Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits at beginning of year	$ 9,009	$ 7,501	$ 9,539
Gross increases for tax positions in prior years	2,468	508	64
Gross decreases for tax positions in prior years	(967)	0	(2,035)
Gross increases based on tax positions related to the current year	923	1,000	681
Decreases for settlements and payments	(6,879)	0	(748)
Gross unrecognized tax benefits at end of year	$ 4,554	$ 9,009	$ 7,501