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, 2017	$ 419.3	$ 0.6	$ 516.8	$ 633.4	$ (385.6)	$ (345.9)
Balance at Dec. 31, 2017		52,772,139
Balance at Dec. 31, 2017					8,010,597
Cumulative effect impact of ASU adoption | ASU 2018-02 [Member]	(54.3)			54.3		(54.3)
Stock issuance, net		591,584
Share-based employee compensation	15.2		15.2
Net earnings	27.8			27.8
Other comprehensive income	11.5					11.5
Acquisition of treasury stock	(70.0)				$ (70.0)
Acquisition of treasury stock, shares		(1,165,247)			1,165,247
Balance at Mar. 31, 2018	403.8	$ 0.6	532.0	715.5	$ (455.6)	(388.7)
Balance at Mar. 31, 2018		52,198,476
Balance at Mar. 31, 2018					9,175,844
Balance at Dec. 31, 2018	$ 261.2	$ 0.6	547.4	865.0	$ (692.2)	(459.6)
Balance at Dec. 31, 2018	48,808,239	48,808,239
Balance at Dec. 31, 2018	12,745,485				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 - $0.175 per common share	(8.9)			(8.9)
Share-based employee compensation	5.9		5.9
Net earnings	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	$ 280.3	$ 0.6	$ 553.3	$ 895.1	$ (712.2)	$ (456.5)
Balance at Mar. 31, 2019	48,640,635	48,640,635
Balance at Mar. 31, 2019	13,077,171				13,077,171