Marketable Securities

12 Months Ended

Dec. 31, 2017

3 Marketable Securities

The Company’s marketable securities within cash equivalents and investments included in the consolidated balance sheets are detailed as follows (in thousands):

		December 31, 2017
		Amortized		Unrealized		Unrealized		Fair
		Cost		Gain		Loss		Value
U.S. Treasury securities		$	593,599	$	82	$	(1,693)	$	591,988
Foreign government securities			6,982		-		(30)		6,952
Corporate debt securities			1,977,329		897		(3,066)		1,975,160
Time deposits			371,515		-		(4)		371,511
Equity securities			77		70		-		147
	Total	$	2,949,502	$	1,049	$	(4,793)	$	2,945,758

Amounts included in:
	Cash equivalents	$	194,377	$	-	$	(1)	$	194,376
	Investments		2,755,125		1,049		(4,792)		2,751,382
	Total	$	2,949,502	$	1,049	$	(4,793)	$	2,945,758

		December 31, 2016
		Amortized		Unrealized		Unrealized		Fair
		Cost		Gain		Loss		Value
U.S. Treasury securities		$	570,695	$	253	$	(635)	$	570,313
Foreign government securities			17,999		-		(8)		17,991
Corporate debt securities			1,645,468		496		(2,126)		1,643,838
Time deposits			199,906		-		-		199,906
Equity securities			77		70		-		147
	Total	$	2,434,145	$	819	$	(2,769)	$	2,432,195

Amounts included in:
	Cash equivalents	$	124,793	$	1	$	-	$	124,794
	Investments		2,309,352		818		(2,769)		2,307,401
	Total	$	2,434,145	$	819	$	(2,769)	$	2,432,195

The estimated fair value of marketable debt securities by maturity date is as follows (in thousands):

		December 31, 2017		December 31, 2016
Due in one year or less		$	1,722,553	$	1,388,537
Due after one year through three years			851,547		843,605
	Total	$	2,574,100	$	2,232,142

Realized gains and losses on sales of investments were not material in 2017, 2016 and 2015.