6. Restricted Cash and Investments (Tables)

6 Months Ended

Jun. 30, 2016

Restricted Cash and Investments [Abstract]

Restricted cash and investments consisted of the following at June 30, 2016 and December 31, 2015 (in thousands):



	June 30, 2016		December 31, 2015
Restricted cash	$	4,830	$	7,764
Restricted investments	409,189		326,114
Total restricted cash and investments (1)	$	414,019	$	333,878


(1)	There was an additional $40.5 million and $72.5 million of restricted cash included within prepaid expenses and other current assets at June 30, 2016 and December 31, 2015, respectively.

Restricted Available For Sale Securities

The following tables summarize the unrealized gains and losses related to our restricted investments, by major security type, as of June 30, 2016 and December 31, 2015 (in thousands):



	As of June 30, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Foreign government obligations	$	116,826	$	90,112	$	—	$	206,938
U.S. government obligations	169,847		32,404		—		202,251
Total	$	286,673	$	122,516	$	—	$	409,189



	As of December 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Foreign government obligations	$	177,507	$	75,670	$	—	$	253,177
U.S. government obligations	61,228		11,709		—		72,937
Total	$	238,735	$	87,379	$	—	$	326,114