Subsequent Events - Revolving Credit Facility (Details) - USD ($)
 12 Months Ended
Feb. 12, 2016
Oct. 15, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Nov. 13, 2015
Line of Credit Facility [Line Items]            
Proceeds from long-term debt     $ 0 $ 67,845,000 $ 0  
Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Maximum borrowing capacity   $ 300,000,000       $ 400,000,000
Revolving Credit Facility | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Maximum borrowing capacity   $ 200,000,000 400,000,000 300,000,000    
Amount outstanding under the credit facility     $ 201,000,000 $ 0    
Scenario 1 | Minimum | Revolving Credit Facility | Base Rate | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Basis spread on variable rate   1.25%        
Scenario 1 | Maximum | Revolving Credit Facility | Base Rate | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Basis spread on variable rate   2.25%        
Scenario 3 | Minimum | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Basis spread on variable rate   2.25%        
Scenario 3 | Maximum | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Basis spread on variable rate   3.25%        
Subsequent Event | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Amount outstanding under the credit facility $ 206,000,000          
Subsequent Event | Revolving Credit Facility | Secured Debt | Credit Facility            
Line of Credit Facility [Line Items]            
Proceeds from long-term debt $ 5,000,000