Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Unrecognized tax benefits	$ 2,700,000		$ 2,700,000
Unrecognized tax benefits would impact the effective tax rate	2,600,000		2,600,000
Interest accrued	300,000		$ 300,000
Effective tax rate from operations			36.00%	22.40%
(Benefit from) provision for income taxes	(8,804,000)	$ (291,000)	$ (5,735,000)	$ 6,419,000
Effective U.S corporate tax rate			21.00%				35.00%
Provision for transition tax						$ 37,200,000	$ 40,300,000
Measurement period adjustment to reduce transition tax						$ (3,100,000)
Transition tax, unpaid	28,000,000.0		$ 28,000,000.0
Transition Tax over an eight-year period beginning			2018
Digital asset impairment losses	44,242,000	$ 0	$ 44,242,000	$ 0
Tax benefit of impairment losses	12,800,000		12,800,000
Other Long-term Liabilities
Income Taxes
Transition tax, unpaid	25,100,000		25,100,000
Accounts Payable, Accrued Expenses and Operating Lease Liabilities
Income Taxes
Transition tax, unpaid	3,000,000.0		3,000,000.0
U.S
Income Taxes
Cash and cash equivalents and short-term investments	19,000,000.0		$ 19,000,000.0		$ 289,400,000
U.S | Earliest Tax Year
Income Taxes
Tax years subject to examination			2016
Italy | Earliest Tax Year
Income Taxes
Tax years subject to examination			2016
Poland | Earliest Tax Year
Income Taxes
Tax years subject to examination			2015
Spain | Earliest Tax Year
Income Taxes
Tax years subject to examination			2016
United Kingdom | Earliest Tax Year
Income Taxes
Tax years subject to examination			2018
Germany | Earliest Tax Year
Income Taxes
Tax years subject to examination			2016
Foreign
Income Taxes
Cash and cash equivalents and short-term investments	33,700,000		$ 33,700,000		276,200,000
Foreign earnings repatriated			186,600,000		$ 151,300,000
Undistributed foreign earnings	$ 94,800		$ 94,800