Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 156.5	$ 190.2	$ (68.1)	$ 452.8
Other comprehensive income (loss):
Unrealized gain (loss) on interest rate derivative instruments, net of tax of $(0.4) million, $0.7 million, $11.6 million and $3.4 million, respectively	(1.7)	2.6	43.5	12.7
Reclassification adjustment from cash flow hedges included in net income, net of tax of $0.1 million, $0.1 million, $0.3 million and $0.4 million, respectively	0.5	0.6	1.5	1.5
Foreign currency translation adjustments	(0.2)	0.1	(0.1)	(1.4)
Other comprehensive income (loss)	(1.4)	3.3	44.9	12.8
Comprehensive income (loss)	155.1	193.5	(23.2)	465.6
Less: Comprehensive income attributable to noncontrolling interest	0.3	0.4	1.2	1.5
Comprehensive income (loss) attributable to Kansas City Southern and subsidiaries	$ 154.8	$ 193.1	$ (24.4)	$ 464.1