Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended	9 Months Ended
		Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Loss [Abstract]
Unrealized gain on available-for-sale securities, net of tax		$ 21		$ 21	$ 612
Net losses and past service liability for defined benefit plan, net of tax		(1,920)		(1,920)	(1,604)
Accumulated other comprehensive loss		$ (1,899)		(1,899)	$ (992)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Federal corporate tax rate		21.00%	34.00%
Reclassification adjustment	[1]			0
Maximum [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Federal corporate tax rate			35.00%
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment	[1]			(259)
Retained Earnings [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment	[1]			$ 259

[1] Adoption of Accounting Standard Update 2018-02, reclassification from accumulated other comprehensive loss to retained earnings for stranded tax effects resulting from the newly enacted Federal corporate income tax rate from 34% to 21%.