ACCOUNTING POLICIES (Details 3)	12 Months Ended
	Dec. 31, 2017 USD ($) subsidiary	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Fixed assets
Depreciation of fixed assets	$ 28,848,000	$ 27,283,000	$ 23,516,000
Cost and equity method investments
Number of cost method investments	7
Carrying value of cost method investments	$ 6,500,000	11,800,000
Impairment of cost method investments	$ 5,487,000	2,850,000	0
Number of equity method investments	3
Carrying value of equity method investments	$ 6,500,000
Number of broker-dealer subsidiary (in subsidiary)	2
Proceeds from security token offering	$ 905,000	0	0
Precious metals
Unrealized gain (loss) on investment of precious metals	0	0	(1,183,000)
Realized Gain (Loss) on Investment in Precious Metals	1,971,000	201,000	0
Goodwill
Impairments of goodwill	0	0	0
Intangible assets other than goodwill
Acquired intangible assets	16,000,000	16,000,000
Intangible assets, other	1,779,000	1,356,000
Total intangible assets, gross	17,779,000	17,356,000
Accumulated amortization of intangible assets	(10,442,000)	(6,443,000)
Total intangible assets, net	7,337,000	10,913,000
Amortization of intangible assets	3,999,000	3,968,000	1,581,000
Estimated amortization expense for the next five years
2017	3,000,000
2018	2,100,000
2109	1,300,000
2020	915,000
2021	20,000
Thereafter	$ 29,000
Weighted average remaining useful life for intangible assets	2 years 8 months 20 days
Impairments of long-lived assets	$ 0	0	0
Gain on sale of cryptocurrencies	4,816,000	0	0
Gain on noncash sale of cryptocurrencies	1,995,000	0	0
Cryptocurrency, bitcoin
Estimated amortization expense for the next five years
Cryptocurrency denominated assets	1,512,000	307,000
Cost of goods sold — direct
Fixed assets
Depreciation of fixed assets	307,000	310,000	283,000
Technology
Fixed assets
Depreciation of fixed assets	24,604,000	25,693,000	22,126,000
Intangible assets other than goodwill
Amortization of intangible assets	3,620,000	2,904,000	605,000
Sales and marketing
Fixed assets
Depreciation of fixed assets	0	124,000	0
Intangible assets other than goodwill
Amortization of intangible assets	83,000	1,008,000	531,000
General and administrative
Fixed assets
Depreciation of fixed assets	3,937,000	1,156,000	1,107,000
Intangible assets other than goodwill
Amortization of intangible assets	$ 296,000	56,000	445,000
Building
Fixed assets
Estimated useful life	40 years
Land improvements
Fixed assets
Estimated useful life	20 years
Building machinery and equipment | Minimum
Fixed assets
Estimated useful life	15 years
Building machinery and equipment | Maximum
Fixed assets
Estimated useful life	20 years
Furniture and equipment | Minimum
Fixed assets
Estimated useful life	5 years
Furniture and equipment | Maximum
Fixed assets
Estimated useful life	7 years
Computer hardware | Minimum
Fixed assets
Estimated useful life	3 years
Computer hardware | Maximum
Fixed assets
Estimated useful life	4 years
Computer software | Minimum
Fixed assets
Estimated useful life	2 years
Computer software | Maximum
Fixed assets
Estimated useful life	4 years
Internal-use software and website development
Fixed assets
Capitalized costs	$ 9,600,000	15,900,000	18,100,000
Amortization of capitalized costs	$ 15,900,000	17,100,000	14,400,000
Internal-use software and website development | Minimum
Fixed assets
Estimated useful life	2 years
Internal-use software and website development | Maximum
Fixed assets
Estimated useful life	3 years
Cirrus Technologies LLC
Intangible assets other than goodwill
Accumulated amortization of intangible assets	$ (9,228,000)
Amortization of intangible assets	$ (3,900,000)	$ (3,900,000)	$ (1,500,000)