Business Segment Information (Schedule of Financial Information About Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 414,762	$ 400,820
Expenses	286,551	277,224
Operating profit (loss)	128,211	123,596
Private Banks
Segment Reporting Information [Line Items]
Revenues	113,221	118,259
Expenses	110,653	110,962
Operating profit (loss)	2,568	7,297
Investment Advisors
Segment Reporting Information [Line Items]
Revenues	102,321	94,761
Expenses	52,432	52,502
Operating profit (loss)	49,889	42,259
Institutional Investors
Segment Reporting Information [Line Items]
Revenues	79,203	80,113
Expenses	38,267	38,754
Operating profit (loss)	40,936	41,359
Investment Managers
Segment Reporting Information [Line Items]
Revenues	116,629	104,649
Expenses	74,289	69,066
Operating profit (loss)	42,340	35,583
Investments In New Businesses
Segment Reporting Information [Line Items]
Revenues	3,388	3,038
Expenses	10,910	5,940
Operating profit (loss)	$ (7,522)	$ (2,902)