Debt and Credit Facilities (Applicable Margin for Borrowings) (Detail) (USD $)			3 Months Ended											3 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013 Term Loan Facility Due August Seventh Twenty Ninteen [Member]	Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2013 Revolving Credit Facility [Member] Minimum	Dec. 31, 2013 Revolving Credit Facility [Member] Maximum	Dec. 31, 2013 Base Rate Margin Term Loan Facility Due August Seventh Twenty Ninteen [Member]	Dec. 31, 2013 Base Rate Margin Revolving facility due March 2015 Minimum		Dec. 31, 2013 Base Rate Margin Revolving facility due March 2015 Maximum		Dec. 31, 2013 LIBOR Margin Term Loan Facility Due August Seventh Twenty Ninteen [Member]	Dec. 31, 2013 LIBOR Margin Term loans maturing March 2013	Dec. 31, 2013 LIBOR Margin Revolving facility due March 2015 Minimum		Dec. 31, 2013 LIBOR Margin Revolving facility due March 2015 Maximum		Dec. 31, 2013 Debt Instrument Amended And Restated [Member] Term loans maturing March 2016
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 75,000,000
Applicable margin rate			2.75%				1.75%	0.50%	[1]	0.75%	[1]	2.75%		1.50%	[1]	1.75%	[1]
Letters of credit, outstanding				7,200,000
Debt Instrument, Interest Rate, Effective Percentage													2.92%
Credit Facility, net of unamortized discount of $1.1 million and $1.2 million, respectively.	$ 479,875,000	$ 481,016,000																$ 481,000,000
Credit facility, commitment fee percentage for unused capacity				0.375%	0.375%	0.50%

[1] The margin is determined based on our net leverage ratio at the date the interest rates are reset on the revolving credit line.