Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	AOCI Attributable to Parent
Balance at Dec. 31, 2019	$ 364.9	$ 0.6	$ 555.7	$ 1,008.2	$ (823.5)	$ (376.1)
Balance at Dec. 31, 2019		47,992,348
Balance at Dec. 31, 2019					14,271,047
Stock issuance, net, shares		49,777
Cash dividends - per common share	(9.9)			(9.9)
Share-based employee compensation	1.6		1.6
Net earnings (loss)	(226.2)			(226.2)
Other comprehensive income	274.4					274.4
Acquisition of treasury stock	(34.4)				$ (34.4)
Acquisition of treasury stock, shares		(382,170)			382,170
Balance at Mar. 31, 2020	370.4	$ 0.6	557.3	772.1	$ (857.9)	(101.7)
Balance at Mar. 31, 2020		47,659,955
Balance at Mar. 31, 2020					14,653,217
Balance at Dec. 31, 2020	$ 450.9	$ 0.6	553.7	869.8	$ (863.9)	(109.3)
Balance at Dec. 31, 2020	47,913,821	47,913,821
Balance at Dec. 31, 2020					14,685,510
Stock issuance, net, shares		40,278
Cash dividends - per common share	$ (10.2)			(10.2)
Share-based employee compensation	2.9		2.9
Net earnings (loss)	35.4			35.4
Other comprehensive income	4.6					4.6
Acquisition of treasury stock	(10.0)				$ (10.0)
Acquisition of treasury stock, shares		(125,635)			125,635
Balance at Mar. 31, 2021	$ 473.6	$ 0.6	$ 556.6	$ 895.0	$ (873.9)	$ (104.7)
Balance at Mar. 31, 2021	47,828,464	47,828,464
Balance at Mar. 31, 2021					14,811,145