Income Taxes (Reconciliation of U.S.Federal Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Income Tax Contingency [Line Items]
U.S. statutory rate	21.00%	28.00%	35.00%
U.S. Federal income tax at statutory rate	$ 16,361	$ 17,094	$ 35,524
State and local income taxes, net of Federal benefit	2,727	1,883	1,729
Tax credits	(1,808)	(1,825)	(1,430)
Valuation allowance	2,142	1,530	444
Effect of foreign operations, net	2,103	(1,396)	(1,477)
Stock compensation	35	1,049	(61)
Capitalized acquisition costs	69	48	231
Nontaxable income	(828)	(9)	(4,437)
Disallowed interest	1,600	1,888	2,011
Net favorable recovery	(2,670)	0	0
Other	1,085	(1,438)	(285)
Global intangible low taxed income (GILTI) tax	365	0	0
Provision for income taxes	20,311	27,772	32,249
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
U.S. Tax Reform transition tax	(827)	9,609	0
Impact of rate change on deferred taxes	0	(1,615)	0
Administration of the Treasury, Belgium [Member]
Income Tax Contingency [Line Items]
Impact of rate change on deferred taxes	0	1,040	0
Other Jurisdiction [Member]
Income Tax Contingency [Line Items]
Impact of rate change on deferred taxes	$ (43)	$ (86)	$ 0