CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	[1]	Mar. 31, 2018
Operating activities:
Net income	$ 179,948	$ 25,140		$ 277,007	$ 82,680
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization and impairment of software development costs and licenses				160,167	62,235
Depreciation				28,769	23,233
Amortization and impairment of intellectual property				17,785	26,470
Impairment of in-process research and development				0	11,257
Stock-based compensation				178,609	96,111
Amortization of discount on Convertible Notes				91	15,424
Gain on conversions of Convertible Notes				0	(4,855)
Amortization of debt issuance costs				88	554
Other, net				(4,091)	3,432
Changes in assets and liabilities, net of impact of adoption of Topic 606:
Accounts receivable				(525,981)	(206,084)
Inventory				(26,352)	(12,976)
Software development costs and licenses				(157,710)	(186,373)
Prepaid expenses and other assets				(142,918)	(39,133)
Deferred revenue				328,325	238,590
Deferred cost of goods sold				(37,281)	(33,578)
Accounts payable, accrued expenses and other liabilities				293,691	164,086
Net cash provided by operating activities				390,199	241,073
Investing activities:
Change in bank time deposits				64,101	10,000
Proceeds from available-for-sale securities				184,542	172,925
Purchases of available-for-sale securities				(179,570)	(282,596)
Purchases of fixed assets				(43,646)	(47,478)
Asset acquisition				0	(25,965)
Business acquisition				(3,149)	(9,401)
Net cash provided by (used in) investing activities				22,278	(182,515)
Financing activities:
Tax payment related to net share settlements on restricted stock awards				(85,837)	(94,930)
Repurchase of common stock				(262,392)	(110,136)
Net cash used in financing activities				(348,229)	(205,066)
Effects of foreign currency exchange rates on cash and cash equivalents				(15,124)	14,555
Net change in cash, cash equivalents, and restricted cash				49,124	(131,953)
Cash, cash equivalents, and restricted cash, beginning of year				1,246,371	1,281,214		$ 1,281,214	[1]
Cash, cash equivalents, and restricted cash, end of period	$ 1,295,495	$ 1,149,261	[1]	$ 1,295,495	$ 1,149,261		$ 1,246,371

[1] Prior period amounts have been adjusted retrospectively to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. Refer to Note 1 for further discussion.