Fair Value Measurements - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 31, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018
Notes receivable from Grupo Finmart, net | Carrying Value
Financial assets:
Financial assets		$ 18,744	$ 37,425	$ 51,338
Notes receivable from Grupo Finmart, net | Estimated Fair Value
Financial assets:
Financial assets		19,517	41,153	57,116
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		19,517	41,153	57,116
Zero-coupon convertible promissory note due January 2021 | Carrying Value
Financial assets:
Financial assets		7,226
Zero-coupon convertible promissory note due January 2021 | Estimated Fair Value
Financial assets:
Financial assets		7,226
Zero-coupon convertible promissory note due January 2021 | Estimated Fair Value | Level 1
Financial assets:
Financial assets		0
Zero-coupon convertible promissory note due January 2021 | Estimated Fair Value | Level 2
Financial assets:
Financial assets		0
Zero-coupon convertible promissory note due January 2021 | Estimated Fair Value | Level 3
Financial assets:
Financial assets		$ 7,226
2.89% promissory note receivable due April 2024
Financial liabilities:
Interest on note receivable	2.89%	2.89%
2.89% promissory note receivable due April 2024 | Carrying Value
Financial assets:
Financial assets		$ 1,108
2.89% promissory note receivable due April 2024 | Estimated Fair Value
Financial assets:
Financial assets		1,108
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 1
Financial assets:
Financial assets		0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 2
Financial assets:
Financial assets		0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 3
Financial assets:
Financial assets		1,108
Investments in unconsolidated affiliates | Carrying Value
Financial assets:
Financial assets		30,922	49,500	61,056
Investments in unconsolidated affiliates | Estimated Fair Value
Financial assets:
Financial assets		27,158	49,500	49,205
Investments in unconsolidated affiliates | Estimated Fair Value | Level 1
Financial assets:
Financial assets		24,464	49,500	49,205
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		2,694	0	0
2019 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities			187,433	184,823
2019 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities			189,150	197,925
2019 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities			0	0
2019 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities			189,150	197,925
2019 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities			0	0
2024 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities		109,909	105,858	104,562
2024 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities		161,719	180,399	195,974
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		161,719	180,399	195,974
2024 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities		0	0	0
2025 Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities		124,542	119,736
2025 Convertible Notes | Estimated Fair Value
Financial liabilities:
Financial liabilities		159,873	161,253	168,464
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		159,873	161,253	168,464
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		$ 1,148	1,304
8.5% unsecured debt due 2024 | Estimated Fair Value
Financial liabilities:
Financial liabilities		1,148	1,304
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities		0	0
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities		0	0
8.5% unsecured debt due 2024 | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities		1,148	$ 1,304
CASHMAX secured borrowing facility | Carrying Value
Financial liabilities:
Financial liabilities		65
CASHMAX secured borrowing facility | Estimated Fair Value
Financial liabilities:
Financial liabilities		804
CASHMAX secured borrowing facility | Estimated Fair Value | Level 1
Financial liabilities:
Financial liabilities		0
CASHMAX secured borrowing facility | Estimated Fair Value | Level 2
Financial liabilities:
Financial liabilities		0
CASHMAX secured borrowing facility | Estimated Fair Value | Level 3
Financial liabilities:
Financial liabilities		$ 804