Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Impairment recognized	$ 0	$ 0
Goodwill	178,800,000	178,800,000	$ 178,800,000	$ 178,800,000
Intangible assets	$ 15,500,000	$ 15,500,000	15,500,000	15,500,000
Impairments related to an intangible asset with an indefinite life			$ 0	$ 500,000
Impairment, Intangible Asset, Indefinite-Lived (Excluding Goodwill), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other than Temporary Impairment Losses, Investments	Other than Temporary Impairment Losses, Investments
U.S. statutory income tax rate			21.00%	21.00%
Accounting Standards Update [Extensible Enumeration]			Accounting Standards Update 2018-12 [Member]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2023		Jan. 01, 2023
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, immaterial effect	true		true
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	3 years		3 years
Minimum [Member] | Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	5 years		5 years
Minimum [Member] | Real Estate And Fleet Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	4 years		4 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	30 years		30 years
Maximum [Member] | Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	7 years		7 years
Maximum [Member] | Real Estate And Fleet Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, equipment and leasehold improvements, estimated useful lives	6 years		6 years