Debt - Credit Facility (Details)		3 Months Ended		6 Months Ended
	Mar. 25, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Weighted average interest rate		4.30%		4.30%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Minimum interest expense coverage ratio	1.15
Minimum liquidity financial covenant	$ 150,000,000
Long-term line of credit, reduction in borrowing capacity		$ 152,000,000		$ 152,000,000
Long-term line of credit, maximum borrowing capacity		1,395,000,000		1,395,000,000
Long-term line of credit		960,000,000		960,000,000
Long-term line of credit, remaining borrowing capacity		435,000,000		435,000,000
Interest costs capitalized		3,800,000	$ 4,000,000	8,400,000	$ 9,000,000
Revolving Credit Facility | Minimum | Eurodollar
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.50%
Unused capacity commitment fee	1.00%
Revolving Credit Facility | Maximum | Eurodollar
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.25%
Unused capacity commitment fee	1.30%
Revolving Credit Facility, Maturing May 2018 | Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term line of credit, maximum borrowing capacity	$ 1,395,000,000.000	275,000,000		275,000,000
Revolving Credit Facility, Maturing May 2019 | Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term line of credit, maximum borrowing capacity	1,120,500,000.0000	$ 1,120,000,000		$ 1,120,000,000
Junior Lien | Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term line of credit, maximum borrowing capacity	$ 400,000,000