Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of financial assets and liabilities (Details)

v3.10.0.1
Fair Value Measurements - Schedule of financial assets and liabilities (Details) - USD ($)
Jun. 30, 2018
Sep. 30, 2017
Jun. 30, 2017
Sep. 30, 2016
Dec. 19, 2014
Financial assets and liabilities at carrying value and fair value          
Cash and cash equivalents $ 71,100,000 $ 66,000,000 $ 71,500,000 $ 52,000,000  
Assets:          
Long-term Debt 424,400,000 465,700,000      
Level 1          
Assets:          
Cash and cash equivalents 71,100,000        
Investments in rabbi trust 4,100,000        
Derivative instruments 0        
Liabilities:          
Derivative instruments 0        
Level 2          
Assets:          
Cash and cash equivalents 0        
Investments in rabbi trust 0        
Derivative instruments 3,000,000        
Liabilities:          
Derivative instruments 2,100,000        
Level 3          
Assets:          
Cash and cash equivalents 0        
Investments in rabbi trust 0        
Derivative instruments 0        
Liabilities:          
Derivative instruments 0        
$150 senior unsecured notes          
Financial assets and liabilities at carrying value and fair value          
Debt instrument, face amount 150,000,000   150,000,000    
Assets:          
Long-term Debt, Gross 149,600,000        
Long-term Debt 149,200,000 148,900,000      
$150 senior unsecured notes | Level 1          
Liabilities:          
Debt instruments 156,200,000        
$150 senior unsecured notes | Level 2          
Liabilities:          
Debt instruments 0        
$150 senior unsecured notes | Level 3          
Liabilities:          
Debt instruments 0        
Revolving credit facility          
Assets:          
Long-term Debt, Gross 175,600,000 68,000,000      
Long-term Debt 175,600,000        
Revolving credit facility | Level 1          
Liabilities:          
Debt instruments 0        
Revolving credit facility | Level 2          
Liabilities:          
Debt instruments 175,600,000        
Revolving credit facility | Level 3          
Liabilities:          
Debt instruments 0        
Term loan          
Financial assets and liabilities at carrying value and fair value          
Debt instrument, face amount   180,000,000     $ 180,000,000.0
Assets:          
Long-term Debt, Gross 0 148,500,000      
$100 Series A Notes          
Financial assets and liabilities at carrying value and fair value          
Debt instrument, face amount 100,000,000   $ 100,000,000    
Assets:          
Long-term Debt, Gross 100,000,000        
Long-term Debt 99,600,000 99,700,000      
$100 Series A Notes | Level 1          
Liabilities:          
Debt instruments 0        
$100 Series A Notes | Level 2          
Liabilities:          
Debt instruments 100,000,000        
$100 Series A Notes | Level 3          
Liabilities:          
Debt instruments 0        
Derivatives | Cash flow hedging          
Financial assets and liabilities at carrying value and fair value          
Derivative, notional amount 190,100,000        
Reported Value Measurement          
Financial assets and liabilities at carrying value and fair value          
Cash and cash equivalents 71,100,000        
Assets:          
Investments in rabbi trust 4,100,000        
Derivative instruments 3,000,000        
Liabilities:          
Derivative instruments 2,100,000        
Trade Names [Member]          
Assets:          
Indefinite-Lived Intangible Assets (Excluding Goodwill) 127,900,000 $ 133,400,000      
Customer Concentration Risk [Member] | Trade Names [Member]          
Assets:          
Indefinite-Lived Intangible Assets (Excluding Goodwill) $ 4,000,000