Stock-Based Compensation Stock-Based Compensation (Details 6) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Common Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Deferred Compensation Arrangement with Individual Discount on Contribution, Maximum Percent	10.00%
Additional shares reserved for future issuance	5,792,000
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 191	$ 263	$ 176
Common Stock, Shares, Issued	68,000	77,000	128,000
Grants (in dollars per share)	$ 27.05	$ 28.38	$ 22.53
Rabbi trust
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Common Stock, Shares Held in Employee Trust, Shares	690,000	706,000	653,000