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, 2018	$ 226.0	$ 0.6	$ 547.4	$ 829.8	$ (692.2)	$ (459.6)
Balance at Dec. 31, 2018		48,808,239
Balance at Dec. 31, 2018					12,745,485
Cumulative effect impact of ASU adoption | ASU 2017-12 [Member]	0.1			(0.1)		0.1
Stock issuance, net		164,082
Cash dividends - per common share	(8.9)			(8.9)
Share-based employee compensation	5.9		5.9
Net earnings (loss)	39.1			39.1
Other comprehensive income	3.0					3.0
Acquisition of treasury stock	(20.0)				$ (20.0)
Acquisition of treasury stock, shares		(331,686)			331,686
Balance at Mar. 31, 2019	245.1	$ 0.6	553.3	859.9	$ (712.2)	(456.5)
Balance at Mar. 31, 2019		48,640,635
Balance at Mar. 31, 2019					13,077,171
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	47,992,348
Balance at Dec. 31, 2019					14,271,047
Stock issuance, net		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	47,659,955
Balance at Mar. 31, 2020					14,653,217