Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.21.2
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Accounting Policies [Abstract]        
Contract cost, amortization period 1 year   1 year  
Fuel revenue and fuel costs included fuel taxes $ 262.7 $ 102.0 $ 485.2 $ 217.1