Income Taxes - Classification of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Line Items]
Total deferred tax assets	$ 413,971	$ 491,547
Deferred tax liabilities	(30,939)	(43,496)
Net deferred tax assets before valuation allowance	383,032	448,051
Valuation allowance	(57,659)	(445,228)
Net deferred tax assets	325,373	$ 2,823
Subject to annual limitation
Income Tax Disclosure [Line Items]
Total deferred tax assets	93,741
Generally not subject to annual limitation
Income Tax Disclosure [Line Items]
Total deferred tax assets	$ 320,230