Quarterly Information (Unaudited) - Additional Disclosures (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended				12 Months Ended
	Jul. 31, 2017	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Quarterly Financial Data [Line Items]
Benefit associated with expiration of statute of limitations on uncertain tax positions			$ 3,300	$ 1,600		$ 4,402	$ 0	$ 0
Charge resulting from remeasured deferred tax asset		$ 1,900		$ 2,800		2,100
Gain on restructured notes receivable					$ (3,000)	0	3,048	0
Loss on extinguishment of debt						0	$ 5,250	0
Shareholder Derivative Litigation | Beneficial Owner
Quarterly Financial Data [Line Items]
Settlement awarded to other party			6,500
Settlement fee			1,300
Remaining settlement amount			$ 5,200
Convertible Senior Notes
Quarterly Financial Data [Line Items]
Loss on extinguishment of debt					5,300
Early repayment of principal	$ 35,000				$ 35,000
Cash Converters International Limited | United Kingdom
Quarterly Financial Data [Line Items]
Impairment of investments						11,700		11,000
Impairment of investments, net of tax						$ 9,200		$ 7,200