Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.4
Fair Value Measurements - Schedule of financial assets and liabilities (Details) - USD ($)
Dec. 31, 2020
Sep. 30, 2020
Nov. 21, 2019
Assets:      
Cash and cash equivalents $ 265,800,000 $ 302,200,000  
Investments in rabbi trust 4,400,000 3,900,000  
Derivative instruments 4,800,000 2,600,000  
Liabilities:      
Derivative instruments 1,300,000 1,600,000  
Level 1      
Assets:      
Cash and cash equivalents 265,800,000 302,200,000  
Investments in rabbi trust 4,400,000 3,900,000  
Derivative instruments 0 0  
Liabilities:      
Derivative instruments 0 0  
Level 2      
Assets:      
Cash and cash equivalents 0 0  
Investments in rabbi trust 0 0  
Derivative instruments 4,800,000 2,600,000  
Liabilities:      
Derivative instruments 1,300,000 1,600,000  
Level 3      
Assets:      
Cash and cash equivalents 0 0  
Investments in rabbi trust 0 0  
Derivative instruments 0 0  
Liabilities:      
Derivative instruments 0 0  
$900.0 revolving credit facility (excluding outstanding letters of credit)      
Liabilities:      
Debt instruments 63,000,000.0    
$900.0 revolving credit facility (excluding outstanding letters of credit) | Level 1      
Liabilities:      
Debt instruments 0    
$900.0 revolving credit facility (excluding outstanding letters of credit) | Level 2      
Liabilities:      
Debt instruments 63,000,000.0    
$900.0 revolving credit facility (excluding outstanding letters of credit) | Level 3      
Liabilities:      
Debt instruments 0    
$500.0 term loan      
Liabilities:      
Debt instruments 468,700,000 475,000,000.0  
$500.0 term loan | Level 1      
Liabilities:      
Debt instruments 0 0  
$500.0 term loan | Level 2      
Liabilities:      
Debt instruments 468,700,000 475,000,000.0  
$500.0 term loan | Level 3      
Liabilities:      
Debt instruments 0 0  
Senior Unsecured Debt, Three Hundred Seventy Million [Member]      
Liabilities:      
Debt instrument, face amount 400,000,000.0    
Term Loan Facility, Two Hundred Twenty-Five Million [Member]      
Liabilities:      
Debt instruments   213,700,000  
Term Loan Facility, Two Hundred Twenty-Five Million [Member] | Level 1      
Liabilities:      
Debt instruments   0  
Term Loan Facility, Two Hundred Twenty-Five Million [Member] | Level 2      
Liabilities:      
Debt instruments   213,700,000  
Term Loan Facility, Two Hundred Twenty-Five Million [Member] | Level 3      
Liabilities:      
Debt instruments   0  
Senior Unsecured Debt, One Hundred Fifty Million [Member]      
Liabilities:      
Debt instrument, face amount 375,000,000.0    
$100.0 Series A Notes      
Liabilities:      
Debt instruments 100,000,000.0 100,000,000.0  
$100.0 Series A Notes | Level 1      
Liabilities:      
Debt instruments 0 0  
$100.0 Series A Notes | Level 2      
Liabilities:      
Debt instruments 104,600,000 105,300,000  
$100.0 Series A Notes | Level 3      
Liabilities:      
Debt instruments 0 0  
Term Loan [Member] | Term Loan 500 Million [Member]      
Liabilities:      
Debt instrument, face amount     $ 500,000,000.0
Term Loan [Member] | Term Loan 225 Million [Member]      
Liabilities:      
Debt instrument, face amount 225,000,000.0   $ 225,000,000.0
Term Loan Facility, Three Hundred Seventy-Five Million      
Liabilities:      
Debt instruments 374,500,000 374,500,000  
Term Loan Facility, Three Hundred Seventy-Five Million | Level 1      
Liabilities:      
Debt instruments 421,000,000.0 409,000,000.0  
Term Loan Facility, Three Hundred Seventy-Five Million | Level 2      
Liabilities:      
Debt instruments 0 0  
Term Loan Facility, Three Hundred Seventy-Five Million | Level 3      
Liabilities:      
Debt instruments 0 0  
Term Loan Facility, Four Hundred Million      
Liabilities:      
Debt instruments 400,000,000.0 400,000,000.0  
Term Loan Facility, Four Hundred Million | Level 1      
Liabilities:      
Debt instruments 433,900,000 429,000,000.0  
Term Loan Facility, Four Hundred Million | Level 2      
Liabilities:      
Debt instruments 0 0  
Term Loan Facility, Four Hundred Million | Level 3      
Liabilities:      
Debt instruments 0 0  
Foreign Exchange Forward | Cash flow hedging      
Liabilities:      
Derivative, notional amount $ 224,700,000 $ 232,800,000