Shareholders' Equity (Schedule Of Repurchase Of Shares) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 12/14/2011 [Member]		Sep. 30, 2012 03/14/2012 [Member]	Sep. 30, 2012 06/14/2012 [Member]
Shares Repurchased [Line Items]
Date Trading Plan Initiated		Dec. 14, 2011		Mar. 14, 2012	Jun. 14, 2012
2012 Purchase Period		01/01/12-02/16/12	[1]	03/16/12-05/10/12	06/18/12-08/09/12	[2]
Trading plans purchase period date range start		01/01/12		03/16/12	06/18/12
Trading plans purchase period date range end		02/16/12		05/10/12	08/09/12
Number of Shares Repurchased		184,311		468,944	332,082
Average Price of Shares Repurchased	$ 30.28	$ 29.13		$ 29.32	$ 29.63
Total Cost		$ 5.4		$ 13.8	$ 9.8
Repurchase Authorization Year		2011		2011	2011

[1] The above table only reflects the 2012 activity under this Rule 10b5-1 trading plan. In 2011, 73,018 shares were repurchased under this Rule 10b5-1 trading plan for a total cost of $2.1 million. Total shares repurchased in 2011 and 2012 under this Rule 10b5-1 trading plan are 257,329 shares at an average price of $29.06 for a total cost of $7.5 million.

[2] During the three months ended September 30, 2012, 215,582 shares were repurchased at an average price of $30.28 for a total cost of $6.5 million.