Consolidated Statements of Comprehensive Earnings (unaudited) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Earnings	$ 54,882	$ 45,344
Change in Funded Status of Defined Benefit Plans:
Amortization of Net Actuarial Loss	314	500
Tax Expense	(117)	(188)
Comprehensive Earnings	$ 55,079	$ 45,656

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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