Fair Value Measurements (Schedule Of Financial Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 117,255	$ 67,168
Marketable securities	96,261	161,310
Derivative financial instruments, assets	150	158
Total assets	213,666	228,636
Contingent purchase consideration	(8,213)	0	0
Contingent contractual non-compliance liability	(700)
Derivative financial instruments, liabilities	(166)	(92)
Total liabilities	(9,079)	(92)
U.S. Government And Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	31,635	95,388
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	22,469	24,110
Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	3,207	5,263
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	117,255	67,168
Derivative financial instruments, assets	0	0
Total assets	168,767	177,616
Contingent purchase consideration	0
Contingent contractual non-compliance liability	0
Derivative financial instruments, liabilities	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | U.S. Government And Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	31,635	95,388
Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Inputs, Level 1 [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Derivative financial instruments, assets	150	158
Total assets	43,438	33,538
Contingent purchase consideration	0
Contingent contractual non-compliance liability	0
Derivative financial instruments, liabilities	(166)	(92)
Total liabilities	(166)	(92)
Fair Value, Inputs, Level 2 [Member] | U.S. Government And Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	22,469	24,110
Fair Value, Inputs, Level 2 [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	3,207	5,263
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Derivative financial instruments, assets	0	0
Total assets	1,461	17,482
Contingent purchase consideration	(8,213)
Contingent contractual non-compliance liability	(700)
Derivative financial instruments, liabilities	0	0
Total liabilities	(8,913)	0
Fair Value, Inputs, Level 3 [Member] | U.S. Government And Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Inputs, Level 3 [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	19,877	15,060
Corporate Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	19,877	15,060
Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Corporate Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Auction Rate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	19,073	21,489
Auction Rate Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	17,612	4,007
Auction Rate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 1,461	$ 17,482