The following tables summarize the Company’s cash and available-for-sale securities’ amortized cost, gross unrealized gains, gross unrealized losses, and fair value by significant investment category recorded as cash and cash equivalents, short-term, or long-term investments as of December 31, 2018 and March 31, 2018 (in thousands):



December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash & Cash Equivalents		Short-term investments (due in 1 year or less)
Cash	$	328,156	$	—	$	—		$	328,156	$	328,156	$	—
Level 1:
Mutual Funds	14,753		—		(1,331		)	13,422		—		13,422
Subtotal	14,753		—		(1,331		)	13,422		—		13,422

Total cash, cash equivalents and investments measured at fair value	$	342,909	$	—	$	(1,331	)	$	341,578	$	328,156	$	13,422



March 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash & Cash Equivalents		Short-term investments (due in 1 year or less)
Cash	$	308,734	$	—	$	—		$	308,734	$	308,734	$	—
Level 1:
Mutual Funds	13,336		186		(67		)	13,455		—		13,455
US Treasury Notes	129,373		7		(60		)	129,320		30,178		99,142
Money Market Funds	344		—		—			344		344		—
Subtotal	143,053		193		(127		)	143,119		30,522		112,597
Level 2:
Government Agency Securities	46,354		—		(56		)	46,298		6,978		39,320
Municipal Bonds	3,591		—		—			3,591		3,591		—
Commercial Paper	84,512		—		—			84,512		40,836		43,676
Corporate Bonds	54,701		—		(212		)	54,489		—		54,489
Certificates of Deposits ("CDs")	19,231		—		—			19,231		—		19,231
Subtotal	208,389		—		(268		)	208,121		51,405		156,716

Total cash, cash equivalents and investments measured at fair value	$	660,176	$	193	$	(395	)	$	659,974	$	390,661	$	269,313