Selected Quarterly Financial Information (unaudited) (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2014	Mar. 31, 2015
Selected Quarterly Financial Information (unaudited)
Revenues	$ 35,333,108us-gaap_Revenues	$ 32,583,990us-gaap_Revenues	$ 20,358,211us-gaap_Revenues	$ 15,853,840us-gaap_Revenues	$ 9,870,427us-gaap_Revenues	$ 13,707,591us-gaap_Revenues	$ 6,055,682us-gaap_Revenues	$ 29,633,700us-gaap_Revenues	$ 104,129,149us-gaap_Revenues
Operating income/(loss)	10,493,169us-gaap_OperatingIncomeLoss	10,825,590us-gaap_OperatingIncomeLoss	3,476,450us-gaap_OperatingIncomeLoss	5,200,271us-gaap_OperatingIncomeLoss	992,366us-gaap_OperatingIncomeLoss	3,908,734us-gaap_OperatingIncomeLoss	(509,733)us-gaap_OperatingIncomeLoss	4,391,368us-gaap_OperatingIncomeLoss	29,995,480us-gaap_OperatingIncomeLoss
Net (loss)/income	$ 8,828,251	$ 8,996,605	$ 3,768,677	$ 3,667,249	$ (1,310,643)	$ 5,570,247	$ (1,425,761)	$ 2,833,843	$ 25,260,782
Earnings per common share, basic and diluted (in dollars per share)	$ 0.15us-gaap_EarningsPerShareBasicAndDiluted	$ 0.16us-gaap_EarningsPerShareBasicAndDiluted	$ 0.07us-gaap_EarningsPerShareBasicAndDiluted	$ 0.07us-gaap_EarningsPerShareBasicAndDiluted	$ (0.03)us-gaap_EarningsPerShareBasicAndDiluted	$ 0.20us-gaap_EarningsPerShareBasicAndDiluted	$ (0.08)us-gaap_EarningsPerShareBasicAndDiluted	$ 0.09us-gaap_EarningsPerShareBasicAndDiluted	$ 0.45us-gaap_EarningsPerShareBasicAndDiluted

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

No definition available.

+ Details

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- Definition

Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1377-109256

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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