Summary of Significant Accounting Policies - Fair Value Measurements (Details) - Fair value measured on recurring basis - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading securities	$ 11,067	$ 10,636
Derivative Liabilities	0	0
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading securities	256	256
Derivative Liabilities	34,497	49,703
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading securities	0	0
Derivative Liabilities	0	0
Estimate of Fair Value Measurement
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Trading securities	11,323	10,892
Derivative Liabilities	34,497	49,703
Money Market Funds \| QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	0	0
Money Market Funds \| SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	7,673	62,657
Money Market Funds \| SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	0	0
Money Market Funds \| Estimate of Fair Value Measurement
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	7,673	62,657
Bank Time Deposits \| QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	0	0
Bank Time Deposits \| SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	1,291	2,121
Bank Time Deposits \| SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	0	0
Bank Time Deposits \| Estimate of Fair Value Measurement
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money market funds	$ 1,291	$ 2,121

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

No definition available.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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