Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 166,224	$ 192,017
Federal and state credit carryforwards	43,897	46,721
Accrued expenses and other reserves	33,150	41,371
Deferred Tax Assets, Deferred Income	24,832	81,647
Deferred compensation	22,917	19,315
Other	11,579	13,802
Total deferred tax assets	490,919	394,873
Valuation allowance for deffered tax assets	(303,378)	(183,295)
Net deferred tax assets	187,541	211,578
Deferred tax liabilities:
Depreciation	(16,833)	(15,729)
Convertible debt	(87,046)	(92,452)
Acquired intangibles	(7,517)	(131,959)
Reported as:
Short-term deferred tax asset	130,361	21,369
Long-term deferred tax liability	(54,216)	(49,931)
Deferred Tax Liabilities, Net	$ 76,145	$ (28,562)