Stock-Based Compensation (ESPP - Purchase Option Activity) (Details) shares in Thousands	6 Months Ended
	Sep. 30, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Exercised	(270)
Employee Stock Purchase Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding at March 31, 2015	54
Granted	237
Exercised	(108)
Outstanding at September 30, 2015	183
Outstanding at March 31, 2015, Weighted-Average Exercise Price Per Share | $ / shares	$ 86.47
Granted, Weighted-Average Exercise Price Per Share | $ / shares	78.07
Exercised, Weighted-Average Exercise Price Per Share | $ / shares	89.33
Outstanding at September 30, 2015, Weighted-Average Exercise Price Per Share | $ / shares	$ 73.93