CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 256,069	$ 293,422
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	75,170	80,153
Deferred income taxes	7,185	17,380
Share-based compensation expense related to equity incentive plans	28,470	27,785
Excess tax benefit from share-based compensation	(441)	(1,240)
Convertible debt derivatives - revaluation and amortization	427	(192)
Amortization of convertible debenture issuance costs	165	165
Amortization of debt discount on convertible debentures	5,580	5,101
Losses (gains) on equity method investments	60	(185)
Gain on sale of assets	(212)	(89)
Unrealized impairment loss on available-for-sale investments	3,213	1,263
Special income	(1,000)	0
Changes in operating assets and liabilities:
Decrease (increase) in accounts receivable	31,925	(3,016)
Increase in inventories	(36,297)	(20,779)
(Decrease) increase in deferred income on shipments to distributors	(24,258)	41,422
Decrease in accounts payable and accrued liabilities	(67,198)	(19,279)
Change in other assets and liabilities	15,140	8,213
Net cash provided by operating activities	293,998	430,124
Cash flows from investing activities:
Purchases of available-for-sale investments	(962,119)	(859,307)
Sales and maturities of available-for-sale investments	793,238	838,995
Purchase of Silicon Storage Technology, Inc, net of cash received	0	(112,707)
Investment in other assets	(6,878)	(14,843)
Proceeds from sale of assets	212	30,559
Capital expenditures	(58,582)	(100,114)
Net cash used in investing activities	(234,129)	(217,417)
Cash flows from financing activities:
Payment of cash dividend	(198,919)	(256,808)
Proceeds from sale of common stock	40,410	51,347
Excess tax benefit from share-based compensation	441	1,240
Net cash used in financing activities	(158,068)	(204,221)
Net (decrease) increase in cash and cash equivalents	(98,199)	8,486
Cash and cash equivalents at beginning of period	703,924	492,130
Cash and cash equivalents at end of period	$ 605,725	$ 500,616