Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) (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]
Balance at beginning of year	$ 17,464	$ 19,630	$ 46,648
Additions for (reductions in) tax positions related to current year	150	(1,620)	903
Additions for tax positions related to prior years	1,365	0	0
Reductions for tax positions of prior years	(14,201)	0	(27,181)
Lapse of statute of limitations	(162)	(546)	(740)
Balance at end of year	$ 4,616	$ 17,464	$ 19,630