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Prepaid Expenses and Other Assets - Additional Information (Detail) - Partnership Agreement [Member] - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Jun. 30, 2016
Jun. 30, 2019
Prepaid expenses and other assets [Line Items]            
Partnership agreement         10 years  
Upfront cash payment         $ 10.0  
Prepaid expenses and other assets $ 1.0   $ 1.0     $ 1.0
Other assets, noncurrent 4.7   4.7     $ 5.3
Amortization expense $ 0.3 $ 0.3 $ 0.6 $ 0.6