CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Common Stock	Common Stock and Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests	Total
Balance at Dec. 31, 2020		$ 0.1	$ 5,193.2	$ (77.9)	$ 7.3	$ 5,122.7
Balance (in shares) at Dec. 31, 2020	63,600,000
Increase (Decrease) in Stockholders' Equity
Net income			266.9		1.3	268.2
Other comprehensive loss				(1.2)		(1.2)
Dividend to noncontrolling interest holder					(2.4)	(2.4)
Stock-based compensation		14.7				14.7
Stock-based compensation (in shares)	107,000
Common stock withheld related to net share settlements		(8.2)				$ (8.2)
Repurchase of common shares (in shares)						0
Cash dividends per share and dividend equivalents			(44.8)			$ (44.8)
Balance at Mar. 31, 2021		6.6	5,415.3	(79.1)	6.2	5,349.0
Balance (in shares) at Mar. 31, 2021	63,707,000
Balance at Dec. 31, 2021		0.1	6,155.3	(68.9)	7.2	$ 6,093.7
Balance (in shares) at Dec. 31, 2021	61,806,000					61,806,000
Increase (Decrease) in Stockholders' Equity
Net income			523.3		1.3	$ 524.6
Other comprehensive loss				0.6		0.6
Dividend to noncontrolling interest holder					(1.1)	(1.1)
Stock-based compensation		11.8				11.8
Stock-based compensation (in shares)	255,000
Common stock withheld related to net share settlements		(17.1)				(17.1)
Repurchase of common shares		5.3	(22.4)			$ (17.1)
Repurchase of common shares (in shares)	(113,000)					113,529
Cash dividends per share and dividend equivalents			(56.7)			$ (56.7)
Balance at Mar. 31, 2022		$ 0.1	$ 6,599.5	$ (68.3)	$ 7.4	$ 6,538.7
Balance (in shares) at Mar. 31, 2022	61,948,000					61,948,000