CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 63,082	$ 55,412
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15,624	14,838
Amortization of debt issuance costs	1,087	845
Stock-based compensation	25,005	24,599
Excess tax benefit from stock-based compensation	(1,019)	(3,300)
Deferred income taxes	(753)	2,185
Provision for excess and obsolete inventories	1,292	1,319
Restructuring charges (credits)	(1,350)	8,433
Cash payments for restructuring charges	(3,793)	0
Other operating activities	633	5,896
Changes in assets and liabilities:
Accounts receivable, net	(13,448)	1,279
Inventory, net	(5,990)	(352)
Current and other assets	(2,346)	(264)
Accounts payable	3,626	5,744
Accrued liabilities	6,191	(3,841)
Income taxes	(1,141)	(8,770)
Cash provided by operating activities	86,700	104,023
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from sales of investments	143,631	56,890
Proceeds from maturities of investments	97,253	51,895
Purchase of investments	(247,491)	(206,110)
Capital expenditures	(19,603)	(20,977)
Cash used for investing activities	(26,210)	(118,302)
CASH FLOWS FROM FINANCING ACTIVITIES
Repurchase of common stock	(34,236)	(482,776)
Employees' tax withheld and paid for restricted stock and restricted stock units	(9,444)	(10,804)
Proceeds from issuances under stock-based compensation plans	6,516	9,854
Proceeds from revolving line of credit	0	155,749
Repayments of revolving line of credit	0	(190,249)
Proceeds from bonds issuance, net of issuance costs	0	488,401
Payment of cash dividends	(14,947)	(16,034)
Excess tax benefit from stock-based compensation	1,019	3,300
Other financing activity	761	0
Cash used for financing activities	(50,331)	(42,559)
Effect of exchange rate changes on cash and cash equivalents	(2,964)	(921)
Net increase (decrease) in cash and cash equivalents	7,195	(57,759)
Cash and cash equivalents at beginning of period	235,266	276,850
Cash and cash equivalents at end of period	$ 242,461	$ 219,091