Debt Of The Company (Details)	3 Months Ended
	Mar. 31, 2013
Exchangeable Senior Debentures [Member] | 5.50% Exchangeable Senior Debentures Due 2029 [Member]
Debt Instrument [Line Items]
Interest rate	5.50%
Maturity date	2029
Senior Notes [Member] | 4.50% Notes Due 2015 [Member]
Debt Instrument [Line Items]
Interest rate	4.50%
Maturity date	2015
Senior Notes [Member] | 5.875% Notes Due 2020 [Member]
Debt Instrument [Line Items]
Interest rate	5.875%
Maturity date	2020
Senior Notes [Member] | 5.250% Notes Due 2021 [Member]
Debt Instrument [Line Items]
Interest rate	5.25%
Maturity date	2021
Senior Notes [Member] | 3.625% Notes Due 2022 [Member]
Debt Instrument [Line Items]
Interest rate	3.625%
Maturity date	2022
Senior Notes [Member] | 4.250% Notes Due 2025 [Member]
Debt Instrument [Line Items]
Interest rate	4.25%
Maturity date	2025