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Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Capital Expenditures	$ 10,578	$ 27,120
Depreciation	8,309	7,473
Amortization	14,352	13,077
Operating Segments
Segment Reporting Information [Line Items]
Capital Expenditures	10,418	26,123
Depreciation	7,978	7,217
Amortization	14,294	13,020
Operating Segments | Private Banks
Segment Reporting Information [Line Items]
Capital Expenditures	5,829	9,925
Depreciation	4,132	3,882
Amortization	8,576	7,421
Operating Segments | Investment Advisors
Segment Reporting Information [Line Items]
Capital Expenditures	2,308	5,390
Depreciation	1,289	1,151
Amortization	2,627	2,652
Operating Segments | Institutional Investors
Segment Reporting Information [Line Items]
Capital Expenditures	511	1,358
Depreciation	358	302
Amortization	426	427
Operating Segments | Investment Managers
Segment Reporting Information [Line Items]
Capital Expenditures	1,631	9,032
Depreciation	2,053	1,812
Amortization	2,480	2,335
Operating Segments | Investments In New Businesses
Segment Reporting Information [Line Items]
Capital Expenditures	139	418
Depreciation	146	70
Amortization	185	185
Corporate
Segment Reporting Information [Line Items]
Capital Expenditures	160	997
Depreciation	331	256
Amortization	$ 58	$ 57

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The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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