Derivative Financial Instruments - Income Statement Effect (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	$ 5,625	$ (5,873,958)	$ (1,009,075)	$ (7,590,975)
Eurodollar Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	6,000	(4,745,000)	(1,009,000)	(6,306,000)
InterestRateSwaptionMember
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	0	(1,129,000)	0	(1,285,000)
Parent Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	6,000	(146,000)	(1,009,000)	(170,000)
Parent Co [Member] | Eurodollar Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	6,000	(146,000)	(1,009,000)	(170,000)
Parent Co [Member] | InterestRateSwaptionMember
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains on derivative instruments	$ 0	$ 0	$ 0	$ 0