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Cash, Cash Equivalents, Short-term and Long-term Investments, Fair Value

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Cash, Cash Equivalents, Short-term and Long-term Investments, Gross Unrealized Gain

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Cash, Cash Equivalents, Short-term and Long-term Investments, Gross Unrealized Loss

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Contractual interest rate for funds borrowed, under the debt agreement.

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CASH, CASH EQUIVALENTS, AND INVESTMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	May 31, 2015
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	$ 328,156	$ 390,661	$ 280,293	$ 301,970
Short-term investments (due in 1 year or less)	13,422	269,313
Total cash, cash equivalents and investments measured at fair value, amortized cost	342,909	660,176
Total cash, cash equivalents and investments measured at fair value, gross unrealized gains	0	193
Total cash, cash equivalents and investments measured at fair value, gross unrealized losses	(1,331)	(395)
Total cash, cash equivalents and investments measured at fair value, fair value	341,578	659,974
Cash [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	328,156	308,734
Level 1 [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	0	30,522
Available-for-sale Securities, amortized cost basis	14,753	143,053
Available-for-sale Securities, gross unrealized gains	0	193
Available-for-sale Securities, gross unrealized losses	(1,331)	(127)
Available-for-sale Securities, fair value	13,422	143,119
Short-term investments (due in 1 year or less)	13,422	112,597
Level 1 [Member] \| Mutual Funds [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	0	0
Available-for-sale Securities, amortized cost basis	14,753	13,336
Available-for-sale Securities, gross unrealized gains	0	186
Available-for-sale Securities, gross unrealized losses	(1,331)	(67)
Available-for-sale Securities, fair value	13,422	13,455
Short-term investments (due in 1 year or less)	$ 13,422	13,455
Level 1 [Member] \| US Treasury Notes [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		30,178
Available-for-sale Securities, amortized cost basis		129,373
Available-for-sale Securities, gross unrealized gains		7
Available-for-sale Securities, gross unrealized losses		(60)
Available-for-sale Securities, fair value		129,320
Short-term investments (due in 1 year or less)		99,142
Level 1 [Member] \| Money Market Funds [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		344
Available-for-sale Securities, amortized cost basis		344
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		0
Available-for-sale Securities, fair value		344
Level 2 [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		51,405
Available-for-sale Securities, amortized cost basis		208,389
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		(268)
Available-for-sale Securities, fair value		208,121
Short-term investments (due in 1 year or less)		156,716
Level 2 [Member] \| Government Agency Securities [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		6,978
Available-for-sale Securities, amortized cost basis		46,354
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		(56)
Available-for-sale Securities, fair value		46,298
Short-term investments (due in 1 year or less)		39,320
Level 2 [Member] \| Municipal Bonds [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		3,591
Available-for-sale Securities, amortized cost basis		3,591
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		0
Available-for-sale Securities, fair value		3,591
Short-term investments (due in 1 year or less)		0
Level 2 [Member] \| Commercial Paper [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		40,836
Available-for-sale Securities, amortized cost basis		84,512
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		0
Available-for-sale Securities, fair value		84,512
Short-term investments (due in 1 year or less)		43,676
Level 2 [Member] \| Corporate Bonds [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		0
Available-for-sale Securities, amortized cost basis		54,701
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		(212)
Available-for-sale Securities, fair value		54,489
Short-term investments (due in 1 year or less)		54,489
Level 2 [Member] \| Certificates of Deposit [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents		0
Available-for-sale Securities, amortized cost basis		19,231
Available-for-sale Securities, gross unrealized gains		0
Available-for-sale Securities, gross unrealized losses		0
Available-for-sale Securities, fair value		19,231
Short-term investments (due in 1 year or less)		$ 19,231
5.50% Senior Notes [Member] \| Senior Notes [Member]
Schedule of Cash, Cash Equivalents and Investments [Line Items]
Stated interest rate of debt instrument	5.50%				5.50%