Intangible Assets and Goodwill (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Goodwill, Gross Book Value
Changes in the carrying value of goodwill
Gross Book Value, at the beginning of period	$ 2,436,945	$ 2,473,552
Impact of excess tax basis amortization	(21,573)	(21,694)
Business acquisition (see Note 2)	28,983
Other, including changes in foreign exchange rates	(13,290)	(14,913)
Goodwill, Gross	2,431,065	2,436,945
Goodwill, Accumulated Impairment
Changes in the carrying value of goodwill
Accumulated Impairment, at the beginning of period	(1,161,900)	(1,161,900)
Impact of excess tax basis amortization	0	0
Business acquisition (see Note 2)	0
Other, including changes in foreign exchange rates	0	0
Goodwill, Impaired, Accumulated Impairment Loss	(1,161,900)	(1,161,900)
Goodwill, Net Book Value
Changes in the carrying value of goodwill
Net Book Value, at the beginning of period	1,275,045	1,311,652
Impact of excess tax basis amortization	(21,573)	(21,694)
Business acquisition (see Note 2)	28,983
Other, including changes in foreign exchange rates	(13,290)	(14,913)
Net Book Value, at the end of period	$ 1,269,165	$ 1,275,045