Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies (Disaggregated Revenue) (Details)

v3.10.0.1
Significant Accounting Policies (Disaggregated Revenue) (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disaggregation of Revenue [Line Items]                      
Revenue from operations $ 1,026,944 $ 1,058,233 $ 1,033,498 $ 925,020 $ 891,117 $ 872,987 $ 839,912 $ 754,096 $ 4,043,695 $ 3,358,112 $ 2,991,517
LTL Service Revenue [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from operations                 3,982,658 3,303,611 2,939,572
Other Service Revenue [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from operations                 $ 61,037 $ 54,501 $ 51,945