Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	$ 2,632.6	$ 2,866.0	$ 2,714.0
Operating expenses:
Compensation and benefits	476.5	529.1	495.7
Purchased services	198.1	219.2	200.7
Fuel	219.8	340.4	348.2
Mexican fuel excise tax credit	0.0	0.0	(37.7)
Equipment costs	85.8	108.6	126.1
Depreciation and amortization	357.9	350.7	346.7
Materials and other	260.9	262.9	265.9
Write-off of software development costs	13.6	0.0	0.0
Restructuring charges	17.0	168.8	0.0
Gain on insurance recoveries related to hurricane damage	0.0	0.0	(17.9)
Total operating expenses	1,629.6	1,979.7	1,727.7
Operating income	1,003.0	886.3	986.3
Equity in net earnings (losses) of affiliates	(1.4)	1.0	2.6
Interest expense	(150.9)	(115.9)	(110.0)
Debt retirement costs	0.0	(1.1)	(2.2)
Foreign exchange gain (loss)	(29.6)	17.1	7.8
Other income, net	2.1	1.0	2.4
Income before income taxes	823.2	788.4	886.9
Income tax expense	204.1	247.6	257.5
Net income	619.1	540.8	629.4
Less: Net income attributable to noncontrolling interest	2.1	1.9	2.0
Net income attributable to Kansas City Southern and subsidiaries	617.0	538.9	627.4
Preferred stock dividends	0.2	0.2	0.2
Net income available to common stockholders	$ 616.8	$ 538.7	$ 627.2
Earnings per share:
Basic earnings per share	$ 6.57	$ 5.42	$ 6.16
Diluted earnings per share	$ 6.54	$ 5.40	$ 6.13
Average shares outstanding (in thousands):
Basic	93,826	99,316	101,852
Effect of dilution	489	431	418
Diluted	94,315	99,747	102,270