CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net income	$ 195,359	$ 181,947
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	131,484	131,809
Deferred income taxes	(35,999)	(4,497)
Share-based compensation expense related to equity incentive plans	37,138	28,594
Excess tax benefit from share-based compensation	(407)	(982)
Amortization of debt discount on convertible debentures	23,746	4,810
Amortization of debt issuance costs	1,920	1,088
Losses on equity method investments	233	67
Gain on sale of assets	(860)	0
Impairment of intangible assets	530	556
Realized gain on available-for-sale investment	(13,959)	0
Realized gain on equity method investment	(2,225)	0
Accretion (Amortization) of Discounts and Premiums, Investments	4,732	5,066
Special charges	511	0
Changes In Operating Assets And Liabilities
Decrease (increase) in accounts receivable	5,170	(29,429)
(Increase) decrease in inventories	(4,597)	32,052
Increase in deferred income on shipments to distributors	13,492	11,787
Decrease in accounts payable and accrued liabilities	(31,443)	(15,817)
Change in other assets and liabilities	6,589	10,783
Net cash provided by operating activities	331,414	357,834
Cash flows from investing activities
Purchases of available-for-sale investments	(1,112,089)	(350,598)
Sales and maturities of available-for-sale investments	795,771	547,037
Sale of equity method investment	2,667	0
Acquisition of Micrel, net of cash acquired	(343,928)	0
Acquisition of ISSC, net of cash acquired	0	(252,469)
Purchase of additional controlling interest in ISSC	(18,051)	(1,765)
Acquisition of Supertex, net of cash acquired	0	(375,365)
Investments in other assets	(2,981)	(3,659)
Proceeds from sale of assets	14,296	0
Capital expenditures	(63,554)	(83,372)
Net cash used in investing activities	(727,869)	(520,191)
Cash flows from financing activities:
Repayments of revolving loan under credit facility	(190,000)	(308,500)
Proceeds from borrowings on revolving loan under credit facility	1,024,500	632,875
Repayments of long-term borrowings	0	(8,750)
Deferred financing costs	(406)	0
Payment of cash dividends	(145,016)	(142,644)
Repurchase of common stock	(363,829)	0
Proceeds from sale of common stock	13,520	14,035
Tax payments related to shares withheld for vested restricted stock units	(11,124)	(10,306)
Capital lease payments	(334)	(298)
Excess tax benefit from share-based compensation	407	982
Net cash provided by financing activities	327,718	177,394
Effect of foreign exchange rate changes on cash and cash equivalents	0	(201)
Net (decrease) increase in cash and cash equivalents	(68,737)	14,836
Cash and cash equivalents at beginning of period	607,815	466,603
Cash and cash equivalents at end of period	$ 539,078	$ 481,439