Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies - Additional Information (Detail)

v3.19.3.a.u2
Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Sep. 30, 2019
USD ($)
reporting_unit
state
Sep. 30, 2018
USD ($)
Dec. 31, 2019
USD ($)
Summary Of Accounting Policies [Line Items]      
Revisions in estimates related to amounts recorded in prior periods for revenue $ 3,800,000 $ 6,900,000  
Amount company is liable for per occurrence $ 500,000    
Number of reporting units | reporting_unit 5    
Minimum      
Summary Of Accounting Policies [Line Items]      
Amount company is liable for per occurrence $ 100,000    
Stop-loss insurance purchased 75,000    
Maximum      
Summary Of Accounting Policies [Line Items]      
Amount company is liable for per occurrence 500,000    
Stop-loss insurance purchased $ 160,000    
Accounting Standards Update 2016-02 | Forecast | Minimum      
Summary Of Accounting Policies [Line Items]      
Operating lease, right-of-use asset     $ 9,000,000.0
Operating lease, liability     9,000,000.0
Accounting Standards Update 2016-02 | Forecast | Maximum      
Summary Of Accounting Policies [Line Items]      
Operating lease, right-of-use asset     10,000,000.0
Operating lease, liability     $ 10,000,000.0
Alabama, Florida, Georgia, North Carolina And South Carolina      
Summary Of Accounting Policies [Line Items]      
Number of states | state 4