Other Assets - Notes receivable due from equity instruments (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Total notes receivable due from equity investments		$ 277,635	$ 314,323
Less-current portion	[1]	89,632	38,658
Long-term portion	[2]	$ 188,003	$ 275,665

[1] Included within Trade and other receivables, net in our consolidated balance sheets.

[2] Included within Other assets in our consolidated balance sheets.