Fair Value Measurements (Tables)

12 Months Ended

Mar. 31, 2015

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

Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Assets measured at fair value on a recurring basis at March 31, 2015 are as follows (amounts in thousands):

	Quoted Prices in Active Markets for  Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant  Unobservable Inputs (Level 3)		Total Balance
Assets
Money market mutual funds	$	279,833	$	—	$	—	$	279,833
Marketable equity securities	13,166		—		—		13,166
Corporate bonds and debt	—		920,739		6,190		926,929
Time deposits (1)	—		506		—		506
Government agency bonds	—		742,256		—		742,256
Deposit accounts	—		327,982		—		327,982
Municipal bonds	—		41,698		—		41,698
Auction rate securities	—		—		9,825		9,825
Derivative assets	—		8,928		—		8,928
Total assets measured at fair value	$	292,999	$	2,042,109	$	16,015	$	2,351,123

⁽¹⁾ Time deposits in various financial institutions with maturities greater than three months that will mature within one year.

Assets measured at fair value on a recurring basis at March 31, 2014 are as follows (amounts in thousands):

	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Balance
Assets
Money market mutual funds	$	192,159	$	—	$	—	$	192,159
Corporate bonds and debt	—		937,776		6,190		943,966
Government agency bonds	—		681,394		—		681,394
Deposit accounts	—		274,444		—		274,444
Municipal bonds	—		41,709		—		41,709
Auction rate securities	—		—		9,825		9,825
Total assets measured at fair value	$	192,159	$	1,935,323	$	16,015	$	2,143,497

Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following table presents a reconciliation for all assets and liabilities measured at fair value on a recurring basis, excluding accrued interest components, using significant unobservable inputs (Level 3) for the year ended March 31, 2014. There were no changes in the fair value of these assets measured on a recurring basis during fiscal 2015 (amounts in thousands):

Year ended March 31, 2014	Auction Rate Securities			Corporate Debt		Contingent Consideration			Total Losses
Balance at March 31, 2013	$	33,791		$	6,190	$	(19,100	)	$	—
Total gains (losses) (realized and unrealized):
Included in earnings	1,101			—		(1,370		)	(269		)
Included in other comprehensive income	(332		)	—		—			(332		)
Purchases, sales, issuances, and settlements, net	(24,735		)	—		20,470			—
Balance at March 31, 2014	$	9,825		$	6,190	$	—		$	(601	)

Fair Value, by Balance Sheet Grouping

Assets measured at fair value on a recurring basis are presented/classified on the consolidated balance sheets at March 31, 2015 as follows (amounts in thousands):

	Quoted Prices  in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Balance
Assets
Cash and cash equivalents	$	279,833	$	327,982	$	—	$	607,815
Short-term investments	13,166		1,337,888		—		1,351,054
Long-term investments	—		367,311		16,015		383,326
Other assets	—		8,928		—		8,928
Total assets measured at fair value	$	292,999	$	2,042,109	$	16,015	$	2,351,123

Assets measured at fair value on a recurring basis are presented/classified in the consolidated balance sheets at March 31, 2014 as follows (amounts in thousands):

	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs  (Level 3)		Total Balance
Assets
Cash and cash equivalents	$	192,159	$	274,444	$	—	$	466,603
Short-term investments	—		878,182		—		878,182
Long-term investments	—		782,697		16,015		798,712
Total assets measured at fair value	$	192,159	$	1,935,323	$	16,015	$	2,143,497