Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ (73,324)	$ 79,812	$ 33,291
Adjustments to reconcile net income (loss) to cash provided by operating activities, net of the effects of acquisitions:
Depreciation and amortization	137,878	153,503	160,863
Loss on divestiture of business	7,660	0	0
Loss on disposal of fixed assets	260	481	271
Deal related compensation expense and accretion charges	102	153	153
Share-based compensation expense associated with equity awards	56,328	47,317	39,189
Net change in fair value of contingent and contractual liabilities	1,614	0	0
Accretion of contingent consideration	(119)	0	0
Impairment charge	35,871	0	0
Deferred income taxes	(33,442)	(127,784)	(11,008)
Other (gains) losses	(152)	18	(111)
Changes in assets and liabilities
Accounts receivable and unbilled costs	(22,180)	84,952	(48,080)
Due from related party	172	443	25,055
Inventories	5,321	1,006	12,456
Prepaid expenses and other assets	3,034	20,147	(24,751)
Accounts payable	(3,876)	(8,929)	405
Accrued compensation and other expenses	19,964	(17,718)	6,785
Due to related party	234	(75)	(2,792)
Income taxes payable	(639)	(2,734)	1,963
Deferred revenue	15,132	(8,138)	33,075
Net cash provided by operating activities	149,838	222,454	226,764
Cash flows from investing activities:
Purchase of marketable securities	(229,769)	(114,178)	(199,841)
Proceeds from maturity of marketable securities	230,433	196,041	181,321
Purchase of fixed assets	(23,392)	(15,913)	(29,696)
Purchase of intangible assets	0	(544)	(1,031)
Payments related to the divestiture of business	(3,293)	0	0
Acquisition of businesses, net of cash acquired	0	(8,334)	(4,606)
(Increase) decrease in deposits	(97)	(330)	129
Contingent purchase consideration	0	523	660
Collection of contingently returnable consideration	0	0	12,864
Capitalized software development costs	(134)	(137)	(1,421)
Net cash (used in) provided by investing activities	(26,252)	57,128	(41,621)
Cash flows from financing activities:
Issuance of common stock under stock plans	3	1	2
Payment of contingent consideration	(2,851)	(660)	0
Treasury stock repurchases, including accelerated share repurchases	(14,468)	(501,324)	(79,996)
Tax withholding on restricted stock units	(11,969)	(13,598)	(9,559)
Proceeds from issuance of long-term debt, net of issuance costs	0	294,619	0
Repayment of long-term debt	(50,000)	0	0
Net cash used in financing activities	(79,285)	(220,962)	(89,553)
Effect of exchange rate changes on cash and cash equivalents	(5,212)	6,385	(761)
Net increase in cash and cash equivalents	39,089	65,005	94,829
Cash and cash equivalents, beginning of year	370,731	305,726	210,897
Cash and cash equivalents, end of year	409,820	370,731	305,726
Supplemental disclosures of cash flow information:
Cash paid for interest	23,281	9,604	6,442
Cash paid for income taxes	13,381	18,216	49,290
Non-cash transactions:
Transfers of inventory to fixed assets	2,152	5,556	4,928
Additions to property, plant and equipment included in accounts payable	455	1,379	1,241
Issuance of common stock under employee stock purchase plans	15,074	17,849	15,697
Contingent consideration related to acquisition, included in accrued other	0	523	660
Tenant improvement allowance	10,171	2,104	0
Initial fair value of contingent consideration received as partial consideration for divestiture of business	$ 2,257	$ 0	$ 0