Intangible Assets and Goodwill (Details 3) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2013
Goodwill, Gross Book Value
Changes in the carrying value of goodwill
Gross Book Value, at the beginning of period	$ 2,431,065
Impact of excess tax basis amortization	(10,786)
Other, including changes in foreign exchange rates	(6,890)
Gross Book Value, at the end of period	2,413,389
Goodwill, Accumulated Impairment
Changes in the carrying value of goodwill
Accumulated Impairment, at the beginning of period	(1,161,900)
Impact of excess tax basis amortization	0
Other, including changes in foreign exchange rates	0
Accumulated Impairment, at the end of period	(1,161,900)
Goodwill, Net Book Value
Changes in the carrying value of goodwill
Net Book Value, at the beginning of period	1,269,165
Impact of excess tax basis amortization	(10,786)
Other, including changes in foreign exchange rates	(6,890)
Net Book Value, at the end of period	$ 1,251,489