Transition report pursuant to Rule 13a-10 or 15d-10

Debt Instruments (Details)

v2.4.0.8
Debt Instruments (Details) (USD $)
In Millions, unless otherwise specified
 1 Months Ended 11 Months Ended 12 Months Ended
Sep. 30, 2013
Jul. 31, 2013
May 31, 2011
Dec. 31, 2013
Jan. 31, 2013
Jan. 31, 2012
Credit facility
            
Debt Instruments            
Maximum borrowings available $ 60.0   $ 30.0      
Decrease in the interest rate on borrowings (as a percent) 0.75%          
Non-usage charge (as a percent)       0.375%    
Minimum liquidity requirement       5.0    
Amount borrowed   10.0        
Outstanding balance of borrowings       0 0  
Available borrowing capacity       58.9 29.2  
Total debt issuance costs 0.5   1.0      
Term of credit facility agreement       4 years    
Amount of debt issuance costs that were amortized and included in interest expense       0.2 0.3 0.2
Credit facility | Minimum
            
Debt Instruments            
Non-usage charge (as a percent)     0.50%      
Credit facility | Maximum
            
Debt Instruments            
Non-usage charge (as a percent)     0.625%      
Credit facility | LIBOR
            
Debt Instruments            
Variable interest rate base     LIBOR LIBOR    
Credit facility | LIBOR | Minimum
            
Debt Instruments            
Margin (as a percent)     2.75% 2.00%    
Credit facility | LIBOR | Maximum
            
Debt Instruments            
Margin (as a percent)     3.00% 2.25%    
Credit facility | Alternate base rate
            
Debt Instruments            
Variable interest rate base     alternate base rate alternate base rate    
Credit facility | Alternate base rate | Minimum
            
Debt Instruments            
Margin (as a percent)     1.75% 1.00%    
Credit facility | Alternate base rate | Maximum
            
Debt Instruments            
Margin (as a percent)     2.00% 1.25%    
Credit facility | Federal funds effective rate
            
Debt Instruments            
Variable interest rate base     federal funds effective rate      
Margin (as a percent)     0.50%      
Credit facility | Adjusted LIBOR rate
            
Debt Instruments            
Variable interest rate base     adjusted LIBOR rate      
Margin (as a percent)     1.00%      
Letters of credit
            
Debt Instruments            
Maximum borrowings available 15.0   5.0      
Reduction in annual charge on outstanding amount (as a percent) 0.75%          
Outstanding amount       1.1 0.8  
Cash collateral considered to be restricted cash         $ 0.8  
Letters of credit | Minimum
            
Debt Instruments            
Annual charge on outstanding amount (as a percent)     2.75% 2.00%    
Letters of credit | Maximum
            
Debt Instruments            
Annual charge on outstanding amount (as a percent)     3.00% 2.25%