Debt (Schedule of Carrying Values of Long-Term Debt) (Parenthetical) (Details)	Sep. 30, 2014
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term debt instrument, weighted average interest rate	2.80%
Notes Payable [Member] | Equipment [Member]
Debt Instrument [Line Items]
Long-term debt instrument, weighted average interest rate	2.90%
Unsecured Debt [Member] | Senior Notes [Member] | 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.875%
Unsecured Debt [Member] | Convertible Debt [Member] | 2011 4.0% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%
Unsecured Debt [Member] | Convertible Debt [Member] | 2009 4.0% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%
Unsecured Debt [Member] | Convertible Debt [Member] | 2011 4.25% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.25%
Unsecured Debt [Member] | Convertible Debt [Member] | 2009 4.25% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.25%