Quarterly report pursuant to Section 13 or 15(d)

Borrowings (Credit Facility) (Narrative) (Details)

v3.5.0.2
Borrowings (Credit Facility) (Narrative) (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Jul. 13, 2016
Sep. 30, 2016
Sep. 30, 2016
Dec. 31, 2015
Line of Credit Facility [Line Items]        
Debt instrument outstanding   $ 300,000 $ 300,000 $ 340,000
Senior Secured Revolving Credit Facility [Member]        
Line of Credit Facility [Line Items]        
Maximum borrowing capacity   500,000 500,000  
Current borrowing capacity $ 385,000 $ 385,000 $ 385,000  
Increase in interest rate on credit facility 0.25%      
Interest rate at period end (as a percent)   2.92% 2.92%  
Debt instrument outstanding   $ 0 $ 0 $ 40,000
Unused capacity, commitment fee (as a percent)   0.50%    
Debt instrument maturity date     Mar. 11, 2019  
Senior Secured Revolving Credit Facility [Member] | Minimum [Member]        
Line of Credit Facility [Line Items]        
Debt instrument interest rate   2.00%    
Senior Secured Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member]        
Line of Credit Facility [Line Items]        
Debt instrument interest rate 2.00%      
Senior Secured Revolving Credit Facility [Member] | Maximum [Member]        
Line of Credit Facility [Line Items]        
Debt instrument interest rate   3.00%    
Senior Secured Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member]        
Line of Credit Facility [Line Items]        
Debt instrument interest rate 3.00%