Fair Value Measurements - Financial Assets and Liabilities at Fair Value on Recurring Basis (Details) (Fair Value, Measurements, Recurring, USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Level 1
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Interest rate swaps financial liabilities $ 0 $ 0
Level 2
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Interest rate swaps financial liabilities (1,630) (1,122)
Level 3
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Interest rate swaps financial liabilities 0 0
Fair Value
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Interest rate swaps financial liabilities $ (1,630) $ (1,122)