Capital Stock Other Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
	Dec. 22, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2015
Capital Stock [Abstract]
Shares Paid for Tax Withholding for Share Based Compensation		395	348	370
Adjustments Related to Tax Withholding for Share-based Compensation		$ 15,575	$ 13,233	$ 12,139
Stock Repurchased and Retired During Period, Shares	5,568	6,636		11,697
Stock Repurchased and Retired During Period, Value	$ 225,490		$ 253,649	$ 381,672
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	169,019
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	56,471				1,000,000
Common Stock, Dividends, Per Share, Declared		$ 1.36	$ 1.12	$ 0.88
Dividends Payable		$ 29,058	$ 23,623	$ 21,153