Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements (Details)

v3.8.0.1
Fair Value Measurements (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 19, 2014
Sep. 30, 2017
Sep. 30, 2016
Dec. 15, 2014
Jul. 09, 2010
$150 senior unsecured notes          
Liabilities:          
Long-term Debt, Gross   $ 149.5 $ 149.3    
Additional disclosures          
Term of debt issued   10 years      
Stated interest rate   5.50%     5.50%
Line of Credit [Member]          
Liabilities:          
Long-term Debt, Gross   $ 68.0 198.5    
$180 term loan          
Liabilities:          
Long-term Debt, Gross   148.5 162.0    
Additional disclosures          
Term of debt issued 5 years        
$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   66.0 52.0    
Investments in rabbi trust   4.3 4.0    
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   161.2 163.5    
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 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   3.8 1.4    
Liabilities:          
Derivative instruments   2.3 3.3    
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   68.0 198.5    
Level 2 | $180 term loan          
Liabilities:          
Debt Instrument, Fair Value Disclosure   148.5 162.0    
Level 2 | $100 Series A Notes          
Liabilities:          
Debt Instrument, Fair Value Disclosure   106.7 110.8    
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 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   66.0 52.0    
Investments in rabbi trust   4.3 4.0    
Derivative instruments   3.8 1.4    
Liabilities:          
Derivative instruments   2.3 3.3    
Additional disclosures          
Carrying amount of private equity limited partnerships for which fair value is not readily available   $ 1.4 $ 7.6