Loans (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	$ 4,213.8		$ 7,905.6
2022/2021	5,072.7		5,484.1
2021/2020	5,084.7		2,791.4
2020/2019	2,903.5		2,007.3
2019/2018	1,389.0		746.1
PRIOR	2,509.9		3,012.1
REVOLVING LOANS	20,728.1		20,561.7
REVOLVING LOANS CONVERTED TO TERM LOANS	467.8		385.0
TOTAL LOANS	42,369.5		42,893.3
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
Charge-Offs	(4.0)	$ (0.1)
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	3,636.4		5,610.6
2022/2021	2,872.9		3,194.9
2021/2020	2,744.8		1,381.6
2020/2019	1,015.5		1,021.9
2019/2018	830.3		390.1
PRIOR	1,246.7		1,203.4
REVOLVING LOANS	9,165.7		8,760.2
REVOLVING LOANS CONVERTED TO TERM LOANS	97.4		72.9
TOTAL LOANS	21,609.7		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	(4.0)	0.0
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	518.2		1,548.2
2022/2021	1,544.6		1,858.6
2021/2020	1,650.6		510.6
2020/2019	366.0		364.1
2019/2018	313.2		197.3
PRIOR	718.5		686.0
REVOLVING LOANS	7,559.4		7,199.6
REVOLVING LOANS CONVERTED TO TERM LOANS	79.7		50.6
TOTAL LOANS	12,750.2		12,415.0
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	253.4		753.3
2022/2021	695.7		1,087.5
2021/2020	907.8		209.8
2020/2019	133.6		159.3
2019/2018	138.8		45.9
PRIOR	459.7		511.3
REVOLVING LOANS	6,388.9		6,032.8
REVOLVING LOANS CONVERTED TO TERM LOANS	17.5		17.7
TOTAL LOANS	8,995.4		8,817.6
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	263.6		744.1
2022/2021	820.2		740.6
2021/2020	705.1		300.8
2020/2019	232.4		191.1
2019/2018	164.7		151.4
PRIOR	248.1		174.7
REVOLVING LOANS	1,113.4		1,102.3
REVOLVING LOANS CONVERTED TO TERM LOANS	62.2		32.9
TOTAL LOANS	3,609.7		3,437.9
Commercial | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1.2		50.8
2022/2021	28.7		30.5
2021/2020	37.7		0.0
2020/2019	0.0		13.7
2019/2018	9.7		0.0
PRIOR	10.7		0.0
REVOLVING LOANS	57.1		64.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	145.1		159.5
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	993.7		1,294.9
2022/2021	1,305.6		1,290.1
2021/2020	1,048.4		761.4
2020/2019	503.6		619.9
2019/2018	478.7		192.8
PRIOR	381.3		296.0
REVOLVING LOANS	254.2		297.4
REVOLVING LOANS CONVERTED TO TERM LOANS	15.9		20.5
TOTAL LOANS	4,981.4		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	129.5		318.7
2022/2021	253.3		227.4
2021/2020	196.6		123.6
2020/2019	48.3		123.5
2019/2018	83.5		39.8
PRIOR	62.7		39.1
REVOLVING LOANS	27.3		113.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.5		3.0
TOTAL LOANS	801.7		988.5
Commercial | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	858.8		968.5
2022/2021	1,052.3		1,040.0
2021/2020	826.3		637.8
2020/2019	455.3		447.3
2019/2018	353.1		153.0
PRIOR	308.8		256.9
REVOLVING LOANS	224.4		181.5
REVOLVING LOANS CONVERTED TO TERM LOANS	15.4		17.5
TOTAL LOANS	4,094.4		3,702.5
Commercial | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	5.4		7.7
2022/2021	0.0		22.7
2021/2020	25.5		0.0
2020/2019	0.0		49.1
2019/2018	42.1		0.0
PRIOR	9.8		0.0
REVOLVING LOANS	2.5		2.5
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	85.3		82.0
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	1,250.7		1,451.0
2022/2021	22.7		46.2
2021/2020	45.8		109.6
2020/2019	145.9		37.9
2019/2018	38.4		0.0
PRIOR	146.9		221.4
REVOLVING LOANS	1,352.1		1,263.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8
TOTAL LOANS	3,004.3		3,131.1
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	797.9		991.9
2022/2021	0.0		46.2
2021/2020	45.8		109.6
2020/2019	145.9		14.8
2019/2018	15.3		0.0
PRIOR	3.7		6.5
REVOLVING LOANS	1,125.1		1,158.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	2,133.7		2,327.3
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	452.7		459.0
2022/2021	7.9		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	0.0		0.0
PRIOR	143.2		214.9
REVOLVING LOANS	212.0		89.5
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8		1.8
TOTAL LOANS	817.6		765.2
Commercial | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.1		0.1
2022/2021	14.8		0.0
2021/2020	0.0		0.0
2020/2019	0.0		23.1
2019/2018	23.1		0.0
PRIOR	0.0		0.0
REVOLVING LOANS	15.0		15.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	53.0		38.6
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	873.8		1,316.5
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	873.8		1,316.5
Commercial | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	594.5		993.9
