Marketable Investment Securities, Restricted Cash and Cash Equivalents, and Other Investment Securities - Changes in Level 3 Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Fair values transfers between Level 1 and Level 2
Fair value assets transfer from level 1 to level 2	$ 0	$ 0
Fair value liabilities transfer from level 1 to level 2	0	0
Fair value assets transfer from level 2 to level 1	0	0
Fair value liabilities transfer from level 2 to level 1	0	0
Investment Securities \| Level 3
Level 3 Investment Securities
Balance at the beginning of the year	6,363	142,140
Net realized and unrealized gains (losses) included in earnings		1,089
Net realized and unrealized gains (losses) included in other comprehensive income (loss)	547	(2,289)
Settlements	(189)	(134,577)
Balance at the end of the year	$ 6,721	$ 6,363

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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-Subparagraph (c)(1a)
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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
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-Section 50
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-Subparagraph (c)(2)
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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