Loans (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	$ 6,596.2		$ 6,596.2		$ 7,905.6
2022/2021	5,376.5		5,376.5		5,484.1
2021/2020	4,603.5		4,603.5		2,791.4
2020/2019	1,949.4		1,949.4		2,007.3
2019/2018	1,306.4		1,306.4		746.1
PRIOR	2,994.5		2,994.5		3,012.1
REVOLVING LOANS	20,032.1		20,032.1		20,561.7
REVOLVING LOANS CONVERTED TO TERM LOANS	688.1		688.1		385.0
TOTAL LOANS	43,546.7		43,546.7		42,893.3
2023, Charge-offs			(0.7)
2022, Charge-offs			(4.0)
2021, Charge-offs			0.0
2020, Charge-offs			0.0
2019, 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	(0.8)	$ 0.0	(4.8)	$ (0.1)
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	5,875.5		5,875.5		5,610.6
2022/2021	3,126.4		3,126.4		3,194.9
2021/2020	2,513.8		2,513.8		1,381.6
2020/2019	664.0		664.0		1,021.9
2019/2018	656.7		656.7		390.1
PRIOR	1,028.3		1,028.3		1,203.4
REVOLVING LOANS	8,401.5		8,401.5		8,760.2
REVOLVING LOANS CONVERTED TO TERM LOANS	95.0		95.0		72.9
TOTAL LOANS	22,361.2		22,361.2		21,635.6
2023, Charge-offs			0.0
2022, Charge-offs			(4.0)
2021, Charge-offs			0.0
2020, Charge-offs			0.0
2019, 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	0.0	0.0	(4.0)	0.0
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	834.0		834.0		1,548.2
2022/2021	1,498.7		1,498.7		1,858.6
2021/2020	1,654.2		1,654.2		510.6
2020/2019	264.1		264.1		364.1
2019/2018	282.4		282.4		197.3
PRIOR	613.5		613.5		686.0
REVOLVING LOANS	7,014.8		7,014.8		7,199.6
REVOLVING LOANS CONVERTED TO TERM LOANS	77.3		77.3		50.6
TOTAL LOANS	12,239.0		12,239.0		12,415.0
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	230.2		230.2		753.3
2022/2021	623.3		623.3		1,087.5
2021/2020	941.2		941.2		209.8
2020/2019	98.1		98.1		159.3
2019/2018	140.8		140.8		45.9
PRIOR	404.8		404.8		511.3
REVOLVING LOANS	5,310.4		5,310.4		6,032.8
REVOLVING LOANS CONVERTED TO TERM LOANS	15.0		15.0		17.7
TOTAL LOANS	7,763.8		7,763.8		8,817.6
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	600.0		600.0		744.1
2022/2021	782.0		782.0		740.6
2021/2020	683.9		683.9		300.8
2020/2019	166.0		166.0		191.1
2019/2018	141.4		141.4		151.4
PRIOR	207.0		207.0		174.7
REVOLVING LOANS	1,677.3		1,677.3		1,102.3
REVOLVING LOANS CONVERTED TO TERM LOANS	62.3		62.3		32.9
TOTAL LOANS	4,319.9		4,319.9		3,437.9
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	3.8		3.8		50.8
2022/2021	93.4		93.4		30.5
2021/2020	29.1		29.1		0.0
2020/2019	0.0		0.0		13.7
2019/2018	0.2		0.2		0.0
PRIOR	1.7		1.7		0.0
REVOLVING LOANS	27.1		27.1		64.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	155.3		155.3		159.5
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1,486.5		1,486.5		1,294.9
2022/2021	1,605.1		1,605.1		1,290.1
2021/2020	814.6		814.6		761.4
2020/2019	301.6		301.6		619.9
2019/2018	306.3		306.3		192.8
PRIOR	241.4		241.4		296.0
REVOLVING LOANS	268.7		268.7		297.4
REVOLVING LOANS CONVERTED TO TERM LOANS	15.9		15.9		20.5
TOTAL LOANS	5,040.1		5,040.1		4,773.0
2023, Charge-offs			0.0
2022, Charge-offs			(4.0)
2021, Charge-offs			0.0
2020, Charge-offs			0.0
2019, 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			(4.0)
Commercial | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	290.7		290.7		318.7
2022/2021	431.7		431.7		227.4
2021/2020	182.3		182.3		123.6
2020/2019	26.3		26.3		123.5
2019/2018	40.4		40.4		39.8
PRIOR	59.1		59.1		39.1
REVOLVING LOANS	53.9		53.9		113.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.5		0.5		3.0
TOTAL LOANS	1,084.9		1,084.9		988.5
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1,179.0		1,179.0		968.5
2022/2021	1,169.7		1,169.7		1,040.0
2021/2020	612.4		612.4		637.8
2020/2019	275.3		275.3		447.3
2019/2018	257.6		257.6		153.0
PRIOR	167.6		167.6		256.9
REVOLVING LOANS	212.3		212.3		181.5
