Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Millions, except Share data	Total	Common Stock	Accumulated Other Comprehensive Income	Retained Earnings
Balance at Dec. 31, 2009	$ 1,735.4	$ 220.4	$ 71.4	$ 1,443.6
Balance, shares at Dec. 31, 2009		47,744,524
Net income	189.0			189.0
Other comprehensive income, net of tax	89.5		89.5
Common stock:
Repurchased	(81.8)	(81.8)
Shares repurchased		(2,034,200)
Issued under share-based compensation plans, net	19.6	19.6
Issued under share-based compensation plans net, shares		449,063
Dividends declared on common stock	(39.6)			(39.6)
Balance at Dec. 31, 2010	1,912.1	158.2	160.9	1,593.0
Balance, shares at Dec. 31, 2010		46,159,387
Net income	100.0			100.0
Other comprehensive income, net of tax	98.8		98.8
Common stock:
Repurchased	(90.0)	(90.0)
Shares repurchased		(2,170,000)
Issued under share-based compensation plans, net	10.5	10.5
Issued under share-based compensation plans net, shares		197,045
Balance at Sep. 30, 2011	$ 2,031.4	$ 78.7	$ 259.7	$ 1,693.0
Balance, shares at Sep. 30, 2011		44,186,432