CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Cash flows from operating activities:
Net income	$ 418,950	$ 217,005	$ 245,587
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	106,612	90,057	96,046
Deferred income taxes	24,003	22,330	28,111
Share-based compensation expense related to equity incentive plans	36,812	36,778	32,481
Excess tax benefit from share-based compensation	(1,854)	(2,094)	(6,798)
Convertible debt derivatives - revaluation and amortization	(185)	230	(944)
Amortization of junior convertible debenture issuance costs	219	215	215
Amortization of debt discount on convertible debentures	6,847	6,258	5,171
Gains on equity method investments	(157)	0	0
Gain on sale of assets	(89)	(100)	(100)
Unrealized impairment loss on available-for-sale investments	4,659	4,750	3,560
Special charges	0	1,238	860
Sales (purchases) of trading securities, net	0	86,970	(73,510)
(Gain) loss on trading securities	0	(7,425)	6,332
Changes in operating assets and liabilities:
Decrease (increase) in accounts receivable	6,341	(49,078)	50,832
(Increase) decrease in inventories	(22,068)	15,239	(4,110)
Increase (decrease) in deferred income on shipments to distributors	38,781	15,010	(11,510)
(Decrease) increase in accounts payable and accrued liabilities	(638)	29,583	(25,097)
Change in other assets and liabilities	(35,572)	(14,919)	(38,473)
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,008,056)	(1,576,044)	(2,479,175)
Sales and maturities of available-for-sale investments	1,055,286	1,502,127	2,583,152
Purchase of Silicon Storage Technology, Inc, net of cash received	(112,707)	0	0
Investment in Silicon Storage Technology, Inc.	0	(58,402)	0
Investment in other assets	(29,587)	(15,439)	(21,600)
Proceeds from sale of assets	31,668	100	166
Capital expenditures	(124,454)	(47,604)	(102,370)
Net cash (used in) provided by investing activities	(187,850)	(195,262)	(19,827)
Cash flows from financing activities:
Payment of cash dividend	(256,811)	(249,556)	(246,657)
Repurchase of common stock	0	0	(123,929)
Proceeds from sale of common stock	71,940	36,478	33,555
Excess tax benefit from share-based compensation	1,854	2,094	6,798
Net cash used in financing activities	(183,017)	(210,984)	(330,233)
Net increase (decrease) in cash and cash equivalents	211,794	45,801	(41,407)
Cash and cash equivalents at beginning of year	492,130	446,329	487,736
Cash and cash equivalents at end of year	$ 703,924	$ 492,130	$ 446,329