Stock-Based Employee Compensation Stock-Based Employee Compensation (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Employee Stock Purchase Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Employee Stock Purchase Plans	413,946	947,187
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	7.9	7.9
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	88,406	730,214
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1.8
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	6.7	6.7
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	214,965	282,626
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1.4