Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Revenue:
Total Operating Revenue	$ 2,203.1	$ 2,222.8	$ 2,046.9
Costs and Expenses:
Operating costs	(1,878.0)	(1,875.0)	(1,721.0)
Income from SSAT	20.8	36.8	28.2
Selling, general and administrative	(216.8)	(220.8)	(206.8)
Total Costs and Expenses	(2,074.0)	(2,059.0)	(1,899.6)
Operating Income	129.1	163.8	147.3
Interest expense	(22.5)	(18.7)	(24.2)
Other income (expense), net	1.2	2.6	2.1
Income before Income Taxes	107.8	147.7	125.2
Income taxes	(25.1)	(38.7)	105.8
Net Income	82.7	109.0	231.0
Other Comprehensive Income (Loss), Net of Income Taxes:
Net Income	82.7	109.0	231.0
Other Comprehensive Income (Loss):
Net gain in prior service cost			0.8
Amortization of prior service cost	(4.5)	(4.7)	(4.0)
Amortization of net loss (gain)	2.7	1.1	1.7
Other adjustments	(0.6)		0.2
Total Other Comprehensive (Loss) Income	(2.4)	(3.6)	(1.3)
Comprehensive Income	$ 80.3	$ 105.4	$ 229.7
Basic Earnings Per-Share: (in dollars per share)	$ 1.93	$ 2.55	$ 5.38
Diluted Earnings Per-Share: (in dollars per share)	$ 1.91	$ 2.53	$ 5.35
Weighted Average Number of Shares Outstanding:
Basic (in shares)	42.8	42.7	42.9
Diluted (in shares)	43.3	43.0	43.2
Ocean Transportation
Operating Revenue:
Total Operating Revenue	$ 1,666.6	$ 1,641.3	$ 1,571.8
Logistics
Operating Revenue:
Total Operating Revenue	$ 536.5	$ 581.5	$ 475.1