Statements Of Consolidated Operations - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Operating Revenue	$ 5,092.0	$ 4,891.0	$ 4,697.5
Operating Expenses:
Salaries, wages and employee benefits	2,950.0	2,884.2	2,802.9
Fuel, operating expenses and supplies	940.2	867.5	799.1
Purchased transportation	683.2	627.5	553.6
Depreciation and amortization	147.7	147.7	159.8
Other operating expenses	248.8	245.7	252.2
Gains on property disposals, net	(20.8)	(0.6)	(14.6)
Total operating expenses	4,949.1	4,772.0	4,553.0
Operating Income	142.9	119.0	144.5
Nonoperating Expenses:
Interest expense	105.8	102.8	103.4
Non-union pension and postretirement benefits	9.4	20.6	20.2
Other, net	(3.6)	13.7	(3.7)
Nonoperating expenses, net	111.6	137.1	119.9
Income (Loss) before income taxes	31.3	(18.1)	24.6
Income tax expense (benefit)	11.1	(7.3)	3.1
Net Income (Loss)	20.2	(10.8)	21.5
Net Income (Loss) Attributable to Common Shareholders	$ 20.2	$ (10.8)	$ 21.5
Average Common Shares Outstanding - Basic (in shares)	32,983	32,685	32,416
Dilutive weighted average shares outstanding (in shares)	33,859	32,685	33,040
Earnings (Loss) Per Share - Basic (in dollars per share)	$ 0.61	$ (0.33)	$ 0.66
Earnings (Loss) Per Share - Diluted (in dollars per share)	$ 0.60	$ (0.33)	$ 0.65