Consolidated Statements of Comprehensive Earnings (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net Earnings	$ 50,319	$ 39,903	$ 88,029	$ 70,004
Change in Funded Status of Defined Benefit Plans:
Amortization of Net Actuarial Loss	163	238	326	476
Tax Expense	(57)	(83)	(114)	(166)
Comprehensive Earnings	$ 50,425	$ 40,058	$ 88,241	$ 70,314