Unaudited Condensed Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Accumulated Other Comprehensive Income	Retained Earnings
Changes in Shareholders' Equity
Cumulative effect adjustment- ASU 2014-01	$ (7.2)			$ (7.2)
Balance at Dec. 31, 2013	2,145.6	$ 68.0	$ 134.7	1,942.9
Balance, shares at Dec. 31, 2013		44,126,389
Changes in Shareholders' Equity
Net income	210.3			210.3
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 ($1.30 per share)	(54.7)			(54.7)
Balance at Dec. 31, 2014	2,155.6	$ 5.3	114.3	2,036.0
Balance, shares at Dec. 31, 2014		42,077,825
Changes in Shareholders' Equity
Net income	176.0			176.0
Other comprehensive income, net of tax	(77.6)		(77.6)
Common stock:
Repurchased	0.0	$ 0.0		0.0
Shares repurchased		0
Issued under share-based compensation plans, net	18.0	$ 18.0
Issued under share-based compensation plans net, shares		264,479
Balance at Sep. 30, 2015	$ 2,272.0	$ 23.3	$ 36.7	$ 2,212.0
Balance, shares at Sep. 30, 2015		42,342,304