Statements Of Consolidated Operations - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Operating Revenue	$ 4,697.5	$ 4,832.4	$ 5,068.8
Operating Expenses:
Salaries, wages and employee benefits	2,823.1	2,868.2	2,901.2
Operating expenses and supplies	799.1	878.4	1,110.7
Purchased transportation	553.6	561.1	590.9
Depreciation and amortization	159.8	163.7	163.6
Other operating expenses	252.2	266.1	268.8
(Gains) losses on property disposals, net	(14.6)	1.9	(11.9)
Total operating expenses	4,573.2	4,739.4	5,023.3
Operating Income	124.3	93.0	45.5
Nonoperating Expenses:
Interest expense	103.4	107.6	150.0
(Gain) loss on extinguishment of debt	0.0	0.6	(11.2)
Other, net	(3.7)	(10.8)	(9.5)
Nonoperating expenses, net	99.7	97.4	129.3
Income (Loss) before income taxes	24.6	(4.4)	(83.8)
Income tax expense (benefit)	3.1	(5.1)	(16.1)
Net Income (Loss)	21.5	0.7	(67.7)
Amortization of beneficial conversion feature on preferred stock	0.0	0.0	(18.1)
Net Income (Loss) Attributable to Common Shareholders	$ 21.5	$ 0.7	$ (85.8)
Average Common Shares Outstanding - Basic	32,416	31,736	28,592
Average Common Shares Outstanding - Diluted	33,040	32,592	28,592
Earnings (Loss) Per Share - Basic (in dollars per share)	$ 0.66	$ 0.02	$ (3.00)
Earnings (Loss) Per Share - Diluted (in dollars per share)	$ 0.65	$ 0.02	$ (3.00)