Equity (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		9 Months Ended
	Aug. 07, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 3,232.4	$ 2,853.4	$ 3,058.7	$ 2,713.7
Net income		90.7	100.1	286.9	235.9
Other comprehensive income (loss)		0.2	(1.0)	(0.1)	(0.5)
Contribution from noncontrolling interest				0	2.0
Conversion of series D cumulative convertible preferred stock				0	(0.2)
Common stock issued for conversion of series D cumulative convertible preferred stock				0	0.2
Dividends on common stock	(21.5)	(21.5)	0	(64.4)	0
Options exercised and stock subscribed, net of shares withheld for employee taxes		0.8	1.3	1.8	0.3
Tax benefit from share-based compensation		8.1	0	22.2	0
Share-based compensation		2.6	1.1	8.3	6.4
Ending balance		3,313.2	2,954.9	3,313.2	2,954.9
$25 Par Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock		(0.1)	0	(0.2)	(0.2)
Series D [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock				0	(2.7)
Kansas City Southern Stockholders' Equity [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		2,937.4	2,567.8	2,764.5	2,431.1
Net income		90.1	99.8	285.5	234.6
Other comprehensive income (loss)		0.2	(1.0)	(0.1)	(0.5)
Contribution from noncontrolling interest				0	0
Conversion of series D cumulative convertible preferred stock				0	(0.2)
Common stock issued for conversion of series D cumulative convertible preferred stock				0	0.2
Dividends on common stock		(21.5)	0	(64.4)	0
Options exercised and stock subscribed, net of shares withheld for employee taxes		0.8	1.3	1.8	0.3
Tax benefit from share-based compensation		8.1	0	22.2	0
Share-based compensation		2.6	1.1	8.3	6.4
Ending balance		3,017.6	2,669.0	3,017.6	2,669.0
Kansas City Southern Stockholders' Equity [Member] | $25 Par Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock		(0.1)	0	(0.2)	(0.2)
Kansas City Southern Stockholders' Equity [Member] | Series D [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock				0	(2.7)
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		295.0	285.6	294.2	282.6
Net income		0.6	0.3	1.4	1.3
Contribution from noncontrolling interest				0	2.0
Ending balance		$ 295.6	$ 285.9	$ 295.6	$ 285.9