Condensed Consolidated Statements Of Shareholders' Equity (USD $) In Millions, except Share data	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at beginning of year at Dec. 31, 2011	$ 0.6	$ 1,467.5	$ 77.1	$ (415.0)	$ 1,130.2
Balance at beginning of year, shares at Dec. 31, 2011	58,424,691
Stock issuance	387,493
Share-based employee compensation		16.2			16.2
Net earnings			60.0		60.0
Dividends declared			(95.3)		(95.3)
Dividends declared in excess of retained earnings		(412.9)			(412.9)
Other comprehensive income (loss)				(2.7)	(2.7)
Balance at end of period at Jun. 30, 2012	0.6	1,070.8	41.8	(417.7)	695.5
Balance at end of period, shares at Jun. 30, 2012	58,812,184
Balance at beginning of year at Dec. 31, 2012	0.6	1,076.8	113.1	(471.4)	719.1
Balance at beginning of year, shares at Dec. 31, 2012	58,934,050
Stock issuance	247,826
Share-based employee compensation		10.4			10.4
Net earnings			32.9		32.9
Other comprehensive income (loss)				16.5	16.5
Balance at end of period at Jun. 30, 2013	$ 0.6	$ 1,087.2	$ 146.0	$ (454.9)	$ 778.9
Balance at end of period, shares at Jun. 30, 2013	59,181,876