REVOLVING LOANS CONVERTED TO TERM LOANS	15.4		15.4		17.5
TOTAL LOANS	3,889.3		3,889.3		3,702.5
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	16.8		16.8		7.7
2022/2021	3.7		3.7		22.7
2021/2020	19.9		19.9		0.0
2020/2019	0.0		0.0		49.1
2019/2018	8.3		8.3		0.0
PRIOR	14.7		14.7		0.0
REVOLVING LOANS	2.5		2.5		2.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	65.9		65.9		82.0
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1,306.6		1,306.6		1,451.0
2022/2021	22.6		22.6		46.2
2021/2020	45.0		45.0		109.6
2020/2019	98.3		98.3		37.9
2019/2018	68.0		68.0		0.0
PRIOR	173.4		173.4		221.4
REVOLVING LOANS	1,118.0		1,118.0		1,263.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8		1.8
TOTAL LOANS	2,833.7		2,833.7		3,131.1
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	547.1		547.1		991.9
2022/2021	0.0		0.0		46.2
2021/2020	45.0		45.0		109.6
2020/2019	98.3		98.3		14.8
2019/2018	44.9		44.9		0.0
PRIOR	3.3		3.3		6.5
REVOLVING LOANS	1,008.4		1,008.4		1,158.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	1,747.0		1,747.0		2,327.3
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	759.5		759.5		459.0
2022/2021	7.9		7.9		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	23.1		23.1		0.0
PRIOR	170.1		170.1		214.9
REVOLVING LOANS	109.6		109.6		89.5
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8		1.8
TOTAL LOANS	1,072.0		1,072.0		765.2
Commercial | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0		0.1
2022/2021	14.7		14.7		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		23.1
2019/2018	0.0		0.0		0.0
PRIOR	0.0		0.0		0.0
REVOLVING LOANS	0.0		0.0		15.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	14.7		14.7		38.6
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	2,248.4		2,248.4		1,316.5
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	2,248.4		2,248.4		1,316.5
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1,400.7		1,400.7		993.9
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	1,400.7		1,400.7		993.9
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	847.7		847.7		322.6
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	847.7		847.7		322.6
Commercial | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023, Charge-offs			(0.7)
2022, Charge-offs			0.0
2021, Charge-offs			0.0
2020, Charge-offs			0.0
2019, 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			(0.8)
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	720.7		720.7		2,295.0
2022/2021	2,250.1		2,250.1		2,289.2
2021/2020	2,089.7		2,089.7		1,409.8
2020/2019	1,285.4		1,285.4		985.4
2019/2018	649.7		649.7		356.0
PRIOR	1,966.2		1,966.2		1,808.7
REVOLVING LOANS	11,630.6		11,630.6		11,801.5
REVOLVING LOANS CONVERTED TO TERM LOANS	593.1		593.1		312.1
TOTAL LOANS	21,185.5		21,185.5		21,257.7
2023, Charge-offs			(0.7)
2022, Charge-offs			0.0
2021, Charge-offs			0.0
2020, Charge-offs			0.0
2019, 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	(0.8)	$ 0.0	(0.8)	$ (0.1)
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	253.2		253.2		826.7
2022/2021	1,013.8		1,013.8		915.0
2021/2020	778.4		778.4		243.0
2020/2019	191.6		191.6		504.9
2019/2018	183.4		183.4		70.7
PRIOR	220.5		220.5		178.5
REVOLVING LOANS	10,945.8		10,945.8		11,084.8
REVOLVING LOANS CONVERTED TO TERM LOANS	585.6		585.6		295.4
TOTAL LOANS	14,172.3		14,172.3		14,119.0
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	142.3		142.3		395.5
2022/2021	256.0		256.0		159.9
2021/2020	64.9		64.9		50.5
2020/2019	72.3		72.3		313.6
2019/2018	6.2		6.2		13.4
PRIOR	20.1		20.1		18.5
REVOLVING LOANS	5,361.1		5,361.1		5,352.5
REVOLVING LOANS CONVERTED TO TERM LOANS	177.0		177.0		28.2
TOTAL LOANS	6,099.9		6,099.9		6,332.1
