Accounting Policies (Details) - USD ($) $ in Thousands	Jan. 01, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit		$ (224,299)	$ (272,860)	$ (321,281)	$ (369,669)	$ (422,092)	$ (405,143)	$ (450,507)	$ (245,059)
Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Senior convertible debt	$ 65,600
Common Stock and Additional Paid-in Capital | Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit	75,300
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit		$ 1,497,370	$ 1,439,366	$ 1,380,470	$ 1,324,840	$ 1,254,670	$ 1,194,581	$ 1,141,257	$ 1,115,457
Accumulated Deficit | Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit	$ 9,700