Changes in Accumulated Other Comprehensive Loss by Component, Net of Income Tax (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Accumulated Other Comprehensive Loss [Line Items]
Balance, September 30, 2011	$ (32,037)	$ (23,945)
Current year other comprehensive income (loss)	16,578	(8,092)	(7,037)
Balance, September 30, 2012	(15,459)	(32,037)	(23,945)
Defined Benefit Pension Plans
Accumulated Other Comprehensive Loss [Line Items]
Balance, September 30, 2011	(32,037)	(23,470)
Current year other comprehensive income (loss)	16,420	(8,567)
Balance, September 30, 2012	(15,617)	(32,037)
Cash Flow Hedge
Accumulated Other Comprehensive Loss [Line Items]
Current year other comprehensive income (loss)	158
Balance, September 30, 2012	158
Foreign Currency Items
Accumulated Other Comprehensive Loss [Line Items]
Balance, September 30, 2011		(475)
Current year other comprehensive income (loss)		$ 475