Condensed Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Statements of Comprehensive Income [Line Items]
Revenues	$ 656.6	$ 604.5	$ 1,922.5	$ 1,735.7
Operating expenses	422.8	404.7	1,238.7	1,128.1
Operating income	233.8	199.8	683.8	607.6
Equity in net earnings (losses) of affiliates	2.8	3.5	9.7	10.4
Interest expense	(25.2)	(25.2)	(74.9)	(73.2)
Foreign exchange gain (loss)	0.8	(19.8)	61.8	(47.3)
Other income (expense), net	(0.3)	0.0	0.7	(0.5)
Income before income taxes	211.9	158.3	681.1	497.0
Income tax expense	82.0	37.3	269.6	147.4
Net income	129.9	121.0	411.5	349.6
Less: Net income attributable to noncontrolling interest	0.6	0.4	1.2	1.1
Net income attributable to Kansas City Southern and subsidiaries	129.3	120.6	410.3	348.5
Other comprehensive income (loss)	(0.7)	(0.3)	(1.7)	(1.0)
Comprehensive income attributable to Kansas City Southern and subsidiaries	128.6	120.3	408.6	347.5
Condensed Consolidating Financial Information KCS [Member] | Consolidating Adjustments [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	(4.4)	(4.4)	(13.1)	(13.4)
Operating expenses	(4.4)	(4.4)	(13.1)	(13.4)
Operating income	0.0	0.0	0.0	0.0
Equity in net earnings (losses) of affiliates	(132.1)	(120.3)	(414.6)	(339.6)
Interest expense	21.6	33.8	67.8	97.7
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	(21.5)	(33.3)	(67.8)	(96.5)
Income before income taxes	(132.0)	(119.8)	(414.6)	(338.4)
Income tax expense	0.0	0.0	0.0	0.0
Net income	(132.0)	(119.8)	(414.6)	(338.4)
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	(132.0)	(119.8)	(414.6)	(338.4)
Other comprehensive income (loss)	0.3	0.4	(1.8)	1.7
Comprehensive income attributable to Kansas City Southern and subsidiaries	(131.7)	(119.4)	(416.4)	(336.7)
Condensed Consolidating Financial Information KCS [Member] | Parent [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	0.0	0.0	0.0	0.0
Operating expenses	0.8	0.9	4.9	3.7
Operating income	(0.8)	(0.9)	(4.9)	(3.7)
Equity in net earnings (losses) of affiliates	130.2	119.1	410.8	336.3
Interest expense	(20.3)	(21.7)	(61.0)	(61.1)
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	20.8	26.3	66.7	79.1
Income before income taxes	129.9	122.8	411.6	350.6
Income tax expense	0.6	2.2	1.3	2.1
Net income	129.3	120.6	410.3	348.5
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	129.3	120.6	410.3	348.5
Other comprehensive income (loss)	(0.7)	(0.3)	(1.7)	(1.0)
Comprehensive income attributable to Kansas City Southern and subsidiaries	128.6	120.3	408.6	347.5
Condensed Consolidating Financial Information KCS [Member] | Guarantor Subsidiaries [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	316.1	289.9	924.4	817.5
Operating expenses	221.6	214.7	661.4	585.1
Operating income	94.5	75.2	263.0	232.4
Equity in net earnings (losses) of affiliates	2.5	1.7	5.3	4.7
Interest expense	(17.7)	(20.6)	(54.6)	(63.2)
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	(0.3)	(0.1)	0.5	0.0
Income before income taxes	79.0	56.2	214.2	173.9
Income tax expense	26.4	19.9	78.1	65.9
Net income	52.6	36.3	136.1	108.0
Less: Net income attributable to noncontrolling interest	0.6	0.4	1.2	1.1
Net income attributable to Kansas City Southern and subsidiaries	52.0	35.9	134.9	106.9
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income attributable to Kansas City Southern and subsidiaries	52.0	35.9	134.9	106.9
Condensed Consolidating Financial Information KCS [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	344.9	319.0	1,011.2	931.6
Operating expenses	204.8	193.5	585.5	552.7
Operating income	140.1	125.5	425.7	378.9
Equity in net earnings (losses) of affiliates	2.2	3.0	8.2	9.0
Interest expense	(8.8)	(16.7)	(27.1)	(46.6)
Foreign exchange gain (loss)	0.8	(19.8)	61.8	(47.3)
Other income (expense), net	0.7	7.1	1.3	16.9
Income before income taxes	135.0	99.1	469.9	310.9
Income tax expense	55.0	15.2	190.2	79.4
Net income	80.0	83.9	279.7	231.5
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	80.0	83.9	279.7	231.5
Other comprehensive income (loss)	(0.3)	(0.4)	1.8	(1.7)
Comprehensive income attributable to Kansas City Southern and subsidiaries	79.7	83.5	281.5	229.8
