Short-Term Investments

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

Investments

Our investments in debt and equity securities classified as available-for-sale consisted of the following (in thousands):

	As of December 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Cash and Cash Equivalents		Short-Term Investments
Certificates of deposit	$	19,160	—		$	(36	)	$	19,124	$	—	$	19,124
Corporate notes and bonds	448,688		—		(1,421		)	447,267		—		447,267
U.S. Government agencies	302,152		2		(770		)	301,384		—		301,384
Total	$	770,000	$	2	$	(2,227	)	$	767,775	$	—	$	767,775

	As of December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Cash and Cash Equivalents		Short-Term Investments
Certificates of deposit	$	5,000	—		$	(6	)	$	4,994	$	—	$	4,994
Corporate notes and bonds	143,215		4		(235		)	142,984		—		142,984
U.S. Government agencies	121,021		1		(205		)	120,817		12,950		107,867
Total	$	269,236	$	5	$	(446	)	$	268,795	$	12,950	$	255,845

The following tables present the gross unrealized losses and related fair values of the above investments that have been in a continuous unrealized loss position (in thousands):

	As of December 31, 2015
	Less Than 12 Months					Greater Than 12 Months					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Certificates of deposit	$	18,404	$	(36	)	$	—	$	—		$	18,404	$	(36	)
Corporate notes and bonds	430,466		(1,407		)	16,801		(15		)	447,267		(1,422		)
U.S. Government agencies	266,541		(761		)	8,992		(8		)	275,533		(769		)
Total	$	715,411	$	(2,204	)	$	25,793	$	(23	)	$	741,204	$	(2,227	)

	As of December 31, 2014
	Less Than 12 Months					Greater Than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Certificates of deposit	$	3,793	$	(6	)	$	—	$	—	$	3,793	$	(6	)
Corporate notes and bonds	130,920		(235		)	—		—		130,920		(235		)
U.S. Government agencies	109,868		(205		)	—		—		109,868		(205		)
Total	$	244,581	$	(446	)	$	—	$	—	$	244,581	$	(446	)

Unrealized losses related to these investments are due to interest rate fluctuations as opposed to credit quality. In addition, we do not intend to sell, and it is not more likely than not that we would be required to sell, these investments before recovery of their cost basis. As a result, there is no other-than-temporary impairment for these investments as of December 31, 2015 and December 31, 2014.

The following table summarizes the contractual maturities of these investments at December 31, 2015 (in thousands):

	Amortized Cost		Fair Value
Due within one year	$	384,370	$	383,858
Due within one to two years	385,630		383,917
Total	$	770,000	$	767,775

All available-for-sale securities have been classified as current, based on management's intent and ability to use the funds in current operations.

During 2015, we invested in a privately held company, obtaining an initial 12.5% ownership interest. This investment is accounted for under the equity method based on our ability to exercise significant influence over operating and financial policies of the investee, and is classified within deposits and other long-term assets on our consolidated balance sheets. The carrying value of this investment was $1.8 million as of December 31, 2015.