Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2011	$ 1,990.4	$ 82.4	$ 235.1	$ 1,672.9
Balance, shares at Dec. 31, 2011		44,268,859
Changes in Shareholders' Equity
Net income	138.5			138.5
Other comprehensive income, net of tax	74.2		74.2
Common stock:
Repurchased	(10.0)	(10.0)
Shares repurchased		(279,700)
Issued under share-based compensation plans, net	17.2	17.2
Issued under share-based compensation plans net, shares		430,289
Dividends declared on common stock	(41.3)			(41.3)
Balance at Dec. 31, 2012	2,169.0	89.6	309.3	1,770.1
Balance, shares at Dec. 31, 2012		44,419,448
Changes in Shareholders' Equity
Net income	228.5			228.5
Other comprehensive income, net of tax	(174.6)		(174.6)
Common stock:
Repurchased	(82.3)	(82.3)
Shares repurchased		(1,644,488)
Issued under share-based compensation plans, net	60.7	60.7
Issued under share-based compensation plans net, shares		1,351,429
Dividends declared on common stock	(48.5)			(48.5)
Balance at Dec. 31, 2013	2,152.8	68.0	134.7	1,950.1
Balance, shares at Dec. 31, 2013		44,126,389
Changes in Shareholders' Equity
Net income	219.3			219.3
Other comprehensive income, net of tax	(20.4)		(20.4)
Common stock:
Repurchased	(147.0)	(84.5)		(62.5)
Shares repurchased		(2,383,175)
Issued under share-based compensation plans, net	21.8	21.8
Issued under share-based compensation plans net, shares		334,611
Dividends declared on common stock	(54.7)			(54.7)
Balance at Dec. 31, 2014	$ 2,171.8	$ 5.3	$ 114.3	$ 2,052.2
Balance, shares at Dec. 31, 2014		42,077,825