CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income (loss)	$ 178,385	$ 57,526
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	98,462	76,456
Deferred income taxes	11,872	(9,425)
Share-based compensation expense related to equity incentive plans	27,656	24,593
Excess tax benefit from share-based compensation	0	(112)
Convertible debt derivatives - revaluation and amortization	(248)	589
Amortization of debt discount on convertible debentures	4,396	4,017
Amortization of debt issuance costs	872	109
Losses on equity method investments	361	153
Gain on sale of assets	0	(16)
Impairment of intangible assets	350	0
Unrealized impairment loss on available-for-sale investments	0	334
Special income, net	(237)	0
Changes In Operating Assets And Liabilities
Increase in accounts receivable	(693)	(116)
(Increase) decrease in inventories	(32,103)	22,334
Increase in deferred income on shipments to distributors	12,097	3,037
Decrease in accounts payable and accrued liabilities	(2,006)	(27,670)
Change in other assets and liabilities	20,191	40,462
Net cash provided by operating activities	319,355	192,271
Cash flows from investing activities:
Purchases of available-for-sale investments	(710,197)	(443,106)
Sales and maturities of available-for-sale investments	370,806	350,593
Acquisition of SMSC, net of cash acquired	0	(731,746)
Other business acquisitions, net of cash acquired	(2,174)	(20,556)
Investments in other assets	(2,951)	(2,204)
Proceeds from sale of assets	16,200	66
Capital expenditures	(55,206)	(26,212)
Net cash used in investing activities	(383,522)	(873,165)
Cash flows from financing activities:
Repayments of revolving loan under previous credit facility	(650,000)	(80,000)
Repayments of revolving loan under new credit facility	(70,000)	0
Proceeds from borrowings on revolving loan under previous credit facility	30,000	680,000
Proceeds from borrowings on revolving loan under new credit facility	360,000	0
Proceeds from issuance of long-term borrowings	350,000	0
Deferred financing costs	(7,515)	0
Payment of cash dividend	(139,768)	(135,895)
Proceeds from sale of common stock	22,196	16,318
Contingent consideration payment	(14,700)	0
Capital lease payments	(178)	0
Excess tax benefit from share-based compensation	0	112
Net cash (used in) provided by financing activities	(119,965)	480,535
Effect of foreign exchange rate changes on cash and cash equivalents	0	1,339
Net decrease in cash and cash equivalents	(184,132)	(199,020)
Cash and cash equivalents at beginning of period	528,334	635,755
Cash and cash equivalents at end of period	$ 344,202	$ 436,735