Financial Instruments - Additional Information (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Fair Value, Measurements, Recurring [Member]      
Derivative [Line Items]      
Fair value of interest rate swap $ 821,000   $ 1,096,000
Interest Rate Swap [Member]      
Derivative [Line Items]      
Length of interest rate swap 3 years    
Notional amount of interest rate cash flow hedge derivatives 500,000,000    
Libor rate 0.52%    
Effective interest rate 2.14%    
Basis spread on variable rate 1.63%    
Deferred expenses related to derivative instruments 800,000    
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]      
Derivative [Line Items]      
Cash flow hedge loss reclassified to interest expense 400,000 400,000  
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]      
Derivative [Line Items]      
Fair value of interest rate swap $ 821,000   $ 1,096,000