Summary of Significant Accounting Policies - Significant Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred revenue
Beginning Balance	$ 300	$ 2,218
Cash receipts (Payments)	55,477	27,264
Less: Impact on Revenue	55,146	29,179
Other	0	(3)
Ending Balance	631	300
Payables to customers related to BTC
Beginning Balance	0	0
Cash receipts (Payments)	0	(150,776)
Less: Impact on Revenue	(255,193)	(144,944)
Other	0	5,832
Ending Balance	255,193	0
Total
Beginning Balance	300	2,218
Cash receipts (Payments)	55,477	(123,512)
Less: Impact on Revenue	(200,047)	(115,765)
Other	0	5,829
Ending Balance	$ 255,824	$ 300