Annual report pursuant to Section 13 and 15(d)

Concentration of Risk - Additional Information (Detail)

v3.19.3.a.u2
Concentration of Risk - Additional Information (Detail) - State
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Concentration Risk [Line Items]      
Number of states in which entity operates 35    
Louisiana, Tennessee, Arkansas, Mississippi, Kentucky, Florida, and Alabama | Net Service Revenue | Geographic Concentration Risk      
Concentration Risk [Line Items]      
Concentration risk percentage 53.00% 54.20% 63.00%