CASH, CASH EQUIVALENTS, AND INVESTMENTS

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 September 30, 2018 and March 31, 2018 (in thousands):



September 30, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash & Cash Equivalents		Short-term investments (due in 1 year or less)
Cash	$	291,086	$	—	$	—		$	291,086	$	291,086	$	—
Level 1:
Mutual Funds	14,129		635		(59		)	14,705		—		14,705
Subtotal	14,129		635		(59		)	14,705		—		14,705

Total cash, cash equivalents and investments measured at fair value	$	305,215	$	635	$	(59	)	$	305,791	$	291,086	$	14,705



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

As of September 30, 2018 and March 31, 2018, with the exception of assets related to the Company's deferred compensation plan, all of the Company's investments are classified as available-for-sale securities. The carrying value of available-for-sale securities included in cash equivalents approximates fair value because of the short maturity of those instruments. For more information regarding the Company's deferred compensation plan, refer to Note 5, Deferred Compensation.

The Company did not incur any material realized or unrealized gains or losses in the three and six months ended September 30, 2017 and 2018.

There were no transfers between fair value measurement levels during the three and six months ended September 30, 2017 and 2018.

All financial assets and liabilities are recognized or disclosed at fair value in the financial statements or the accompanying notes thereto. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1

The Company's Level 1 financial assets consist of Mutual Funds and US Treasury Notes. The fair value of Level 1 financial instruments is measured based on the quoted market price of identical securities.

Level 2

The Company's Level 2 financial assets and liabilities consist of derivative foreign currency contracts, interest rate swap and 5.50% Senior Notes. The fair value of Level 2 derivative foreign currency contracts and interest rate swap is determined using pricing models that use observable market inputs. For more information regarding the Company's derivative assets and liabilities, refer to Note 13, Derivatives. The fair value of Level 2 long-term debt and term loan facility are determined based on inputs that were observable in the market, including the trading price of the notes when available. For more information regarding the Company's 5.50% Senior Notes and term loan facility, refer to Note 8, Debt.

Level 3

The Company's revolving credit facility falls under the Level 3 hierarchy. The fair value of Level 3 revolving credit facility is determined based on inputs that were unobservable in the market. For more information regarding the Company's debt, refer to Note 8, Debt.