Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Capital Expenditures	$ 14,778	$ 19,909	$ 61,753	$ 57,336
Depreciation	7,945	7,409	23,058	22,162
Amortization	13,200	12,947	39,417	38,407
Operating Segments
Segment Reporting Information [Line Items]
Capital Expenditures	14,504	19,246	59,684	55,702
Depreciation	7,690	7,089	22,290	21,178
Amortization	13,143	12,890	39,245	38,236
Operating Segments | Private Banks
Segment Reporting Information [Line Items]
Capital Expenditures	7,652	8,018	24,211	25,240
Depreciation	4,222	3,640	12,069	10,774
Amortization	7,505	7,322	22,390	21,680
Operating Segments | Investment Advisors
Segment Reporting Information [Line Items]
Capital Expenditures	3,234	4,468	12,427	12,973
Depreciation	1,255	1,162	3,578	3,506
Amortization	2,683	2,609	7,999	7,682
Operating Segments | Institutional Investors
Segment Reporting Information [Line Items]
Capital Expenditures	698	1,070	3,085	2,990
Depreciation	298	393	901	1,212
Amortization	426	440	1,280	1,300
Operating Segments | Investment Managers
Segment Reporting Information [Line Items]
Capital Expenditures	2,776	5,311	19,067	13,535
Depreciation	1,818	1,793	5,499	5,384
Amortization	2,343	2,334	7,020	7,019
Operating Segments | Investments In New Businesses
Segment Reporting Information [Line Items]
Capital Expenditures	144	379	894	964
Depreciation	97	101	243	302
Amortization	186	185	556	555
Corporate
Segment Reporting Information [Line Items]
Capital Expenditures	274	663	2,069	1,634
Depreciation	255	320	768	984
Amortization	$ 57	$ 57	$ 172	$ 171