Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ (1,489,374)		$ (1,126,250)	$ (1,007,939)	$ (796,368)
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ (798,573)		$ (558,269)	$ (364,882)	$ (79,461)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	[1]		$ 1,310
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	[1]		$ 1,310

[1] (2) The cumulative adjustment relates to the adoption of ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments" ("ASU 2016-13") on January 1, 2020, for which the Company recorded an adjustment to Retained Earnings to reflect the increase in the Company's Allowance for Doubtful Accounts as a result of the use of the current expected credit loss model. See Notes 2 and 3 for further information.