Derivative Financial Instruments - Summary of Eurodollar Futures Positions (Details) (Eurodollar Future [Member], USD $)	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate	1.71%	2.02%
Notional Amount	$ 480,000,000	$ 257,353,000
Open Equity	(880,000)	4,898,000
Year 2014 Expiration [Member]
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate		0.40%
Notional Amount		262,500,000
Open Equity		(189,000)
Year 2015 Expiration [Member]
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate	0.65%	0.80%
Notional Amount	550,000,000	275,000,000
Open Equity	(789,000)	(146,000)
Year 2016 Expiration [Member]
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate	1.54%	1.90%
Notional Amount	550,000,000	250,000,000
Open Equity	159,000	1,367,000
Year 2017 Expiration [Member]
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate	2.46%	3.03%
Notional Amount	400,000,000	250,000,000
Open Equity	202,000	2,291,000
Year 2018 Expiration [Member]
Derivatives, Fair Value [Line Items]
Locked-In LIBOR Rate	2.98%	3.77%
Notional Amount	400,000,000	250,000,000
Open Equity	$ (452,000)	$ 1,575,000