Financial Instruments and Investments Unrealized Gains and Losses on Equity Securities (Details) - Equity Securities $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
Unrealized Gains and losses recognized [Line Items]
Net gains and (losses) recognized on equity securities	$ (11,522)
Less: Net gains and (losses) recognized on equity securities sold	7,079
Unrealized gains and (losses) recognized on equity securities still held at reporting date	$ (18,601)

Amount of unrealized gain (loss) recognized in the income statement on unsold other securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration