Employee Benefit Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			121 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2012
Defined contribution pension [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Percentage of employee's base salary allowed as employee contribution (in hundredths)	60.00%			60.00%
Percentage of company's match (in hundredths)	25.00%			25.00%
Percentage of eligible compensation matched by the company (in hundredths)	4.00%			4.00%
Percentage of company's additional discretionary match (in hundredths)	25.00%			25.00%
Amount of company contributions	1.6	2.3
Employee stock purchase plan, 2001 plan [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Percentage of fair market value of common stock for employee purchase (in hundredths)	85.00%
Number of additional shares reserved under purchase plan (in shares)	960,269	941,530	921,171
Number of shares of common stock reserved for issuance (in shares)	11,277,862			11,277,862
Shares issued under purchase plan (in shares)				4,639,761
Employee stock purchase plan, 2001 plan [Member] | Overlapping Stock Purchase Period 1 [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Overlapping period on purchase of common stock under purchase plan (in number of months)	24 months
Employee stock purchase plan, 2001 plan [Member] | Overlapping Stock Purchase Period 2 [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Overlapping period on purchase of common stock under purchase plan (in number of months)	18 months
Employee stock purchase plan, 2001 plan [Member] | Overlapping Stock Purchase Period 3 [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Overlapping period on purchase of common stock under purchase plan (in number of months)	12 months
Employee stock purchase plan, 2001 plan [Member] | Overlapping Stock Purchase Period 4 [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Overlapping period on purchase of common stock under purchase plan (in number of months)	6 months
Employee stock purchase plan, employees in non-US locations [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Percentage of fair market value of common stock for employee purchase (in hundredths)	85.00%
Number of shares of common stock reserved for issuance (in shares)	1,500,285			1,500,285
Shares issued under purchase plan (in shares)	610,507
Percentage of fair market value of common stock at the beginning or end of semi-annual purchase plan period, during fiscal 1995 (in hundredths)	100.00%
Management incentive compensation plan [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Compensation expense charged against operations	7.8	28.3	16.5
Cash bonus plan [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Compensation expense charged against operations	3.2	16.0	4.3
Maximum [Member] | Employee stock purchase plan, 2001 plan [Member]
Deferred compensation arrangement, by type of deferred compensation [Line Items]
Maximum automatic increase in number of common stock shares under purchase plan (in shares)	1,500,000
Percentage of outstanding shares of common stock used to determine automatic annual increase in common stock (in hundredths)	0.50%