Fair Value (Narrative) (Details) (USD $)	Jun. 30, 2013	Jun. 21, 2013	Sep. 30, 2012	Jan. 18, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	$ 1,338,500,000		$ 830,000,000
Senior Notes [Member] | 6.5% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	658,500,000		450,000,000
Principal amount	650,000,000	650,000,000		450,000,000
Long-term debt, fair value	$ 663,900,000
Interest Rate Swap [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit valuation adjustment to total fair value percentage (less than 1%)	1.00%