Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 744.0	$ 659.6	$ 2,199.5	$ 1,939.2
Freight Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	704.5	628.0	2,089.1	1,830.9
Chemical and Petroleum [Member]
Disaggregation of Revenue [Line Items]
Revenues	204.1	191.9	667.9	549.0
Chemicals [Member]
Disaggregation of Revenue [Line Items]
Revenues	71.0	60.1	196.4	174.8
Petroleum [Member]
Disaggregation of Revenue [Line Items]
Revenues	93.7	95.1	361.8	261.5
Plastics [Member]
Disaggregation of Revenue [Line Items]
Revenues	39.4	36.7	109.7	112.7
Industrial and Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	159.0	126.4	437.6	406.0
Forest Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	71.6	59.6	191.9	186.3
Metals and Scrap [Member]
Disaggregation of Revenue [Line Items]
Revenues	54.1	41.5	151.4	144.2
Other Industrial and Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	33.3	25.3	94.3	75.5
Agriculture and Minerals [Member]
Disaggregation of Revenue [Line Items]
Revenues	139.8	125.3	404.1	374.2
Grain [Member]
Disaggregation of Revenue [Line Items]
Revenues	87.0	74.6	250.6	216.5
Food Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	35.4	38.2	109.0	119.9
Ores and Minerals [Member]
Disaggregation of Revenue [Line Items]
Revenues	7.5	5.5	18.8	16.6
Stone, Clay and Glass [Member]
Disaggregation of Revenue [Line Items]
Revenues	9.9	7.0	25.7	21.2
Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues	74.6	46.8	186.6	142.4
Utility Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues	45.8	28.9	108.7	75.7
Coal and Petroleum Coke [Member]
Disaggregation of Revenue [Line Items]
Revenues	12.8	10.2	35.2	31.3
Frac Sand [Member]
Disaggregation of Revenue [Line Items]
Revenues	4.0	2.3	11.6	7.8
Crude Oil [Member]
Disaggregation of Revenue [Line Items]
Revenues	12.0	5.4	31.1	27.6
Intermodal [Member]
Disaggregation of Revenue [Line Items]
Revenues	86.9	89.1	259.3	241.3
Automotive [Member]
Disaggregation of Revenue [Line Items]
Revenues	40.1	48.5	133.6	118.0
Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 39.5	$ 31.6	$ 110.4	$ 108.3