Condensed Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating Revenue:
Total Operating Revenue	$ 1,261.1	$ 874.9	$ 2,426.6	$ 1,586.7
Costs and Expenses:
Operating costs	(728.4)	(615.6)	(1,432.1)	(1,160.3)
Income from SSAT	24.7	12.8	58.7	22.0
Selling, general and administrative	(64.3)	(58.2)	(127.5)	(114.3)
Total Costs and Expenses	(768.0)	(661.0)	(1,500.9)	(1,252.6)
Operating Income	493.1	213.9	925.7	334.1
Interest expense	(4.5)	(5.5)	(9.3)	(12.8)
Other income (expense), net	1.8	1.5	3.8	2.9
Income before Taxes	490.4	209.9	920.2	324.2
Income taxes	(109.7)	(47.4)	(200.3)	(74.5)
Net Income	380.7	162.5	719.9	249.7
Other Comprehensive Income (Loss), Net of Income Taxes:
Net Income	380.7	162.5	719.9	249.7
Other Comprehensive Income (Loss):
Amortization of prior service cost	(0.9)	(1.2)	(1.8)	(2.3)
Amortization of net loss (gain)	2.0	1.3	2.8	2.5
Other adjustments	(1.9)	0.1	(1.6)	(0.1)
Total Other Comprehensive Income (Loss)	(0.8)	0.2	(0.6)	0.1
Comprehensive Income	$ 379.9	$ 162.7	$ 719.3	$ 249.8
Basic Earnings Per Share (in dollars per share)	$ 9.54	$ 3.74	$ 17.82	$ 5.75
Diluted Earnings Per Share (in dollars per share)	$ 9.49	$ 3.71	$ 17.69	$ 5.70
Weighted Average Number of Shares Outstanding:
Basic (in shares)	39.9	43.5	40.4	43.4
Diluted (in shares)	40.1	43.8	40.7	43.8
Ocean. Transportation.
Operating Revenue:
Total Operating Revenue	$ 1,049.2	$ 682.9	$ 1,993.1	$ 1,243.4
Logistics.
Operating Revenue:
Total Operating Revenue	$ 211.9	$ 192.0	$ 433.5	$ 343.3