Goodwill & Intangible Assets (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended
	Sep. 30, 2011 years	Mar. 31, 2011	Sep. 30, 2011 Acquired Software And Core Technology [Member]	Sep. 30, 2011 Acquired Software And Core Technology [Member]	Sep. 30, 2011 Other Acquired Intangible Assets [Member]	Sep. 30, 2010 Other Acquired Intangible Assets [Member]	Sep. 30, 2011 Other Acquired Intangible Assets [Member]	Sep. 30, 2010 Other Acquired Intangible Assets [Member]	Sep. 30, 2010 Acquired Software [Member]	Sep. 30, 2011 Acquired Software [Member] years	Sep. 30, 2010 Acquired Software [Member]	Sep. 30, 2011 Customer Relationships [Member] years
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 141,356	$ 128,177
Intangible Assets, Net (Excluding Goodwill)	48,939	47,686
Amortization expenses included in cost of product			$ 1,100	$ 2,200	$ 521	$ 477	$ 976,000	$ 954	$ 995		$ 2,000
Weighted average useful life of acquired intangible assets	11.0									5.5		15.4