Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2017	Mar. 31, 2020	Mar. 31, 2019
Beginning Balance	$ 1,347,027	$ 1,308,284		$ 1,374,704	$ 1,230,327
Net income	2,241	70,128	$ 184,798	3,422	184,798
Other comprehensive income (loss)	(33,961)	1,026		(39,490)	(14,013)
Dividend reinvestment	52	54		157	161
Capital stock issued under employee benefit and stock plans	98	2,287		8,385	13,433
Purchase of capital stock	(52)	(54)		(157)	(161)
Additions to noncontrolling interest		443		1,527	443
Cash dividends	(16,582)	(16,763)		(49,725)	(49,583)
Ending Balance	1,298,823	1,365,405		1,298,823	1,365,405
Capital stock [Member]
Beginning Balance	103,618	102,700		103,026	102,058
Dividend reinvestment	2	2		6	5
Capital stock issued under employee benefit and stock plans	24	258		616	900
Purchase of capital stock	(2)	(2)		(6)	(5)
Ending Balance	103,642	102,958		103,642	102,958
Additional paid-in capital [Member]
Beginning Balance	536,522	522,413		528,827	511,909
Dividend reinvestment	50	52		151	156
Capital stock issued under employee benefit and stock plans	74	2,029		7,769	12,533
Purchase of capital stock	(50)	(52)		(151)	(156)
Ending Balance	536,596	524,442		536,596	524,442
Retained earnings [Member]
Beginning Balance	1,044,247	979,259		1,076,862	900,683
Net income	2,917	68,550		3,445	179,946
Cash dividends	(16,582)	(16,448)		(49,725)	(49,268)
Ending Balance	1,030,582	1,031,361		1,030,582	1,031,361
Accumulated other comprehensive loss [Member]
Beginning Balance	(378,219)	(334,632)		(373,543)	(320,325)
Other comprehensive income (loss)	(31,978)	992		(36,654)	(13,315)
Ending Balance	(410,197)	(333,640)		(410,197)	(333,640)
Non-controlling interest [Member]
Beginning Balance	40,859	38,544		39,532	36,002
Net income	(676)	1,578		(23)	4,852
Other comprehensive income (loss)	(1,983)	34		(2,836)	(698)
Additions to noncontrolling interest		443		1,527	443
Cash dividends	0	(315)		0	(315)
Ending Balance	$ 38,200	$ 40,284		$ 38,200	$ 40,284