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, 2010	$ 0.6	$ 1,451.2	$ (35.3)	$ (325.7)	$ 1,090.8
Common stock shares, beginning balance at Dec. 31, 2010	58,070,807
Stock issuance	333,660
Share-based employee compensation		13.3			13.3
Net earnings			103.9		103.9
Other comprehensive income (loss)				4.3	4.3
Balance at end of period at Sep. 30, 2011	0.6	1,464.5	68.6	(321.4)	1,212.3
Common stock shares, ending balance at Sep. 30, 2011	58,404,467
Balance at beginning of year at Dec. 31, 2011	0.6	1,467.5	77.1	(415.0)	1,130.2
Common stock shares, beginning balance at Dec. 31, 2011	58,424,691
Stock issuance	397,640
Share-based employee compensation		20.3			20.3
Net earnings			122.9		122.9
Dividends			(95.3)		(508.2)
Dividends		(412.9)
Other comprehensive income (loss)				7.5	7.5
Balance at end of period at Sep. 30, 2012	$ 0.6	$ 1,074.9	$ 104.7	$ (407.5)	$ 772.7
Common stock shares, ending balance at Sep. 30, 2012	58,822,331