Equity (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended
	May 02, 2012	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 3,130.2	$ 2,778.6	$ 3,058.7	$ 2,713.7
Net income		120.9	71.7	196.2	135.8
Other comprehensive income (loss)		(0.6)	0	(0.3)	0.5
Contribution from noncontrolling interest		0	2.0	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	(42.9)	0
Options exercised and stock subscribed, net of shares withheld for employee taxes		0	(0.1)	1.0	(1.0)
Tax benefit from share-based compensation		0.9	0	14.1	0
Share-based compensation		2.5	1.3	5.7	5.3
Ending balance		3,232.4	2,853.4	3,232.4	2,853.4
$25 Par Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock		0	(0.1)	(0.1)	(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		2,835.7	2,495.9	2,764.5	2,431.1
Net income		120.4	70.8	195.4	134.8
Other comprehensive income (loss)		(0.6)	0	(0.3)	0.5
Contribution from noncontrolling interest		0	0	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	(42.9)	0
Options exercised and stock subscribed, net of shares withheld for employee taxes		0	(0.1)	1.0	(1.0)
Tax benefit from share-based compensation		0.9	0	14.1	0
Share-based compensation		2.5	1.3	5.7	5.3
Ending balance		2,937.4	2,567.8	2,937.4	2,567.8
Kansas City Southern Stockholders' Equity [Member] | $25 Par Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on preferred stock		0	(0.1)	(0.1)	(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		294.5	282.7	294.2	282.6
Net income		0.5	0.9	0.8	1.0
Other comprehensive income (loss)		0	0	0	0
Contribution from noncontrolling interest		0	2.0	0	2.0
Conversion of series D cumulative convertible preferred stock				0	0
Common stock issued for conversion of series D cumulative convertible preferred stock				0	0
Dividends on common stock		0	0	0	0
Options exercised and stock subscribed, net of shares withheld for employee taxes		0	0	0	0
Tax benefit from share-based compensation		0	0	0	0
Share-based compensation		0	0	0	0
Ending balance		$ 295.0	$ 285.6	$ 295.0	$ 285.6