Debt - Interest Rates - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2016
Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	1.00%
Interest rate applicable to overdue principal	2.00%
Description of variable rate basis	The loans under the Revolving Credit Facility bear interest at Revolving Borrower’s election at a rate equal to (i) the rate for deposits in the borrowing currency in the London interbank market (adjusted for maximum reserves) for the applicable interest period (“Revolving LIBOR”), plus 2.00% per annum, or (ii) the base rate, which is the highest of (x) the corporate base rate established by the administrative agent from time to time, (y) 0.50% in excess of the overnight federal funds rate and (z) the one-month Revolving LIBOR plus 1.0% per annum, plus, in each case, 1.00% per annum. If there is a payment default at any time, then the interest rate applicable to overdue principal will be the rate otherwise applicable to such loan plus 2.0% per annum.
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	2.00%
Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	1.00%
Additional Interest rate on other overdue amounts	2.00%
Revolving Credit Facility | Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	0.50%
Senior Term Loan Facility due 2020
Debt Instrument [Line Items]
Interest rate applicable to overdue principal	2.00%
Description of variable rate basis	The loans under the Senior Term Loan Facility bear interest at Term Loan Borrower’s election at a rate equal to (i) the rate for deposits in U.S. dollars in the London interbank market (adjusted for maximum reserves) for the applicable interest period (“Term Loan LIBOR”), plus 2.75% per annum, or (ii) the base rate, which is the highest of (x) the corporate base rate established by the administrative agent as its prime rate in effect at its principal office in New York City from time to time, (y) 0.50% in excess of the overnight federal funds rate and (z) one-month Term Loan LIBOR, plus 1.00% per annum, plus, in each case, 1.75% per annum.
Term loan Base rate plus Election Rate	1.00%
Senior Term Loan Facility due 2020 | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	2.75%
Senior Term Loan Facility due 2020 | Base Rate
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	1.75%
Additional Interest rate on other overdue amounts	2.00%
Senior Term Loan Facility due 2020 | Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Debt instrument, marginal interest rate	0.50%