Short-term Debt	3 Months Ended
Dec. 31, 2016
Short-term Debt [Abstract]
Short-term Debt	Short-term Debt Our short-term debt obligations primarily consist of commercial paper borrowings. Commercial paper borrowings outstanding were $408.1 million and $448.6 million at December 31, 2016 and September 30, 2016, respectively. The weighted average interest rate of the commercial paper outstanding was 0.81 percent and 0.57 percent at December 31, 2016 and September 30, 2016, respectively. The current portion of long-term debt consists of our $250.0 million, 5.65% notes, due in December 2017. These notes were included within long-term debt at September 30, 2016 but are included within current liabilities at December 31, 2016 as they are due within the next twelve months. At December 31, 2016 and September 30, 2016, our total borrowing capacity under our unsecured revolving credit facility expiring in March 2020 was $1.0 billion. We did not borrow against this credit facility during the three months ended December 31, 2016 or the twelve months ended September 30, 2016. In December 2016, we amended the financial covenant under this credit facility. The previous financial covenant, which limited our debt-to-total-capital ratio to 60 percent, was replaced with a minimum EBITDA-to-interest ratio of 3.0 to 1.0. The EBITDA-to-interest ratio is defined in the amendment as the ratio of consolidated EBITDA (as defined in the amendment) for the preceding four quarters to consolidated interest expense for the same period.

Short-term Debt

Our short-term debt obligations primarily consist of commercial paper borrowings. Commercial paper borrowings outstanding were $408.1 million and $448.6 million at December 31, 2016 and September 30, 2016, respectively. The weighted average interest rate of the commercial paper outstanding was 0.81 percent and 0.57 percent at December 31, 2016 and September 30, 2016, respectively.

The current portion of long-term debt consists of our $250.0 million, 5.65% notes, due in December 2017. These notes were included within long-term debt at September 30, 2016 but are included within current liabilities at December 31, 2016 as they are due within the next twelve months.

At December 31, 2016 and September 30, 2016, our total borrowing capacity under our unsecured revolving credit facility expiring in March 2020 was $1.0 billion. We did not borrow against this credit facility during the three months ended December 31, 2016 or the twelve months ended September 30, 2016. In December 2016, we amended the financial covenant under this credit facility. The previous financial covenant, which limited our debt-to-total-capital ratio to 60 percent, was replaced with a minimum EBITDA-to-interest ratio of 3.0 to 1.0. The EBITDA-to-interest ratio is defined in the amendment as the ratio of consolidated EBITDA (as defined in the amendment) for the preceding four quarters to consolidated interest expense for the same period.