Stock-Based Compensation Non-employee Directors Equity Plan (Details 11) - $ / shares	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 41.26	$ 40.87
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	882,000	1,570,000
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date	625,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Stock Issued During Period, Shares, Employee Stock Ownership Plan	141,000	128,000	164,000
Restricted Stock Units (RSUs) [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date	15,000	12,000	11,000
Common Stock [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date	15,000	19,000	30,000