Significant Accounting Policies - Disaggregated Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from operations	$ 5,256,328	$ 4,015,129	$ 4,109,111
LTL Service Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from operations	5,177,497	3,961,054	4,055,467
Other Service Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from operations	$ 78,831	$ 54,075	$ 53,644