| Business Combinations  - Other Fiscal 2019 Additional Information (Details) | 3 Months Ended | ||
|---|---|---|---|
| Mar. 31, 2019  USD ($)  company | Sep. 30, 2018  USD ($)  company | Sep. 30, 2019  USD ($) | |
| Three privately-held companies | |||
| Business Acquisition | |||
| Number of companies acquired | company | 3 | ||
| Total purchase consideration | $ 118,300,000 | ||
| Additional consideration (up to) | $ 13,000,000.0 | ||
| Contingent consideration, non-current | $ 5,300,000 | ||
| Two privately-held companies | |||
| Business Acquisition | |||
| Number of companies acquired | company | 2 | ||
| Total purchase consideration | $ 15,400,000 | ||
| Additional consideration (up to) | $ 6,000,000.0 | ||
| Contingent consideration, non-current | $ 1,700,000 | ||
| X | ||||||||||
| 
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
 | 
| X | ||||||||||
| 
- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
 | 
| X | ||||||||||
| 
- Definition Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
 | 
| X | ||||||||||
| 
- Definition The number of businesses acquired by the entity during the period. No definition available. 
 | 
| X | ||||||||||
| 
- Details 
 | 
| X | ||||||||||
| 
- Details 
 |