Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Investments Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s investments at December 31, 2016 and 2015 measured at fair value on a recurring basis (in thousands):

	December 31, 2016							December 31, 2015
			Gross							Gross
			Unrealized							Unrealized
			Gains			Recorded				Gains		Recorded
	Cost		(Losses)			Basis		Cost		(Losses)		Basis
Current:
Cash equivalents:
Money market funds	$	1,943	$	—		$	1,943	$	21,312	$	—	$	21,312

Investments:
Certificates of deposit	$	4,737	$	—		$	4,737	$	—	$	—	$	—
Municipal bonds		713		1			714		—		—		—
Corporate bonds		225		(1	)		224		—		—		—

Restricted cash and investments:
Money market funds	$	48,557	$	—		$	48,557	$	76,023	$	—	$	76,023
Certificates of deposit		—		—			—		10,000		—		10,000
Total current investments	$	56,175	$	—		$	56,175	$	107,335	$	—	$	107,335

	December 31, 2016							December 31, 2015
			Gross							Gross
			Unrealized							Unrealized
			Gains			Recorded				Gains			Recorded
	Cost		(Losses)			Basis		Cost		(Losses)			Basis
Long term:
Investments:
Corporate bonds	$	567	$	(1	)	$	566	$	2,970	$	(24	)	$	2,946
Municipal bonds		76		—			76		3,135		(3	)		3,132
Money market funds		—		—			—		4		0			4

Restricted cash and investments ⁽¹⁾
Money market funds	$	236,036	$	—		$	236,036	$	175,869	$	—		$	175,869
Certificates of deposit		6,047		—			6,047		496		(1	)		495
Corporate bonds		2,886		2			2,888		2,996		(24	)		2,972
Municipal bonds		2,069		(6	)		2,063		3,613		(1	)		3,612
U.S. treasuries		834		—			834		4,752		1			4,753
Total long term investments		248,515		(5	)		248,510		193,835		(52	)		193,783
Total investments	$	304,690	$	(5	)	$	304,685	$	301,170	$	(52	)	$	301,118

Included in restricted cash and investments within the balance sheet as of December 31, 2016 is restricted cash and long term workers' compensation deposits of $4.8 million, which is excluded from the table above.

Summary of Assets Measured at Fair Value on Recurring Basis

The following table summarizes the Company's financial assets measured at fair value on a recurring basis by fair value hierarchy level (in thousands):

	December 31, 2016										December 31, 2015
	Total											Total
	Recorded											Recorded
	Basis		Level 1		Level 2		Level 3		Other ⁽¹⁾			Basis		Level 1		Level 2		Level 3		Other ⁽¹⁾
Cash Equivalents:
Money market funds	$	1,943	$	—	$	—	$	—	$	1,943		$	21,312	$	—	$	—	$	—	$	21,312

Investments:
Certificates of deposit	$	4,737	$	—	$	4,737	$	—	$	—		$	—	$	—	$	—	$	—	$	—
Municipal bonds		790		—		790		—		—			3,132		241		2,891		—		—
Corporate bonds		790		—		790		—		—			2,946		2,291		655		—		—
Money market funds		—		—		—		—		—			4		—		—		—		4

Restricted Cash and Investments: ⁽²⁾
Money market funds	$	284,593	$	—	$	—	$	—	$	284,593		$	251,892	$	—	$	—	$	—	$	251,892
Certificates of deposit		6,047		—		6,047		—		—			10,495		—		10,495		—		—
Corporate bonds		2,888		—		2,888		—		—			2,972		2,285		687		—		—
Municipal bonds		2,063		—		2,063		—		—			3,612		389		3,223		—		—
U.S. treasuries		834		—		834		—		—			4,753		4,753		—		—		—
Total Investments	$	304,685	$	—	$	18,149	$	—	$	286,536		$	301,118	$	9,959	$	17,951	$	—	$	273,208

(1)

In accordance with ASU 2015-07, investments in money market funds measured at fair value using the NAV per share practical expedient are not subject to hierarchy level classification disclosure. The Company invests in money market funds that seek to maintain a stable net asset value. These investments include commingled funds that comprise high-quality short-term securities representing liquid debt and monetary instruments where the redemption value is likely to be the fair value. Redemption is permitted daily without written notice.

(2)	Included in restricted cash and investments within the balance sheet as of December 31, 2016 is restricted cash and long term workers' compensation deposits of $4.8 million, which is excluded from the table above.