Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Deferred Tax Assets:
Warranty and other reserves	$ 12,408	$ 11,752
Incentive compensation	16,285	15,338
Property, equipment and other assets	2,647	2,734
Federal and state carryforwards	365,283	305,909
Inventory adjustments	133,843	143,746
Uncertain tax positions	16,331	45,303
Other	4,285	11,315
Total deferred tax assets	551,082	536,097
Deferred Tax Liabilities:
Deferred revenues	(56,017)	(54,052)
Total deferred tax liabilities	(56,017)	(54,052)
Net deferred tax assets before valuation allowance	495,065	482,045
Valuation allowance	(488,217)	(479,285)
Net deferred tax assets	$ 6,848	$ 2,760