Guarantor and Non-Guarantor Subsidiaries Financial Information - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Mar. 11, 2016	Sep. 30, 2014
13.75% Notes due 2019 | Holdings Company
Condensed Financial Statements Captions [Line Items]
Interest rate	13.75%
Due date of Senior Secured Notes	2019
5.625% Senior Secured Notes due 2022
Condensed Financial Statements Captions [Line Items]
Interest rate		5.625%		5.625%
5.625% Senior Secured Notes due 2022 | Acquisition Corp.
Condensed Financial Statements Captions [Line Items]
Interest rate	5.625%	5.625%
Due date of Senior Secured Notes	2022	2022
6.00% Senior Secured Notes due 2021 | Acquisition Corp.
Condensed Financial Statements Captions [Line Items]
Interest rate	6.00%	6.00%
Due date of Senior Secured Notes	2021	2021
6.25% Senior Secured Notes due 2021 | Acquisition Corp.
Condensed Financial Statements Captions [Line Items]
Interest rate	6.25%	6.25%
Due date of Senior Secured Notes	2021	2021
6.75% Senior Notes due 2022 | Acquisition Corp.
Condensed Financial Statements Captions [Line Items]
Interest rate	6.75%		6.75%
Due date of Senior Secured Notes	2022