Financial Instruments (Details) (USD $)	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Condition on amount invested in any single issuer or fund	The amount invested in any single issuer or fund may not exceed 20% of the issuer's or the fund's total assets measured at the time of purchase or $10 million, whichever is greater.
Maximum percentage of amount invested in any single issuer or fund	20.00%
Maximum amount invested in any single issuer or fund	$ 10,000,000
Outstanding foreign currency forward and swap contracts	2,400,000,000
Foreign currency contracts, assets	24,071,000	15,671,000
Foreign currency contracts, liabilities	(6,900,000)	(9,535,000)
Total notional value in USD	17,171,000	6,136,000
Other current assets	1,125,809,000	747,676,000
Other current liabilities	(1,344,666,000)	(1,285,368,000)
Derivative Financial Instruments, Assets [Member] | Derivative Designated as Hedging Instruments [Member]
Other current assets	19,579,000	8,559,000
Derivative Financial Instruments, Assets [Member] | Derivative Not Designated As Hedging Instruments [Member]
Other current assets	4,492,000	7,112,000
Derivative Financial Instruments, Liabilities [Member] | Derivative Designated as Hedging Instruments [Member]
Other current liabilities	(778,000)	(2,425,000)
Derivative Financial Instruments, Liabilities [Member] | Derivative Not Designated As Hedging Instruments [Member]
Other current liabilities	(6,122,000)	(7,110,000)
Fair Value, Inputs, Level 1 [Member]
Foreign currency contracts, assets
Foreign currency contracts, liabilities
Total notional value in USD
Fair Value, Inputs, Level 2 [Member]
Foreign currency contracts, assets	24,071,000	15,671,000
Foreign currency contracts, liabilities	(6,900,000)	(9,535,000)
Total notional value in USD	17,171,000	6,136,000
Fair Value, Inputs, Level 3 [Member]
Foreign currency contracts, assets
Foreign currency contracts, liabilities
Total notional value in USD