Marketable Investment Securities (Tables)

3 Months Ended

Mar. 31, 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. Certain of our investments in debt and equity instruments have historically experienced and are likely to continue experiencing volatility.

	As of
	March 31, 2019		December 31, 2018
	(In thousands)
Marketable investment securities:
Debt securities:
Corporate bonds	$	1,470,693	$	1,735,653
Other debt securities	400,125		464,997
Total debt securities	1,870,818		2,200,650
Equity securities	64,887		90,976
Total marketable investment securities	1,935,705		2,291,626
Less: Restricted marketable investment securities	10,597		9,474
Total marketable investment securities	$	1,925,108	$	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.

	Amortized		Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
	(In thousands)
As of March 31, 2019
Corporate bonds	$	1,416,632	$	1,287	$	(120	)	$	1,417,799
Other debt securities	400,129		13		(17		)	400,125
Total available-for-sale debt securities	$	1,816,761	$	1,300	$	(137	)	$	1,817,924
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. As of March 31, 2019 and December 31, 2018, we did not have investments that were categorized within Level 3 of the fair value hierarchy.

	As of
	March 31, 2019						December 31, 2018
	Level 1		Level 2		Total		Level 1		Level 2		Total
	(In thousands)
Debt securities:
Corporate bonds	$	—	$	1,470,693	$	1,470,693	$	—	$	1,735,653	$	1,735,653
Other	10,597		389,528		400,125		9,474		455,523		464,997
Total debt securities	10,597		1,860,221		1,870,818		9,474		2,191,176		2,200,650
Equity securities	58,400		6,487		64,887		85,298		5,678		90,976
Total marketable investment securities	$	68,997	$	1,866,708	$	1,935,705	$	94,772	$	2,196,854	$	2,291,626