Shareholders' Equity (Schedule Of Share Repurchases) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
	Apr. 19, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 500.0
Shares repurchased, shares		2,491,355	4,776,224	3,952,243	6,047,437
Cost of shares repurchased		$ 90.0	$ 194.4	$ 140.0	$ 245.3
Shares repurchased, average price per share		$ 36.12	$ 40.69	$ 35.42	$ 40.56
Treasury shares held for issuance pursuant to equity-based compensation plans	3,000,000
Exor SA [Member]
Class of Stock [Line Items]
Shares repurchased, shares			4,053,537
Cost of shares repurchased			$ 164.4
Shares repurchased, average price per share			$ 40.546