Condensed Consolidating Financial Information KCSR [Member] | Consolidating Adjustments [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	(8.9)	(9.8)	(28.1)	(28.6)
Operating expenses	(8.9)	(9.8)	(28.1)	(28.6)
Operating income	0.0	0.0	0.0	0.0
Equity in net earnings (losses) of affiliates	(131.4)	(119.5)	(412.6)	(338.2)
Interest expense	21.6	33.8	67.8	97.7
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	(21.5)	(33.3)	(67.8)	(96.5)
Income before income taxes	(131.3)	(119.0)	(412.6)	(337.0)
Income tax expense	0.0	0.0	0.0	0.0
Net income	(131.3)	(119.0)	(412.6)	(337.0)
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	(131.3)	(119.0)	(412.6)	(337.0)
Other comprehensive income (loss)	0.3	0.4	(1.8)	1.7
Comprehensive income attributable to Kansas City Southern and subsidiaries	(131.0)	(118.6)	(414.4)	(335.3)
Condensed Consolidating Financial Information KCSR [Member] | Parent [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	0.0	0.0	0.0	0.0
Operating expenses	0.8	0.9	4.9	3.7
Operating income	(0.8)	(0.9)	(4.9)	(3.7)
Equity in net earnings (losses) of affiliates	130.2	119.1	410.8	336.3
Interest expense	(20.3)	(21.7)	(61.0)	(61.1)
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	20.8	26.3	66.7	79.1
Income before income taxes	129.9	122.8	411.6	350.6
Income tax expense	0.6	2.2	1.3	2.1
Net income	129.3	120.6	410.3	348.5
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	129.3	120.6	410.3	348.5
Other comprehensive income (loss)	(0.7)	(0.3)	(1.7)	(1.0)
Comprehensive income attributable to Kansas City Southern and subsidiaries	128.6	120.3	408.6	347.5
Condensed Consolidating Financial Information KCSR [Member] | KCSR [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	310.7	283.5	906.4	798.8
Operating expenses	216.5	210.1	647.0	571.6
Operating income	94.2	73.4	259.4	227.2
Equity in net earnings (losses) of affiliates	(0.3)	(0.3)	(0.6)	0.0
Interest expense	(17.7)	(20.6)	(54.6)	(63.2)
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	(0.3)	(0.1)	0.5	0.0
Income before income taxes	75.9	52.4	204.7	164.0
Income tax expense	25.4	18.8	75.2	62.4
Net income	50.5	33.6	129.5	101.6
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	50.5	33.6	129.5	101.6
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income attributable to Kansas City Southern and subsidiaries	50.5	33.6	129.5	101.6
Condensed Consolidating Financial Information KCSR [Member] | Guarantor Subsidiaries [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	9.9	11.8	33.0	33.9
Operating expenses	9.6	10.0	29.4	28.7
Operating income	0.3	1.8	3.6	5.2
Equity in net earnings (losses) of affiliates	2.1	1.2	3.9	3.3
Interest expense	0.0	0.0	0.0	0.0
Foreign exchange gain (loss)	0.0	0.0	0.0	0.0
Other income (expense), net	0.0	0.0	0.0	0.0
Income before income taxes	2.4	3.0	7.5	8.5
Income tax expense	1.0	1.1	2.9	3.5
Net income	1.4	1.9	4.6	5.0
Less: Net income attributable to noncontrolling interest	0.6	0.4	1.2	1.1
Net income attributable to Kansas City Southern and subsidiaries	0.8	1.5	3.4	3.9
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income attributable to Kansas City Southern and subsidiaries	0.8	1.5	3.4	3.9
Condensed Consolidating Financial Information KCSR [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Statements of Comprehensive Income [Line Items]
Revenues	344.9	319.0	1,011.2	931.6
Operating expenses	204.8	193.5	585.5	552.7
Operating income	140.1	125.5	425.7	378.9
Equity in net earnings (losses) of affiliates	2.2	3.0	8.2	9.0
Interest expense	(8.8)	(16.7)	(27.1)	(46.6)
Foreign exchange gain (loss)	0.8	(19.8)	61.8	(47.3)
Other income (expense), net	0.7	7.1	1.3	16.9
Income before income taxes	135.0	99.1	469.9	310.9
Income tax expense	55.0	15.2	190.2	79.4
Net income	80.0	83.9	279.7	231.5
Less: Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Kansas City Southern and subsidiaries	80.0	83.9	279.7	231.5
Other comprehensive income (loss)	(0.3)	(0.4)	1.8	(1.7)
Comprehensive income attributable to Kansas City Southern and subsidiaries	$ 79.7	$ 83.5	$ 281.5	$ 229.8