Financing (Textuals) (Details)	Sep. 08, 2012
Senior notes [Member] | 5.80% Senior Notes due 2012, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	5.80%
Senior notes [Member] | 6.25% Senior Notes due 2014, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	6.25%
Senior notes [Member] | 5.625% Senior Notes due 2014, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	5.625%
Senior notes [Member] | 3.40% Senior Notes due 2016, unsecured
Debt Instrument [Line Items]
Fixed interest rate of debt	3.40%
Senior notes [Member] | 6.35% Senior Notes due 2017, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	6.35%
Senior notes [Member] | 5.0% Senior Notes due 2019, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	5.00%
Senior notes [Member] | 3.95% Senior Notes due 2020, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	3.95%
Senior notes [Member] | 4.75% Senior Notes due 2021, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	4.75%
Second series notes [Member] | 3.00% Second Series Notes due 2014 unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	3.00%
Senior Debentures [Member] | 7.45% Senior Debentures due 2027, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	7.45%
Senior Debentures [Member] | 7.25% Senior Debentures due 2031, unsecured [Member]
Debt Instrument [Line Items]
Fixed interest rate of debt	7.25%