Investments (Tables)

3 Months Ended

Mar. 31, 2018

Investments [Abstract]

Investments in Marketable Equity Securities

Investments in marketable equity securities comprised the following:

	As of
	March 31, 2018		December 31, 2017
(in thousands)
Total cost	$	247,321	$	269,343
Gross unrealized gains	224,382		266,972
Total Fair Value	$	471,703	$	536,315