Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Deferred Tax Assets:
Warranty and other reserves	$ 11,559	$ 12,408
Incentive compensation	17,368	16,285
Property, equipment and other assets	2,455	2,647
Federal and state carryforwards	383,508	365,283
Inventory adjustments	114,416	133,843
Uncertain tax positions	14,415	16,331
Other	3,052	4,285
Total deferred tax assets	546,773	551,082
Deferred Tax Liabilities:
Deferred revenues	(54,257)	(56,017)
Total deferred tax liabilities	(54,257)	(56,017)
Net deferred tax assets before valuation allowance	492,516	495,065
Valuation allowance	(487,263)	(488,217)
Net deferred tax assets	$ 5,253	$ 6,848