CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenue	$ 1,454.1	$ 1,737.0	$ 1,613.1
Operating expenses:
Salaries, wages and employee benefits	399.4	483.2	407.4
Operations and maintenance	169.1	213.1	181.5
Communications	3.6	4.4	3.3
Administrative expenses	66.5	75.5	58.5
Sales and marketing	1.8	5.1	3.4
Insurance and claims	66.9	49.9	45.8
Acquisition-related transaction expenses			2.6
Depreciation and amortization	98.3	146.5	131.1
Gain on disposition of revenue property and equipment	(6.9)	(5.2)	(3.2)
Impairment	15.4	312.8	13.9
Restructuring charges	9.5	8.4
Total operating expenses	1,418.7	2,049.1	1,591.2
Income (loss) from operations	35.4	(312.1)	21.9
Other expense (income):
Interest income	(0.6)	(1.0)	(1.3)
Interest expense	44.9	50.4	45.5
Write-off of deferred financing fees		2.3
Other	(14.9)	(1.8)	(1.2)
Total other expense	29.4	49.9	43.0
Income (loss) before benefit for income taxes	6.0	(362.0)	(21.1)
Income tax benefit	(0.2)	(54.6)	(15.9)
Net income (loss)	6.2	(307.4)	(5.2)
Other comprehensive income:
Foreign currency translation adjustments, net of tax expense (benefit) of $0.0, $0.3 and $(0.5), respectively	0.4	0.5	(1.8)
Comprehensive income (loss)	6.6	(306.9)	(7.0)
Net income (loss)	6.2	(307.4)	(5.2)
Net income (loss) attributable to common stockholders	$ 1.3	$ (312.4)	$ (10.1)
Earnings (loss) per common share:
Basic (in dollars per share)	$ 0.02	$ (4.86)	$ (0.16)
Diluted (in dollars per share)	$ 0.02	$ (4.86)	$ (0.16)
Weighted-average common shares outstanding:
Basic (in shares)	64,775,275	64,303,438	61,654,820
Diluted (in shares)	65,671,246	64,303,438	61,654,820
Series A
Other comprehensive income:
Less dividends to convertible preferred stockholders	$ (4.9)	$ (5.0)	$ (4.9)
Weighted-average common shares outstanding:
Dividends declared per convertible preferred share	$ 7.63	$ 7.63	$ 7.63
Company freight
Revenues:
Total revenue	$ 676.8	$ 804.6	$ 721.7
Operating expenses:
Purchased freight	491.4	597.7	588.6
Owner operator freight
Revenues:
Total revenue	408.9	455.3	440.5
Brokerage
Revenues:
Total revenue	234.3	294.7	266.4
Logistics
Revenues:
Total revenue	37.4	47.5	42.8
Fuel surcharge
Revenues:
Total revenue	96.7	134.9	141.7
Operating expenses:
Fuel	87.3	138.5	141.1
Service
Operating expenses:
Taxes and licenses	$ 16.4	$ 19.2	$ 17.2