Investments in Securities and Fair Value Investments in Securities (Schedule of Variable Interest Entities) (Details) - Other Investments $ in Thousands	Dec. 31, 2023 USD ($)
Variable Interest Entity [Line Items]
Variable Interest Entity Nonconsolidated Carrying Amount	$ 13,510
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	14,366
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	18,140
Real estate LLCs or LPs
Variable Interest Entity [Line Items]
Variable Interest Entity Nonconsolidated Carrying Amount	13,310
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	14,166
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	18,060
Small business investment LLCs or LPs
Variable Interest Entity [Line Items]
Variable Interest Entity Nonconsolidated Carrying Amount	200
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	200
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	$ 80