Related Party Transactions (Details)
 2 Months Ended 10 Months Ended 12 Months Ended
Dec. 15, 2017
USD ($)
Sep. 30, 2018
USD ($)
shares
Sep. 30, 2018
USD ($)
director
shares
Sep. 30, 2017
USD ($)
shares
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Sep. 30, 2014
USD ($)
Mar. 27, 2014
Related Party Transaction [Line Items]                
Number of directors | director     7          
Preferred shares issued | shares   0 0          
Koopid Inc                
Related Party Transaction [Line Items]                
Cost of goods and services sold   $ 1,000,000            
Messrs. Mohebbi and Rittenmeyer                
Related Party Transaction [Line Items]                
Amount of transaction     $ 800,000          
NES acquisition | Series A Preferred Stock | Tpg Capital                
Related Party Transaction [Line Items]                
Preferred shares issued | shares       38,865        
NES acquisition | Series A Preferred Stock | Silver Lake Partners                
Related Party Transaction [Line Items]                
Preferred shares issued | shares       38,865        
NES acquisition | Series B Preferred Stock | Tpg Capital                
Related Party Transaction [Line Items]                
Preferred shares issued | shares       16,273        
NES acquisition | Series B Preferred Stock | Silver Lake Partners                
Related Party Transaction [Line Items]                
Preferred shares issued | shares       16,273        
Tenet Healthcare | Director                
Related Party Transaction [Line Items]                
Revenue from related parties   1,000,000            
Sales Of Products And Services To American International Group, Inc. | Director                
Related Party Transaction [Line Items]                
Revenue from related parties   5,000,000            
Predecessor | Koopid Inc                
Related Party Transaction [Line Items]                
Cost of goods and services sold $ 0     $ 0 $ 0      
Predecessor | Messrs. Mohebbi and Rittenmeyer                
Related Party Transaction [Line Items]                
Reduction of related party transaction, amount           $ 800,000    
Predecessor | The Sponsors                
Related Party Transaction [Line Items]                
Cost of goods and services sold 15,000,000     10,000,000 13,000,000      
Revenue from related parties 10,000,000     29,000,000 33,000,000      
Predecessor | Commerical Real Estate Services Firm                
Related Party Transaction [Line Items]                
Cost of goods and services sold 5,000,000     5,000,000 8,000,000      
Predecessor | Accenture                
Related Party Transaction [Line Items]                
Revenue from related parties 0     1,000,000 1,000,000      
Predecessor | Sungard                
Related Party Transaction [Line Items]                
Cost of goods and services sold 0     1,000,000 1,000,000      
Predecessor | C3                
Related Party Transaction [Line Items]                
Revenue from related parties 0     1,000,000 1,000,000      
Predecessor | Xirrus                
Related Party Transaction [Line Items]                
Cost of goods and services sold 0     12,000,000 14,000,000      
Predecessor | Ciena                
Related Party Transaction [Line Items]                
Cost of goods and services sold 0     1,000,000 1,000,000      
Predecessor | Tenet Healthcare | Director                
Related Party Transaction [Line Items]                
Revenue from related parties 0     1,000,000 2,000,000      
Predecessor | Sales Of Products And Services To American International Group, Inc. | Director                
Related Party Transaction [Line Items]                
Revenue from related parties 2,000,000     10,000,000 14,000,000      
Predecessor | Stockholders', Registration Rights And Management Services Agreements | Affiliated Entity                
Related Party Transaction [Line Items]                
Amount of transaction 0              
Flex Ltd | Affiliated Entity                
Related Party Transaction [Line Items]                
Accounts payable, related parties   4,000,000 4,000,000          
Flex Ltd | Purchased Goods And Services From Flex Ltd. | Board of Directors Chairman                
Related Party Transaction [Line Items]                
Cost of goods and services sold   $ 19,000,000            
Flex Ltd | Predecessor | Affiliated Entity                
Related Party Transaction [Line Items]                
Accounts payable, related parties       7,000,000        
Flex Ltd | Predecessor | Purchased Goods And Services From Flex Ltd. | Board of Directors Chairman                
Related Party Transaction [Line Items]                
Cost of goods and services sold 6,000,000     38,000,000 113,000,000      
Silver Lake Management Company L.L.C. | Predecessor | Affiliated Entity                
Related Party Transaction [Line Items]                
Management fee $ 0     $ 2,000,000 7,000,000      
Silver Lake Management Company L.L.C. | Predecessor | Monitoring Fee | Affiliated Entity                
Related Party Transaction [Line Items]                
Amount of transaction     $ 7,000,000          
TPG Capital Management LP | Predecessor | Monitoring Fee | Affiliated Entity                
Related Party Transaction [Line Items]                
Reduction of related party transaction, amount             $ 1,325,000  
Xiirus Inc | Predecessor                
Related Party Transaction [Line Items]                
Ownership percentage (less than)               6.00%
Payments to acquire equity method investments         1,000,000      
Income (loss) from equity method investments         $ (11,000,000)      
Non-Employee Director                
Related Party Transaction [Line Items]                
Number of directors | director     6