Long-term Debt (Details Textual) (USD $)	3 Months Ended		6 Months Ended							0 Months Ended			0 Months Ended	6 Months Ended		0 Months Ended	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	6 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Refinanced Term Loan [Member]	Dec. 31, 2013 Original Term Loan [Member]	Dec. 31, 2013 Original Term Loan [Member]	Jun. 30, 2014 Refinanced Term Loan [Member]	Mar. 01, 2013 Senior Unsecured Notes [Member]	Sep. 04, 2012 Senior Unsecured Notes [Member]	Feb. 28, 2007 Senior Unsecured Notes [Member]	Jan. 15, 2014 Refinanced Term Loan [Member] Secured Debt [Member]	Jun. 30, 2014 Refinanced Term Loan [Member] Secured Debt [Member]	Jun. 30, 2014 Refinanced Term Loan [Member] Maximum [Member] Secured Debt [Member]	Jan. 15, 2014 Original Term Loan [Member] Secured Debt [Member]	Dec. 31, 2012 Original Term Loan [Member] Secured Debt [Member]	Jun. 30, 2014 Original Term Loan [Member] Secured Debt [Member]	Jun. 30, 2013 Original Term Loan [Member] Secured Debt [Member]	Jun. 30, 2013 Original Term Loan [Member] Secured Debt [Member]	Dec. 31, 2013 Original Term Loan [Member] Secured Debt [Member]	Dec. 31, 2013 Original Term Loan [Member] one-month LIBOR [Member] Secured Debt [Member]	Jun. 30, 2014 Secured Debt [Member] Refinanced Term Loan [Member]	Jun. 30, 2014 Secured Debt [Member]	Jun. 30, 2014 Secured Debt [Member] one-month LIBOR [Member] Refinanced Term Loan [Member]
Debt Instrument [Line Items]
Term Loan Cure Period Maximum														135 days
Term Loan Cure Period Minimum														75 days
Long-term Debt (Textual) [Abstract]
Initial value of debt												$ 275,000,000	$ 316,200,000
Proceeds from Issuance of Long-term Debt			318,682,000	99,841,000									122,000,000
Notes redeemed										175,000,000	100,000,000					194,200,000
Extinguishment of Debt as percentage of principal amount											101.875%
Fixed interest rate of the notes												7.50%
Loss on debt extinguishment	0	0	(1,896,000)	(392,000)						(400,000)								(1,900,000)
Long-term Debt	314,260,000		314,260,000											314,300,000							194,800,000
Debt Instrument, Maximum Additional Borrowing Capacity														100,000,000
Number of additional draws on term loan (in loans)																	2
Proceeds from secured debt, net of fees and expenses																	98,400,000		99,400,000
Additional draw under term loan																				99,800,000
Fair value of term loan														314,300,000							194,800,000
Base interest rate on credit facility																						2.50%			2.00%
Interest Rate at balance sheet date																					2.70%			2.20%
Debt Instrument Interest Rate Increase Percentage																							2.00%
Interest reserve amount for term loan								3,900,000	4,000,000
Minimum Loan to Value Percentage of Net Aggregate Equipment Value														80.00%
Property Subject to or Available for Operating Lease, Net	$ 452,030,000		$ 452,030,000		$ 372,551,000	$ 309,300,000	$ 216,700,000
Debt Service Coverage Ratio															1.05