Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements (Details)

v3.10.0.1
Fair Value Measurements (Details) - USD ($)
$ in Millions
12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Dec. 15, 2014
Jul. 09, 2010
$150 senior unsecured notes        
Liabilities:        
Long-term Debt, Gross $ 149.7 $ 149.5    
Additional disclosures        
Term of debt issued 10 years      
Stated interest rate 5.50%     5.50%
Line of Credit [Member]        
Liabilities:        
Long-term Debt, Gross $ 95.7 68.0    
$180 term loan        
Liabilities:        
Long-term Debt, Gross 0.0 148.5    
$100 Series A Notes        
Liabilities:        
Long-term Debt, Gross 100.0 100.0    
Additional disclosures        
Stated interest rate     4.60%  
Level 1        
Assets:        
Cash and cash equivalents 56.0 66.0    
Investments in rabbi trust 4.3 4.3    
Derivative instruments 0.0 0.0    
Liabilities:        
Derivative instruments 0.0 0.0    
Level 1 | $150 senior unsecured notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 154.9 161.2    
Level 1 | Line of Credit [Member]        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Level 1 | $180 term loan        
Liabilities:        
Debt Instrument, Fair Value Disclosure   0.0    
Level 1 | $100 Series A Notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Level 2        
Assets:        
Cash and cash equivalents 0.0 0.0    
Investments in rabbi trust 0.0 0.0    
Derivative instruments 1.9 3.8    
Liabilities:        
Derivative instruments 2.2 2.3    
Level 2 | $150 senior unsecured notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Level 2 | Line of Credit [Member]        
Liabilities:        
Debt Instrument, Fair Value Disclosure 95.7 68.0    
Level 2 | $180 term loan        
Liabilities:        
Debt Instrument, Fair Value Disclosure   148.5    
Level 2 | $100 Series A Notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 102.4 106.7    
Level 3        
Assets:        
Cash and cash equivalents 0.0 0.0    
Investments in rabbi trust 0.0 0.0    
Derivative instruments 0.0 0.0    
Liabilities:        
Derivative instruments 0.0 0.0    
Level 3 | $150 senior unsecured notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Level 3 | Line of Credit [Member]        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Level 3 | $180 term loan        
Liabilities:        
Debt Instrument, Fair Value Disclosure   0.0    
Level 3 | $100 Series A Notes        
Liabilities:        
Debt Instrument, Fair Value Disclosure 0.0 0.0    
Carrying Value        
Assets:        
Cash and cash equivalents 56.0 66.0    
Investments in rabbi trust 4.3 4.3    
Derivative instruments 1.9 3.8    
Liabilities:        
Derivative instruments $ 2.2 $ 2.3