Significant Accounting Policies - Estimated Useful Lives Of Property And Equipment (Details)	12 Months Ended
	Dec. 31, 2021
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset	Lesser of economic life or life of lease
Minimum [Member] | Structures [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	7 years
Minimum [Member] | Revenue Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	4 years
Minimum [Member] | Other Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	2 years
Maximum [Member] | Structures [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	30 years
Maximum [Member] | Revenue Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	15 years
Maximum [Member] | Other Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of asset, years	20 years