Significant Accounting Policies and Pronouncements (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Change in Accounting Estimate [Line Items]
Net unrealized gain on equity investments	$ (164,249)	$ (443,575)
ASU 2016-01
Change in Accounting Estimate [Line Items]
Net unrealized gain on equity investments	$ 0

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.

No definition available.

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