Basis of Presentation (Cash Cash Equivalents and Short-term Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014
Amortized Cost Basis	$ 151,858	$ 151,854
Available-for-sale Securities, Gross Unrealized Gain	116	55
Gross Unrealized Losses	(17)	(96)
Total available-for-sale investments, estimated fair value	151,957	151,813
Reported as:
Cash equivalents	25,020	32,611
Short-term investments	126,937	47,181
Long-term investments	0	72,021
Contractual maturities of investments:
Investments due within one year	75,972	79,792
Investments due after one year	75,985	72,021
Money Market Funds
Amortized Cost Basis	25,020	32,611
Available-for-sale Securities, Gross Unrealized Gain	0	0
Gross Unrealized Losses	0	0
Total available-for-sale investments, estimated fair value	25,020	32,611
Mutual Funds
Amortized Cost Basis	1,909	1,964
Available-for-sale Securities, Gross Unrealized Gain	21	0
Gross Unrealized Losses	0	(55)
Total available-for-sale investments, estimated fair value	1,930	1,909
Commercial Paper
Amortized Cost Basis	24,583	30,374
Available-for-sale Securities, Gross Unrealized Gain	6	5
Gross Unrealized Losses	0	0
Total available-for-sale investments, estimated fair value	24,589	30,379
Corporate Debt
Amortized Cost Basis	69,163	63,621
Available-for-sale Securities, Gross Unrealized Gain	69	35
Gross Unrealized Losses	(8)	(39)
Total available-for-sale investments, estimated fair value	69,224	63,617
Municipal Securities
Amortized Cost Basis	5,434	5,435
Available-for-sale Securities, Gross Unrealized Gain	4	5
Gross Unrealized Losses	(3)	(1)
Total available-for-sale investments, estimated fair value	5,435	5,439
Asset Backed Securities
Amortized Cost Basis	20,067	17,049
Available-for-sale Securities, Gross Unrealized Gain	11	6
Gross Unrealized Losses	(3)	(1)
Total available-for-sale investments, estimated fair value	20,075	17,054
Mortgage Backed Securities
Amortized Cost Basis	4,882
Available-for-sale Securities, Gross Unrealized Gain	0
Gross Unrealized Losses	(3)
Total available-for-sale investments, estimated fair value	4,879
Internatinal Government Securities
Amortized Cost Basis	800	800
Available-for-sale Securities, Gross Unrealized Gain	5	4
Gross Unrealized Losses	0	0
Total available-for-sale investments, estimated fair value	$ 805	$ 804