CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$ 283,786	$ 67,699
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	143,704	140,468
Deferred income taxes	24,190	(9,981)
Share-based compensation expense related to equity incentive plans	41,375	38,713
Excess tax benefit from share-based compensation	0	(154)
Convertible debt derivatives - revaluation and amortization	(449)	253
Amortization of debt discount on convertible debentures	6,682	6,106
Amortization of debt issuance costs	1,416	164
Losses on equity method investments	211	382
Gain on sale of assets	0	(256)
Loss on write-down of fixed assets	0	400
Impairment of intangible assets	350	0
Amortization of premium on available-for-sale investments	8,067	10,304
Unrealized impairment loss on available-for-sale investments	0	412
Special income, net	(999)	0
Gain on shares of acquired company	(2,438)	0
Changes In Operating Assets And Liabilities
Decrease in accounts receivable	5,624	52,839
(Increase) decrease in inventories	(30,588)	47,146
Increase in deferred income on shipments to distributors	4,363	2,526
Decrease in accounts payable and accrued liabilities	(21,870)	(58,539)
Change in other assets and liabilities	9,799	33,000
Net cash provided by operating activities	473,223	331,482
Cash flows from investing activities
Purchases of available-for-sale investments	(950,560)	(656,728)
Sales and maturities of available-for-sale investments	584,186	517,707
Acquisition of SMSC, net of cash acquired	0	(731,746)
Other business acquisitions, net of cash acquired	(11,187)	(20,556)
Investments in other assets	(7,462)	(4,018)
Proceeds from sale of assets	16,200	306
Capital expenditures	(79,536)	(36,076)
Net cash used in investing activities	(448,359)	(931,111)
Cash flows from financing activities:
Repayments of revolving loan under previous credit facility	(650,000)	(130,000)
Repayments of revolving loan under new credit facility	(153,500)	0
Proceeds from borrowings on revolving loan under previous credit facility	30,000	740,000
Proceeds from borrowings on revolving loan under new credit facility	453,500	0
Proceeds from issuance of long-term borrowings	350,000	0
Deferred financing costs	(7,515)	0
Payment of cash dividends	(210,322)	(204,592)
Proceeds from sale of common stock	24,752	22,619
Contingent consideration payment	(14,700)	0
Capital lease payments	(313)	0
Excess tax benefit from share-based compensation	0	154
Net cash (used in) provided by financing activities	(178,098)	428,181
Effect of foreign exchange rate changes on cash and cash equivalents	0	986
Net decrease in cash and cash equivalents	(153,234)	(170,462)
Cash and cash equivalents at beginning of period	528,334	635,755
Cash and cash equivalents at end of period	$ 375,100	$ 465,293