Consolidated Statements Of Changes in Shareholders’ Equity - USD ($) $ in Millions	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2016	$ 348.8	$ 575.4	$ (196.6)	$ 3.3	$ 730.9
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net Income		71.6		0.3	71.9
Other comprehensive (loss) income			(10.0)	0.2	(9.8)
Stock issued	17.4			0.6	18.0
Stock purchased	(13.7)			(0.3)	(14.0)
Dividends declared	35.2
Dividends declared		(70.6)			(35.4)
Balance at Dec. 31, 2017	387.7	619.9	(250.1)	4.1	761.6
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Adoption of ASU 2018-02		43.5	(43.5)
Net Income		143.3		0.4	143.7
Other comprehensive (loss) income			9.8	(0.3)	9.5
Stock issued	17.8				17.8
Stock purchased	(15.7)			(0.3)	(16.0)
Dividends declared	39.0
Dividends declared		(85.9)			(46.9)
Balance at Dec. 31, 2018	428.8	678.1	(240.3)	3.9	870.5
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Adoption of ASU 2018-02		0.8			0.8
Net Income		144.5		0.4	144.9
Other comprehensive (loss) income			(10.3)	0.1	(10.2)
Stock issued	18.5			0.8	19.3
Stock purchased	(19.2)			(0.3)	(19.5)
Dividends declared	21.4
Dividends declared		(128.6)			(107.2)
Balance at Dec. 31, 2019	$ 449.5	$ 694.0	$ (250.6)	$ 4.9	$ 897.8