Guarantor And Non-Guarantor Subsidiaries Financial Information - Consolidating Statement of Cash Flows (Parenthetical) (Detail)	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
5.00% Senior Secured Notes
Condensed Cash Flow Statements Captions [Line Items]
Interest rate	5.00%	5.00%	5.00%
5.625% Senior Secured Notes
Condensed Cash Flow Statements Captions [Line Items]
Interest rate		5.625%	5.625%
13.75% Senior Notes due 2019
Condensed Cash Flow Statements Captions [Line Items]
Interest rate	13.75%	13.75%	13.75%
6.750% Senior Notes
Condensed Cash Flow Statements Captions [Line Items]
Interest rate	6.75%	6.75%	6.75%
11.5% Senior Unsecured Notes
Condensed Cash Flow Statements Captions [Line Items]
Interest rate	11.50%	11.50%	11.50%