Fair Value Measurements - Hierarchy Table (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Warrants
Assets:
Derivative asset total		$ 2,086
Fair Value, Measurements, Recurring
Assets:
Derivative asset total	$ 260,788	308,152
Liabilities:
Total	26,517	11,862
Fair Value, Measurements, Recurring | Marketable securities
Assets:
Derivative asset total	137	220
Fair Value, Measurements, Recurring | Long-term investments
Assets:
Derivative asset total	219,156	275,836
Fair Value, Measurements, Recurring | Precious metal and commodity inventories recorded at fair value
Assets:
Derivative asset total	27,128	11,377
Fair Value, Measurements, Recurring | Economic interests in loans
Assets:
Derivative asset total	12,458	18,633
Fair Value, Measurements, Recurring | Commodity contracts on precious metal and commodity inventories
Assets:
Derivative asset total	16
Liabilities:
Financial instruments	47	381
Fair Value, Measurements, Recurring | Warrants
Assets:
Derivative asset total	1,893
Fair Value, Measurements, Recurring | Other precious metal liabilities
Liabilities:
Financial instruments	26,470	11,481
Fair Value, Measurements, Recurring | Level 1
Assets:
Derivative asset total	210,237	233,725
Liabilities:
Total	26,470	11,481
Fair Value, Measurements, Recurring | Level 1 | Marketable securities
Assets:
Derivative asset total	118	170
Fair Value, Measurements, Recurring | Level 1 | Long-term investments
Assets:
Derivative asset total	182,991	222,178
Fair Value, Measurements, Recurring | Level 1 | Precious metal and commodity inventories recorded at fair value
Assets:
Derivative asset total	27,128	11,377
Fair Value, Measurements, Recurring | Level 1 | Economic interests in loans
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 1 | Commodity contracts on precious metal and commodity inventories
Assets:
Derivative asset total	0
Liabilities:
Financial instruments	0	0
Fair Value, Measurements, Recurring | Level 1 | Warrants
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 1 | Other precious metal liabilities
Liabilities:
Financial instruments	26,470	11,481
Fair Value, Measurements, Recurring | Level 2
Assets:
Derivative asset total	35	50
Liabilities:
Total	47	381
Fair Value, Measurements, Recurring | Level 2 | Marketable securities
Assets:
Derivative asset total	19	50
Fair Value, Measurements, Recurring | Level 2 | Long-term investments
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 2 | Precious metal and commodity inventories recorded at fair value
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 2 | Economic interests in loans
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 2 | Commodity contracts on precious metal and commodity inventories
Assets:
Derivative asset total	16
Liabilities:
Financial instruments	47	381
Fair Value, Measurements, Recurring | Level 2 | Warrants
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 2 | Other precious metal liabilities
Liabilities:
Financial instruments	0	0
Fair Value, Measurements, Recurring | Level 3
Assets:
Derivative asset total	50,516	74,377
Liabilities:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Marketable securities
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 3 | Long-term investments
Assets:
Derivative asset total	36,165	53,658
Fair Value, Measurements, Recurring | Level 3 | Precious metal and commodity inventories recorded at fair value
Assets:
Derivative asset total	0	0
Fair Value, Measurements, Recurring | Level 3 | Economic interests in loans
Assets:
Derivative asset total	12,458	18,633
Fair Value, Measurements, Recurring | Level 3 | Commodity contracts on precious metal and commodity inventories
Assets:
Derivative asset total	0
Liabilities:
Financial instruments	0	0
Fair Value, Measurements, Recurring | Level 3 | Warrants
Assets:
Derivative asset total	1,893	2,086
Fair Value, Measurements, Recurring | Level 3 | Other precious metal liabilities
Liabilities:
Financial instruments	$ 0	$ 0