Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurement - Fair Value of Liabilities Measured on a Recurring Basis (Details)

v2.4.0.6
Fair Value Measurement - Fair Value of Liabilities Measured on a Recurring Basis (Details) (Fair Value, Measurements, Recurring [Member], USD $)
Mar. 31, 2013
Dec. 31, 2012
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
   
Liabilities, Fair Value Disclosure [Abstract]    
Derivative instruments $ 7,465,148 $ 8,214,582
Fair Value, Inputs, Level 3 [Member]
   
Liabilities, Fair Value Disclosure [Abstract]    
Contingent consideration 1,147,408 1,147,408
Estimate of Fair Value, Fair Value Disclosure [Member]
   
Liabilities, Fair Value Disclosure [Abstract]    
Total liabilities $ 8,612,556 $ 9,361,990