Debt - Capacity on Credit Facility (Details) - Secured Debt - Credit Facility
Oct. 15, 2014
USD ($)
Dec. 31, 2015
USD ($)
Nov. 13, 2015
USD ($)
Dec. 31, 2014
USD ($)
Line of Credit Facility [Line Items]        
Maximum alternative leverage ratio 5.0      
Maximum leverage ratio 4.50      
Maximum borrowing capacity $ 300,000,000   $ 400,000,000  
Secured Debt        
Line of Credit Facility [Line Items]        
Amounts outstanding   $ 41,500,000   $ 81,400,000
Available credit facility capacity   157,500,000   218,600,000
Revolving Credit Facility        
Line of Credit Facility [Line Items]        
Maximum borrowing capacity $ 200,000,000 400,000,000   300,000,000
Amounts outstanding   201,000,000   0
Letter of Credit        
Line of Credit Facility [Line Items]        
Amounts outstanding   $ 0   $ 0