Condensed Consolidating Financial Information (Details)	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2013
Long-term debt
Ownership percentage in guarantor subsidiaries	100.00%
Maximum percentage of ownership interest below which subsidiaries are considered non-guaranteeing	100.00%
7.25% Senior notes, due January 2019
Long-term debt
Interest rate on long-term debt (as a percent)	7.25%	7.25%	7.25%