Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss
Balance at beginning of period at Dec. 31, 2020		$ 5.7	$ 59.1	$ 2,689.6	$ (21.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised			24.4
Purchases of common stock			0.0	0.0
Stock-based compensation			4.3
Net earnings	$ 693.8			693.8
Dividends paid in cash				(482.6)
Translation adjustment upon merger of foreign subsidiary				0.0
Other comprehensive loss					(8.4)
Balance at end of period at Sep. 30, 2021	$ 2,964.7	5.7	87.8	2,900.8	(29.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.84
Balance at beginning of period at Dec. 31, 2020		5.7	59.1	2,689.6	(21.2)
Balance at end of period at Dec. 31, 2021	$ 3,042.2	5.8	96.2	2,970.9	(30.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 1.12
Balance at beginning of period at Jun. 30, 2021		5.7	75.6	2,818.3	(18.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised			10.8
Purchases of common stock			0.0	0.0
Stock-based compensation			1.4
Net earnings	$ 243.5			243.5
Dividends paid in cash				(161.0)
Translation adjustment upon merger of foreign subsidiary				0.0
Other comprehensive loss					(10.8)
Balance at end of period at Sep. 30, 2021	$ 2,964.7	5.7	87.8	2,900.8	(29.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.28
Balance at end of period at Dec. 31, 2021	$ 3,042.2	5.8	96.2	2,970.9	(30.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.28
Stock options exercised			7.8
Purchases of common stock			(105.6)	(39.0)
Stock-based compensation			4.4
Net earnings	$ 841.3			841.3
Dividends paid in cash				(534.4)
Translation adjustment upon merger of foreign subsidiary				0.9
Other comprehensive loss					(56.4)
Balance at end of period at Sep. 30, 2022	$ 3,161.2	5.8	2.8	3,239.7	(87.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.93
Balance at beginning of period at Jun. 30, 2022		5.8	55.7	3,171.6	(54.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised			2.0
Purchases of common stock			(56.3)	(39.0)
Stock-based compensation			1.4
Net earnings	$ 284.6			284.6
Dividends paid in cash				(177.5)
Translation adjustment upon merger of foreign subsidiary				0.0
Other comprehensive loss					(32.7)
Balance at end of period at Sep. 30, 2022	$ 3,161.2	$ 5.8	$ 2.8	$ 3,239.7	$ (87.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.31