Subsequent Event (Narrative) (Details)		12 Months Ended
	Jul. 10, 2019 USD ($)	Jun. 30, 2019
3.24% Senior Notes Due July 10, 2026 [Member] | Note Purchase Agreement [Member]
Subsequent Event [Line Items]
Interest rate		3.24%
Maturity date		Jul. 10, 2026
3.45% Senior Notes Due July 10, 2029 [Member] | Note Purchase Agreement [Member]
Subsequent Event [Line Items]
Interest rate		3.45%
Maturity date		Jul. 10, 2029
Subsequent Event [Member]
Subsequent Event [Line Items]
Debt to consolidated EBITDA ratio	3.50
Maximum percentage of secured and unsecured debt allowed	10.00%
Subsequent Event [Member] | 3.24% Senior Notes Due July 10, 2026 [Member] | Note Purchase Agreement [Member]
Subsequent Event [Line Items]
Principal amount	$ 250,000,000
Subsequent Event [Member] | 3.45% Senior Notes Due July 10, 2029 [Member] | Note Purchase Agreement [Member]
Subsequent Event [Line Items]
Principal amount	$ 250,000,000