Condensed Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2021		$ 156.8	$ 1,969.6	$ (488.0)	$ 1,013.8
Common stock repurchased and retired	$ (1,100.6)	(20.8)	(1,079.8)
Stock Issued During Period, Value, Stock Options Exercised	21.3	0.9	20.4
Common stock issued for other transactions		0.1	3.1
Stock-based compensation			7.0
Other comprehensive income (loss)	(74.3)			(74.3)
Net income	1,130.3				1,130.3
Common stock dividends paid					(89.4)
Balance at end of period at Sep. 30, 2022	2,549.7	$ 137.0	920.3	(562.3)	2,054.7
Balance at beginning of period at Dec. 31, 2021						$ 0.0
Net income (loss) attributable to noncontrolling interests	0.0					0.0
Contributions received from noncontrolling interests	0.0					0.0
Balance at end of period at Sep. 30, 2022	0.0					0.0
Dividends declared per share of common stock		$ 0.60
Balance at beginning of period at Jun. 30, 2022		$ 145.1	1,318.5	(535.5)	1,768.0
Common stock repurchased and retired		(8.2)	(402.7)
Stock Issued During Period, Value, Stock Options Exercised		0.0	0.4
Common stock issued for other transactions		0.1	0.1
Stock-based compensation			4.0
Other comprehensive income (loss)	(26.8)			(26.8)
Net income	315.2				315.2
Common stock dividends paid					(28.5)
Balance at end of period at Sep. 30, 2022	2,549.7	$ 137.0	920.3	(562.3)	2,054.7
Balance at beginning of period at Jun. 30, 2022						0.0
Net income (loss) attributable to noncontrolling interests	0.0					0.0
Contributions received from noncontrolling interests						0.0
Balance at end of period at Sep. 30, 2022	0.0					0.0
Dividends declared per share of common stock		$ 0.20
Total equity	2,549.7
Total equity	2,543.6
Balance at beginning of period at Dec. 31, 2022	2,543.6	$ 132.3	682.7	(495.9)	2,224.5
Common stock repurchased and retired	(595.1)	(10.8)	(584.3)
Stock Issued During Period, Value, Stock Options Exercised	22.3	0.8	21.5
Common stock issued for other transactions		0.2	1.6
Stock-based compensation			8.6
Other comprehensive income (loss)	15.6			15.6
Net income	403.2				407.3
Common stock dividends paid					(76.6)
Balance at end of period at Sep. 30, 2023	2,327.5	$ 122.5	130.1	(480.3)	2,555.2
Balance at beginning of period at Dec. 31, 2022	0.0					0.0
Net income (loss) attributable to noncontrolling interests	(4.1)					(4.1)
Contributions received from noncontrolling interests	44.1					44.1
Balance at end of period at Sep. 30, 2023	40.0					40.0
Dividends declared per share of common stock		$ 0.60
Balance at beginning of period at Jun. 30, 2023		$ 125.8	313.7	(483.4)	2,475.9
Common stock repurchased and retired		(3.7)	(198.3)
Stock Issued During Period, Value, Stock Options Exercised		0.4	9.9
Common stock issued for other transactions		0.0	0.1
Stock-based compensation			4.7
Other comprehensive income (loss)	3.1			3.1
Net income	104.5				104.1
Common stock dividends paid					(24.8)
Balance at end of period at Sep. 30, 2023	2,327.5	$ 122.5	$ 130.1	$ (480.3)	$ 2,555.2
Balance at beginning of period at Jun. 30, 2023						39.6
Net income (loss) attributable to noncontrolling interests	0.4					0.4
Contributions received from noncontrolling interests						0.0
Balance at end of period at Sep. 30, 2023	40.0					$ 40.0
Dividends declared per share of common stock		$ 0.20
Total equity	$ 2,367.5