Fair Value Measurements - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Notes receivable from Grupo Finmart, net | Carrying Value
Financial assets:
Financial assets	$ 7,450	$ 7,182	$ 31,310
Notes receivable from Grupo Finmart, net | Estimated Fair Value
Financial assets:
Financial assets	7,729	7,582	33,710
Notes receivable from Grupo Finmart, net | Estimated Fair Value | Level 1
Financial assets:
Financial assets	0	0	0
Notes receivable from Grupo Finmart, net | Estimated Fair Value | Level 2
Financial assets:
Financial assets	0	0	0
Notes receivable from Grupo Finmart, net | Estimated Fair Value | Level 3
Financial assets:
Financial assets	$ 7,729	7,582	33,710
2.89% promissory note receivable due April 2024
Financial liabilities:
Interest on note receivable	2.89%
2.89% promissory note receivable due April 2024 | Carrying Value
Financial assets:
Financial assets	$ 1,124	1,117
2.89% promissory note receivable due April 2024 | Estimated Fair Value
Financial assets:
Financial assets	1,124	1,117
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 1
Financial assets:
Financial assets	0	0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 2
Financial assets:
Financial assets	0	0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 3
Financial assets:
Financial assets	1,124	1,117
Investments in unconsolidated affiliates | Carrying Value
Financial assets:
Financial assets	29,272	34,516	35,511
Investments in unconsolidated affiliates | Estimated Fair Value
Financial assets:
Financial assets	42,460	28,308	35,511
Investments in unconsolidated affiliates | Estimated Fair Value | Level 1
Financial assets:
Financial assets	34,555	20,252	35,511
Investments in unconsolidated affiliates | Estimated Fair Value | Level 2
Financial assets:
Financial assets	0	0	0
Investments in unconsolidated affiliates | Estimated Fair Value | Level 3
Financial assets:
Financial assets	7,905	8,056	0
2019 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities			190,076
2019 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities			190,613
2019 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities			0
2019 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities			190,613
2019 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities			0
2024 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities	112,740	111,311	107,182
2024 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities	136,634	139,969	145,202
2024 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities	0	0	0
2024 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities	136,634	139,969	145,202
2024 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities	0	0	0
2025 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities	127,902	126,210	121,316
2025 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities	136,965	138,345	134,447
2025 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities	0	0	0
2025 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities	136,965	138,345	134,447
2025 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities	$ 0	0	0
8.5% unsecured debt due 2024
Financial liabilities:
Stated interest rate	8.50%
8.5% unsecured debt due 2024 | Carrying Value
Financial liabilities:
Financial liabilities	$ 1,042	1,092	1,237
8.5% unsecured debt due 2024 | Estimated Fair Value
Financial liabilities:
Financial liabilities	1,042	1,092	1,237
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities	0	0	0
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities	0	0	0
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities	1,042	1,092	1,237
CASHMAX secured borrowing facility | Carrying Value
Financial liabilities:
Financial liabilities	(260)	(19)	334
CASHMAX secured borrowing facility | Estimated Fair Value
Financial liabilities:
Financial liabilities	404	634	1,160
CASHMAX secured borrowing facility | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities	0	0	0
CASHMAX secured borrowing facility | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities	0	0	0
CASHMAX secured borrowing facility | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities	$ 404	$ 634	$ 1,160