Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 693.4	$ 659.6	$ 547.9	$ 731.7	$ 729.5	$ 747.7	$ 714.0	$ 674.8	$ 2,632.6	$ 2,866.0	$ 2,714.0
Freight Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues									2,493.7	2,725.9	2,591.8
Chemical and Petroleum [Member]
Disaggregation of Revenue [Line Items]
Revenues									763.8	737.2	622.1
Chemicals [Member]
Disaggregation of Revenue [Line Items]
Revenues									236.7	246.9	236.3
Petroleum [Member]
Disaggregation of Revenue [Line Items]
Revenues									375.0	341.8	241.9
Plastics [Member]
Disaggregation of Revenue [Line Items]
Revenues									152.1	148.5	143.9
Industrial and Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenues									537.7	610.4	591.0
Forest Products [Member]
Disaggregation of Revenue [Line Items]
Revenues									247.8	261.4	268.0
Metals and Scrap [Member]
Disaggregation of Revenue [Line Items]
Revenues									188.4	232.9	208.2
Other Industrial and Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenues									101.5	116.1	114.8
Agriculture and Minerals [Member]
Disaggregation of Revenue [Line Items]
Revenues									505.4	506.3	486.4
Grain [Member]
Disaggregation of Revenue [Line Items]
Revenues									299.6	298.4	289.9
Food Products [Member]
Disaggregation of Revenue [Line Items]
Revenues									154.6	149.4	145.7
Ores and Minerals [Member]
Disaggregation of Revenue [Line Items]
Revenues									21.8	25.0	20.9
Stone, Clay and Glass [Member]
Disaggregation of Revenue [Line Items]
Revenues									29.4	33.5	29.9
Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues									195.0	246.2	256.3
Utility Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues									105.6	126.9	117.3
Coal and Petroleum Coke [Member]
Disaggregation of Revenue [Line Items]
Revenues									41.8	43.2	44.3
Frac Sand [Member]
Disaggregation of Revenue [Line Items]
Revenues									11.3	27.4	37.4
Crude Oil [Member]
Disaggregation of Revenue [Line Items]
Revenues									36.3	48.7	57.3
Intermodal [Member]
Disaggregation of Revenue [Line Items]
Revenues									319.1	370.2	382.8
Automotive [Member]
Disaggregation of Revenue [Line Items]
Revenues									172.7	255.6	253.2
Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues									$ 138.9	$ 140.1	$ 122.2