CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 78,579	$ 78,710
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	50,410	25,245
Deferred income taxes	5,298	2,927
Share-based compensation expense related to equity incentive plans	12,656	9,986
Excess tax benefit from share-based compensation	0	(20)
Convertible debt derivatives - revaluation and amortization	16	330
Amortization of debt discount on convertible debentures	2,161	1,975
Amortization of debt issuance costs	327	54
Losses on equity method investments	260	121
Special charge	1,392	0
Changes In Operating Assets And Liabilities
Increase in accounts receivable	(2,462)	(2,814)
(Increase) decrease in inventories	(13,957)	316
Increase in deferred income on shipments to distributors	10,865	2,084
Increase in accounts payable and accrued liabilities	3,909	4,766
Change in other assets and liabilities	14,977	5,291
Net cash provided by operating activities	164,431	128,971
Cash flows from investing activities:
Purchases of available-for-sale investments	(376,460)	(29,130)
Sales and maturities of available-for-sale investments	182,614	139,439
Business acquisitions, net of cash acquired	(2,174)	(20,556)
Investments in other assets	(1,616)	(1,609)
Proceeds from sale of assets	16,200	50
Capital expenditures	(27,757)	(10,304)
Net cash (used in) provided by investing activities	(209,193)	77,890
Cash flows from financing activities:
Repayments of revolving loan under previous credit facility	(650,000)	0
Proceeds from borrowings on revolving loan under previous credit facility	30,000	0
Proceeds from borrowings on revolving loan under new credit facility	260,000	0
Proceeds from issuance of long-term borrowings	350,000	0
Deferred financing costs	(7,515)	0
Payment of cash dividend	(69,682)	(67,749)
Proceeds from sale of common stock	6,900	4,961
Capital lease payments	(44)	0
Excess tax benefit from share-based compensation	0	20
Net cash used in financing activities	(80,341)	(62,768)
Net (decrease) increase in cash and cash equivalents	(125,103)	144,093
Cash and cash equivalents at beginning of period	528,334	635,755
Cash and cash equivalents at end of period	$ 403,231	$ 779,848