Marketable Investment Securities (Tables)

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of marketable investment securities

Our marketable investment securities portfolio consists of various debt and equity instruments summarized in the table below (amounts in thousands):

	As of
	June 30, 2019		December 31, 2018
Marketable investment securities:
Debt securities:
Corporate bonds	$	891,695	$	1,735,653
Other debt securities	277,568		464,997
Total debt securities	1,169,263		2,200,650
Equity securities	52,753		90,976
Total marketable investment securities	1,222,016		2,291,626
Less: Restricted marketable investment securities	18,708		9,474
Total marketable investment securities	$	1,203,308	$	2,282,152

Schedule of unrealized gains (losses) on available-for-sale securities

A summary of our available-for-sale debt securities, exclusive of securities where we have elected the fair value option, is presented in the table below (amounts in thousands):

	Amortized		Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
As of June 30, 2019
Corporate bonds	$	883,857	$	1,263	$	(141	)	$	884,979
Other debt securities	277,539		29		—			277,568
Total available-for-sale debt securities	$	1,161,396	$	1,292	$	(141	)	$	1,162,547
As of December 31, 2018
Corporate bonds	$	1,689,093	$	318	$	(1,896	)	$	1,687,515
Other debt securities	464,993		7		(3		)	464,997
Total available-for-sale debt securities	$	2,154,086	$	325	$	(1,899	)	$	2,152,512

Schedule of fair value measurements

Our marketable investment securities are measured at fair value on a recurring basis as summarized in the table below (amounts in thousands). Certain of our investments in debt and equity instruments have historically experienced and are likely to continue experiencing volatility. As of June 30, 2019 and December 31, 2018, we did not have investments that were categorized within Level 3 of the fair value hierarchy.

	As of
	June 30, 2019						December 31, 2018
	Level 1		Level 2		Total		Level 1		Level 2		Total
Debt securities:
Corporate bonds	$	—	$	891,695	$	891,695	$	—	$	1,735,653	$	1,735,653
Other debt securities	18,708		258,860		277,568		9,474		455,523		464,997
Total debt securities	18,708		1,150,555		1,169,263		9,474		2,191,176		2,200,650
Equity securities	46,127		6,626		52,753		85,298		5,678		90,976
Total marketable investment securities	$	64,835	$	1,157,181	$	1,222,016	$	94,772	$	2,196,854	$	2,291,626