Schedule of Changes in Components of Unrecognized Benefit Plan Costs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Pension Plans
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	$ (21,817)	$ 14,443
Prior service costs	298
Net actuarial loss from previous years	(3,590)	(2,549)
Prior service costs	(70)	(63)
Income tax benefits related to above items	9,631	(4,732)
Changes in unrecognized benefit plan costs	(15,548)	7,099
SERP
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	(616)	2,867
Net actuarial loss from previous years	(376)
Prior service costs	(420)	(420)
Income tax benefits related to above items	540	(979)
Changes in unrecognized benefit plan costs	$ (872)	$ 1,468