CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 395,281	$ 127,389	$ 336,705
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	189,139	204,097	99,424
Deferred income taxes	5,321	(28,368)	21,954
Share-based compensation expense related to equity incentive plans	53,787	52,069	38,289
Excess tax benefit from share-based compensation	(1,411)	(297)	(576)
Convertible debt derivatives - revaluation and amortization	(482)	138	204
Amortization of debt discount on convertible debentures	8,970	8,197	7,512
Amortization of debt issuance costs	1,959	217	219
Losses on equity method investments	177	617	195
Losses (gains) on sale of assets	244	(256)	(411)
Loss on write-down of fixed assets	0	400	0
Impairment of intangible assets	350	0	0
Amortization of premium on available-for-sale investments	10,754	13,186	15,520
Unrealized impairment loss on available-for-sale investments	0	413	2,158
Special (income) charges	(459)	4,400	(1,000)
Gain on shares of acquired company	(2,438)	0	0
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(12,508)	386	11,845
(Increase) decrease in inventories	(18,500)	65,867	(35,240)
Increase (decrease) in deferred income on shipments to distributors	8,846	18,867	(31,335)
Decrease in accounts payable and accrued liabilities	(11,633)	(40,914)	(61,455)
Change in other assets and liabilities	49,167	32,957	7,970
Net cash provided by operating activities	676,564	459,365	411,978
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,337,482)	(998,977)	(1,149,145)
Sales and maturities of available-for-sale investments	951,296	856,579	983,500
Acquisition of SMSC, net of cash acquired	0	(731,746)	0
Other business acquisitions, net of cash acquired	(11,187)	(20,556)	(38,580)
Investments in other assets	(9,069)	(4,730)	(5,818)
Proceeds from sale of assets	16,235	306	411
Capital expenditures	(113,072)	(50,818)	(62,370)
Net cash used in investing activities	(503,279)	(949,942)	(272,002)
Cash flows from financing activities:
Repayments of revolving loan under previous credit facility	(650,000)	(761,000)	0
Repayments of revolving loan under new credit facility	(453,500)	0	0
Proceeds from borrowings on revolving loan under previous credit facility	30,000	1,381,000	0
Proceeds from borrowings on revolving loan under new credit facility	753,500	0	0
Proceeds from issuance of long-term borrowings	350,000	0	0
Deferred financing costs	(7,515)	0	0
Payment of cash dividends	(281,204)	(273,822)	(266,178)
Proceeds from sale of common stock	37,446	35,695	57,457
Contingent consideration payment	(14,700)	0	0
Capital lease payments	(454)	0	0
Excess tax benefit from share-based compensation	1,411	297	576
Net cash (used in) provided by financing activities	(235,016)	382,170	(208,145)
Effect of foreign exchange rate changes on cash and cash equivalents	0	986	0
Net decrease in cash and cash equivalents	(61,731)	(107,421)	(68,169)
Cash and cash equivalents at beginning of period	528,334	635,755	703,924
Cash and cash equivalents at end of period	$ 466,603	$ 528,334	$ 635,755