Earnings per Share (Details) - USD ($)		3 Months Ended								12 Months Ended
		Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights										28,000	65,000	74,000
Numerator - Basic and Diluted [Abstract]
Net income		$ 267,043	$ 3,983,441	$ 1,803,351	$ (524,457)	$ (4,464)	$ 4,155,136	$ 2,656,534	$ (311,125)	$ 5,529,378	$ 6,496,081	$ 8,275,128
Less: dividends paid										5,822,259	5,639,791	5,289,911
Payments of Ordinary Dividends, Common Stock										(5,822,259)	(5,639,791)	(5,289,911)
Undistributed earnings	[1]									$ (293,000)	$ 856,000	$ 2,985,000
Percentage allocated to common shares (in hundredths)										100.00%	99.40%	99.40%
Undistributed earnings allocated to common shares	[1]									$ (293,000)	$ 851,000	$ 2,966,000
Add: dividends declared allocated to common shares	[2]									5,798,000	5,609,000	5,263,000
Net income available to common shares										$ 5,505,000	$ 6,460,000	$ 8,229,000
Denominator - Basic [Abstract]
Weighted average Common shares (in shares)	[3]									7,066,925	7,002,694	6,918,725
Per common share net income [Abstract]
Basic (in dollars per share)		$ 0.05	$ 0.56	$ 0.25	$ (0.08)	$ 0.00	$ 0.59	$ 0.38	$ (0.05)	$ 0.78	$ 0.92	$ 1.19
Diluted (in dollars per share)										$ 0.78	$ 0.92	$ 1.19
Percentage allocated to common shares - weighted average [Abstract]
Weighted average Common shares (in shares)	[3]									7,066,925	7,002,694	6,918,725
Unvested participating shares (in shares)	[4]									0	45,500	44,750
Total (in shares)										7,066,925	7,048,194	6,963,475

[1] Percentage allocated to common shares: Weighted average: Common shares outstanding 7,066,925 7,002,694 6,918,725Unvested participating shares outstanding (d)— 45,500 44,750Total7,066,925 7,048,194 6,963,475 Percentage allocated to common shares100.0% 99.4% 99.4% Undistributed earnings (loss) ($000)(293) 856 2,985Allocated to common shares(293) 851 2,966

[2] Represents dividends paid on common shares, exclusive of unvested participating shares.

[3] Under our Incentive Compensation Plan, recipients of performance share awards receive unvested non-participating shares, as further discussed in Note 16 of the Notes to Consolidated Financial Statements. Unvested non-participating shares become dilutive in the interim quarter-end in which the performance objective is met. If the performance objective continues to be met through the end of the performance period, these shares become unvested participating shares as of the fiscal year-end, as further discussed below in Note (c). The weighted average number of unvested non-participating shares outstanding during a period is included in the diluted earnings per common share calculation using the treasury stock method, unless the effect of including such shares would be antidilutive. There were no unvested non-participating shares outstanding as of June 30, 2016, 2015 and 2014.

[4] Certain awards under our shareholder approved incentive compensation plan, as further discussed in Note 16 of the Notes to Consolidated Financial Statements, provide the recipients of the awards all the rights of a shareholder of Delta including the right to dividends declared on common shares. Any unvested shares which are participating in dividends are considered participating securities and are included in our computation of basic and diluted earnings per share using the two-class method unless the effect of including such shares would be antidilutive. As of June 30, 2016, there were 28,000 participating shares outstanding which were excluded from the computation of earnings allocated to common shares for 2016, as the holders of the unvested participating shares do not have a contractual obligation to share in losses. There were no antidilutive shares in 2015 and 2014. There were 28,000, 65,000 and 74,000 unvested participating shares outstanding as of June 30, 2016, 2015 and 2014, respectively.