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	594.5		993.9
Commercial | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	279.3		322.6
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	279.3		322.6
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	577.4		2,295.0
2022/2021	2,199.8		2,289.2
2021/2020	2,339.9		1,409.8
2020/2019	1,888.0		985.4
2019/2018	558.7		356.0
PRIOR	1,263.2		1,808.7
REVOLVING LOANS	11,562.4		11,801.5
REVOLVING LOANS CONVERTED TO TERM LOANS	370.4		312.1
TOTAL LOANS	20,759.8		21,257.7
2023, Charge-offs	0.0
2022, Charge-offs	0.0
2021, Charge-offs	0.0
2020, Charge-offs	0.0
2019, Charge-offs	0.0
Prior, Charge-offs	0.0
Charge-Offs	0.0	$ (0.1)
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	396.6		826.7
2022/2021	896.8		915.0
2021/2020	761.6		243.0
2020/2019	210.1		504.9
2019/2018	192.2		70.7
PRIOR	206.6		178.5
REVOLVING LOANS	10,846.7		11,084.8
REVOLVING LOANS CONVERTED TO TERM LOANS	354.7		295.4
TOTAL LOANS	13,865.3		14,119.0
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	324.6		395.5
2022/2021	402.1		159.9
2021/2020	80.3		50.5
2020/2019	21.5		313.6
2019/2018	17.3		13.4
PRIOR	13.1		18.5
REVOLVING LOANS	4,952.0		5,352.5
REVOLVING LOANS CONVERTED TO TERM LOANS	71.6		28.2
TOTAL LOANS	5,882.5		6,332.1
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	72.0		430.3
2022/2021	493.8		755.1
2021/2020	681.3		192.4
2020/2019	183.6		191.3
2019/2018	174.9		38.7
PRIOR	175.3		160.0
REVOLVING LOANS	5,888.1		5,728.6
REVOLVING LOANS CONVERTED TO TERM LOANS	283.1		267.2
TOTAL LOANS	7,952.1		7,763.6
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.9
2022/2021	0.9		0.0
2021/2020	0.0		0.1
2020/2019	5.0		0.0
2019/2018	0.0		18.6
PRIOR	18.2		0.0
REVOLVING LOANS	6.6		3.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	30.7		23.3
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	92.3		1,225.9
2022/2021	1,264.7		1,330.2
2021/2020	1,536.9		1,166.8
2020/2019	1,676.9		459.2
2019/2018	347.3		277.5
PRIOR	1,052.6		1,624.9
REVOLVING LOANS	398.4		320.1
REVOLVING LOANS CONVERTED TO TERM LOANS	7.9		8.9
TOTAL LOANS	6,377.0		6,413.5
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	50.4		871.6
2022/2021	809.9		666.7
2021/2020	660.7		567.7
2020/2019	772.4		168.1
2019/2018	147.1		102.9
PRIOR	390.6		750.8
REVOLVING LOANS	208.9		128.4
REVOLVING LOANS CONVERTED TO TERM LOANS	7.9		7.9
TOTAL LOANS	3,047.9		3,264.1
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	41.9		354.3
2022/2021	449.0		656.7
2021/2020	873.7		597.6
2020/2019	902.8		290.0
2019/2018	189.3		170.9
PRIOR	623.1		838.2
REVOLVING LOANS	178.2		180.4
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		1.0
TOTAL LOANS	3,258.0		3,089.1
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0
2022/2021	5.8		6.8
2021/2020	2.5		1.5
2020/2019	1.7		1.1
2019/2018	10.9		3.7
PRIOR	38.9		35.9
REVOLVING LOANS	11.3		11.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	71.1		60.3
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		27.2
2022/2021	38.3		44.0
2021/2020	41.4		0.0
2020/2019	1.0		21.3
2019/2018	19.2		7.8
PRIOR	4.0		5.3
REVOLVING LOANS	317.3		396.6
REVOLVING LOANS CONVERTED TO TERM LOANS	7.8		7.8
TOTAL LOANS	429.0		510.0
Personal | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		3.0
2022/2021	12.3		3.7
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	0.0		4.6
PRIOR	1.0		2.3
REVOLVING LOANS	47.8		124.6
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	61.1		138.2
Personal | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		24.2
2022/2021	26.0		40.3
2021/2020	41.4		0.0
2020/2019	1.0		21.3
2019/2018	19.2		3.2
PRIOR	2.9		2.9
REVOLVING LOANS	269.5		272.0
REVOLVING LOANS CONVERTED TO TERM LOANS	7.8		7.8
TOTAL LOANS	367.8		371.7
Personal | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	0.0		0.0
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	0.0		0.0
PRIOR	0.1		0.1
REVOLVING LOANS	0.0		0.0
REVOLVING LOANS CONVERTED TO TERM LOANS	0.0		0.0
TOTAL LOANS	0.1		0.1
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	88.5		215.2
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	88.5		215.2
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	28.9		190.8
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	28.9		190.8
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2023/2022	59.6		24.4
2022/2021	0.0		0.0
2021/2020	0.0		0.0
2020/2019	0.0		0.0
2019/2018	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	$ 59.6		$ 24.4