Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)
Balance at beginning of period at Dec. 31, 2021		$ 5.8	$ 96.2	$ 2,970.9	$ (30.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised			3.9
Stock-based compensation			1.5
Net earnings	$ 269.6			269.6
Cash dividends paid				(178.4)
Translation adjustment upon merger of foreign subsidiary				0.9
Other comprehensive income					2.3
Balance at end of period at Mar. 31, 2022	$ 3,142.0	5.8	101.6	3,063.0	(28.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.31
Balance at beginning of period at Dec. 31, 2021		5.8	96.2	2,970.9	(30.7)
Balance at end of period at Dec. 31, 2022	$ 3,163.2	5.7	3.6	3,218.7	(64.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 1.24
Stock options exercised			5.9
Stock-based compensation			1.9
Net earnings	$ 295.1			295.1
Cash dividends paid				(199.8)
Translation adjustment upon merger of foreign subsidiary				0.0
Other comprehensive income					4.3
Balance at end of period at Mar. 31, 2023	$ 3,270.6	$ 5.7	$ 11.4	$ 3,314.0	$ (60.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends paid per share of common stock (in dollars per share)	$ 0.35