Financial Instruments

12 Months Ended

Dec. 31, 2016

Investments All Other Investments [Abstract]

Financial Instruments

4. Financial Instruments

Cash equivalents, restricted cash and short-term and long-term investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):

December 31, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	10,156	$	—	$	—		$	10,156
Restricted cash (money market funds)		19,593		—		—			19,593
U.S. government agency securities		6,802		—		(2	)		6,800
Total financial assets	$	36,551	$	—	$	(2	)	$	36,549
Classified as:
Cash and cash equivalents								$	10,156
Restricted cash (money market funds)									19,593
Short-term investments									6,800
								$	36,549

December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	28,927	$	—	$	—		$	28,927
Restricted cash (money market funds)		33,919		—		—			33,919
Municipal bonds		295		1		—			296
Corporate notes		3,106		1		(1	)		3,106
Total financial assets	$	66,247	$	2	$	(1	)	$	66,248
Classified as:
Cash and cash equivalents								$	28,927
Restricted cash (money market funds)									33,919
Short-term investments									3,402
								$	66,248

As of December 31, 2016, the remaining contractual maturities of available-for-sale securities was less than one year. There have been no significant realized gains or losses on available-for-sale securities for the periods presented. The carrying amounts of cash, accounts receivable and accounts payable approximate fair values due to the short-term maturity of these instruments.