Fair Value Measurements Equity Securities Without Readily Determinable Fair Values (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Equity Securities Without Readily Determinable Fair Value Amount [Roll Forward]
Carrying value as of December 31, 2018	$ 0
Upward carrying value changes	13,444	$ 0
Carrying value as of June 30, 2019	13,000
Fair Value, Inputs, Level 3
Equity Securities Without Readily Determinable Fair Value Amount [Roll Forward]
Carrying value as of December 31, 2018	0
Upward carrying value changes	13,444
Carrying value as of June 30, 2019	13,444
Cumulative upward carrying value changes between January 1, 2018 and June 30, 2019	13,444
Cumulative downward carrying value changes/impairment between January 1, 2018 and June 30, 2019	$ 0

Equity Securities Without Readily Determinable Fair Value Amount [Roll Forward]

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- Definition

Amount of investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714

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- Definition

Amount of cumulative loss from downward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714

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- Definition

Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714

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- Definition

Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714

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