,024.5
PRIOR	3,096.3		3,096.3		2,337.8
REVOLVING LOANS	460.7		460.7		447.1
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8		1.9
TOTAL LOANS	6,050.5		6,050.5		6,121.0
Year one, Charge-offs					0.0
Year two, Charge-offs					0.0
Year three, Charge-offs					0.0
Year four, Charge-offs					0.0
Year five, Charge-offs					0.0
Prior, Charge-offs					(0.1)
REVOLVING LOANS, Charge-offs					0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs					0.0
Charge-Offs					(0.1)
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	178.2		178.2		357.1
Year two	356.6		356.6		138.7
Year three	194.7		194.7		131.8
Year four	172.8		172.8		343.3
Year five	527.7		527.7		334.6
PRIOR	1,719.1		1,719.1		993.2
REVOLVING LOANS	221.7		221.7		232.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	3,370.8		3,370.8		2,531.0
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	157.6		157.6		256.2
Year two	246.7		246.7		264.2
Year three	171.4		171.4		232.1
Year four	149.5		149.5		576.3
Year five	326.8		326.8		658.6
PRIOR	1,314.5		1,314.5		1,313.0
REVOLVING LOANS	226.8		226.8		194.3
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8		1.9
TOTAL LOANS	2,595.1		2,595.1		3,496.6
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0.0		0.0		1.0
Year two	1.0		1.0		0.0
Year three	0.0		0.0		0.9
Year four	0.0		0.0		8.1
Year five	8.7		8.7		31.3
PRIOR	62.7		62.7		31.6
REVOLVING LOANS	12.2		12.2		20.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	84.6		84.6		93.4
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	516.3		516.3		227.0
Year two	0.0		0.0		0.0
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	516.3		516.3		227.0
Year one, Charge-offs					(0.2)
Year two, Charge-offs					0.0
Year three, Charge-offs					0.0
Year four, Charge-offs					0.0
Year five, Charge-offs					0.0
Prior, Charge-offs					0.0
REVOLVING LOANS, Charge-offs					0.0
REVOLVING LOANS CONVERTED TO TERM LOANS, Charge-offs					0.0
Charge-Offs					(0.2)
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	298.9		298.9		86.0
Year two	0.0		0.0		0.0
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	298.9		298.9		86.0
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	217.4		217.4		141.0
Year two	0.0		0.0		0.0
Year three	0.0		0.0		0.0
Year four	0.0		0.0		0.0
Year five	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	$ 217.4		$ 217.4		$ 141.0