Condensed Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Condensed Consolidated Statements of Comprehensive Earnings
Net earnings	$ 91,318	$ 77,579	$ 144,691	$ 126,699
Other comprehensive earnings:
Foreign currency translation adjustments	(13,355)	323	(2,202)	(1,411)
Net gain (loss) on foreign currency transactions designated as hedges of net investments in foreign subsidiaries (Note 8)	650	925	(395)	1,574
Taxes on changes in foreign currency translation adjustments	130	(280)	(210)	103
Foreign currency translation and transactions adjustments, net of tax	(12,575)	968	(2,807)	266
Unrealized gain on fair value adjustment of derivative instruments (Note 8)	45,298	9,609	34,004	28,172
Reclassification of net realized (gain) loss on derivatives to earnings (Note 8)	(7,262)	(10,895)	4,394	(18,721)
Taxes on changes on derivative transactions	(790)	32	(772)	(176)
Derivative adjustments, net of tax	37,246	(1,254)	37,626	9,275
Amortization of pension and other postretirement plan:
Net prior service cost	240	176	481	352
Net loss	628	242	1,259	481
Foreign currency exchange rate changes on pension and other postretirement benefit plan liabilities	1,225	(301)	(277)	2
Taxes on changes in pension and other postretirement benefit plan liability adjustments, net of foreign currency exchange rate changes	(592)	6	(352)	(203)
Pension and other postretirement benefit plan adjustments, net of tax	1,501	123	1,111	632
Total comprehensive earnings	$ 117,490	$ 77,416	$ 180,621	$ 136,872