v2.4.0.6
Senior Long-Term Debt (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2012
4.90% Unsecured Senior Notes [Member]
July 2, 2012 Issuance Of 4.90% Unsecured Senior Notes [Member]
Jul. 02, 2012
4.90% Unsecured Senior Notes [Member]
July 2, 2012 Issuance Of 4.90% Unsecured Senior Notes [Member]
Sep. 30, 2012
7.50% Unsecured Senior Debentures [Member]
August 1, 2012 Redemption Of 7.50% Unsecured Senior Debentures [Member]
Sep. 30, 2012
7.50% Unsecured Senior Debentures [Member]
August 1, 2012 Redemption Of 7.50% Unsecured Senior Debentures [Member]
Sep. 30, 2012
6.80% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]          
Debt instrument, face amount   $ 350 $ 150 $ 150  
Debt instrument, interest rate, stated percentage 4.90%   7.50% 7.50% 6.80%
Proceeds from issuance of unsecured debt 347.2        
Debt instrument, redemption price, percentage of face amount     100.00% 100.00%  
Loss on extinguishment of debt     (4.1) (4.1)  
Debt instrument, principal amount outstanding         $ 246.7