Fair Value Measurements (Tables)

12 Months Ended

Mar. 31, 2017

Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]

Fair Value, Assets and Liabilities Measured on Recurring Basis

Assets measured at fair value on a recurring basis at March 31, 2017 are as follows (amounts in thousands):

	Quoted Prices in Active Markets for  Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Total Balance
Assets
Cash and cash equivalents:
Money market mutual funds	$	343,815	$	—	$	343,815
Deposit accounts	—		564,869		564,869
Short-term investments:
Marketable equity securities	1,586		—		1,586
Corporate bonds and debt	—		165,207		165,207
Government agency bonds	—		161,973		161,973
Municipal bonds - tax exempt	—		55,279		55,279
Municipal bonds	—		10,043		10,043
Long-term investments:
Corporate bonds and debt	—		42,565		42,565
Government agency bonds	—		64,892		64,892
Total assets measured at fair value	$	345,401	$	1,064,828	$	1,410,229

Assets measured at fair value on a recurring basis at March 31, 2016 are as follows (amounts in thousands):

	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Total Balance
Assets
Cash and cash equivalents:
Money market mutual funds	$	1,787,446	$	—	$	1,787,446
Deposit accounts	—		305,305		305,305
Short-term investments:
Marketable equity securities	2,203		—		2,203
Corporate bonds and debt	—		1,000		1,000
Government agency bonds	—		350,081		350,081
Long-term investments:
Government agency bonds	—		118,549		118,549
Total assets measured at fair value	$	1,789,649	$	774,935	$	2,564,584

Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

The following table presents a reconciliation for all assets measured at fair value on a recurring basis, excluding accrued interest components, using significant unobservable inputs (Level 3) for the year ended March 31, 2016 (amounts in thousands):

Year ended March 31, 2016	Auction Rate Securities			Corporate Debt			Total Gains (Losses)
Balance at March 31, 2015	$	9,825		$	6,190		$	—
Total gains (losses) (realized):
Included in earnings	2,780			(3,995		)	(1,215		)
Purchases, sales, issuances, and settlements, net	(12,605		)	—			—
Transfers out of Level 3	—			(2,195		)	—
Balance at March 31, 2016	$	—		$	—		$	(1,215	)