Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Capital Expenditures	$ 19,855	$ 20,173	$ 46,975	$ 37,427
Depreciation	7,640	7,422	15,113	14,753
Amortization	13,140	12,781	26,217	25,460
Operating Segments
Segment Reporting Information [Line Items]
Capital Expenditures	19,057	19,587	45,180	36,456
Depreciation	7,383	7,094	14,600	14,089
Amortization	13,082	12,725	26,102	25,346
Operating Segments | Private Banks
Segment Reporting Information [Line Items]
Capital Expenditures	6,634	8,761	16,559	17,222
Depreciation	3,965	3,585	7,847	7,134
Amortization	7,464	7,217	14,885	14,358
Operating Segments | Investment Advisors
Segment Reporting Information [Line Items]
Capital Expenditures	3,803	4,558	9,193	8,505
Depreciation	1,172	1,165	2,323	2,344
Amortization	2,664	2,550	5,316	5,073
Operating Segments | Institutional Investors
Segment Reporting Information [Line Items]
Capital Expenditures	1,029	1,049	2,387	1,920
Depreciation	301	414	603	819
Amortization	427	427	854	860
Operating Segments | Investment Managers
Segment Reporting Information [Line Items]
Capital Expenditures	7,259	4,875	16,291	8,224
Depreciation	1,869	1,820	3,681	3,591
Amortization	2,342	2,346	4,677	4,685
Operating Segments | Investments In New Businesses
Segment Reporting Information [Line Items]
Capital Expenditures	332	344	750	585
Depreciation	76	110	146	201
Amortization	185	185	370	370
Corporate
Segment Reporting Information [Line Items]
Capital Expenditures	798	586	1,795	971
Depreciation	257	328	513	664
Amortization	$ 58	$ 56	$ 115	$ 114