Repurchases of Common Shares Level 4 (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Stock Repurchased During Period, Shares	46,949,000
Payments for Repurchase of Common Stock	$ 2,688	$ 43,679
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	46,076,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 116,888
treasury stock 2008 board authorization	11,616,847