Investments Total Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments [Abstract]
Equity method investments	$ 1,254,198	$ 1,642,117
Cost method investments	27,593	26,748
Marketable equity securities	0	6,018
Investments	$ 1,281,791	$ 1,674,883

Amount of equity securities categorized neither as held-to-maturity nor as trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

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