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	110.9		110.9		430.3
2022/2021	757.2		757.2		755.1
2021/2020	713.5		713.5		192.4
2020/2019	119.3		119.3		191.3
2019/2018	177.2		177.2		38.7
PRIOR	182.7		182.7		160.0
REVOLVING LOANS	5,581.8		5,581.8		5,728.6
REVOLVING LOANS CONVERTED TO TERM LOANS	408.6		408.6		267.2
TOTAL LOANS	8,051.2		8,051.2		7,763.6
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0		0.9
2022/2021	0.6		0.6		0.0
2021/2020	0.0		0.0		0.1
2020/2019	0.0		0.0		0.0
2019/2018	0.0		0.0		18.6
PRIOR	17.7		17.7		0.0
REVOLVING LOANS	2.9		2.9		3.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	21.2		21.2		23.3
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	214.5		214.5		1,225.9
2022/2021	1,211.7		1,211.7		1,330.2
2021/2020	1,271.3		1,271.3		1,166.8
2020/2019	1,093.8		1,093.8		459.2
2019/2018	447.5		447.5		277.5
PRIOR	1,731.8		1,731.8		1,624.9
REVOLVING LOANS	387.3		387.3		320.1
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		8.9
TOTAL LOANS	6,357.9		6,357.9		6,413.5
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	129.0		129.0		871.6
2022/2021	622.8		622.8		666.7
2021/2020	545.0		545.0		567.7
2020/2019	409.7		409.7		168.1
2019/2018	161.7		161.7		102.9
PRIOR	793.9		793.9		750.8
REVOLVING LOANS	219.5		219.5		128.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		7.9
TOTAL LOANS	2,881.6		2,881.6		3,264.1
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	85.5		85.5		354.3
2022/2021	584.2		584.2		656.7
2021/2020	720.7		720.7		597.6
2020/2019	681.9		681.9		290.0
2019/2018	275.0		275.0		170.9
PRIOR	902.4		902.4		838.2
REVOLVING LOANS	164.2		164.2		180.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		1.0
TOTAL LOANS	3,413.9		3,413.9		3,089.1
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0		0.0
2022/2021	4.7		4.7		6.8
2021/2020	5.6		5.6		1.5
2020/2019	2.2		2.2		1.1
2019/2018	10.8		10.8		3.7
PRIOR	35.5		35.5		35.9
REVOLVING LOANS	3.6		3.6		11.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	62.4		62.4		60.3
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	12.7		12.7		27.2
2022/2021	24.6		24.6		44.0
2021/2020	40.0		40.0		0.0
2020/2019	0.0		0.0		21.3
2019/2018	18.8		18.8		7.8
PRIOR	13.9		13.9		5.3
REVOLVING LOANS	297.5		297.5		396.6
REVOLVING LOANS CONVERTED TO TERM LOANS	7.5		7.5		7.8
TOTAL LOANS	415.0		415.0		510.0
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	3.9		3.9		3.0
2022/2021	4.0		4.0		3.7
2021/2020	0.6		0.6		0.0
2020/2019	0.0		0.0		0.0
2019/2018	0.0		0.0		4.6
PRIOR	5.6		5.6		2.3
REVOLVING LOANS	54.5		54.5		124.6
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	68.6		68.6		138.2
Personal | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	8.8		8.8		24.2
2022/2021	20.6		20.6		40.3
2021/2020	39.4		39.4		0.0
2020/2019	0.0		0.0		21.3
2019/2018	18.8		18.8		3.2
PRIOR	8.2		8.2		2.9
REVOLVING LOANS	243.0		243.0		272.0
REVOLVING LOANS CONVERTED TO TERM LOANS	7.5		7.5		7.8
TOTAL LOANS	346.3		346.3		371.7
Personal | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0		0.0
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	0.0		0.0		0.0
PRIOR	0.1		0.1		0.1
REVOLVING LOANS	0.0		0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0		0.0
TOTAL LOANS	0.1		0.1		0.1
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	240.3		240.3		215.2
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	240.3		240.3		215.2
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	78.1		78.1		190.8
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	78.1		78.1		190.8
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	162.2		162.2		24.4
2022/2021	0.0		0.0		0.0
2021/2020	0.0		0.0		0.0
2020/2019	0.0		0.0		0.0
2019/2018	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	$ 162.2		$ 162.2		$ 24.4