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Income Taxes - Additional Information (Detail) - USD ($)
3 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Income Taxes [Line Items]          
Minimum Distribution Percentage of Taxable Income to Qualify for Real Estate Investment Trust     90.00%    
TCJA enacted date     Dec. 22, 2017    
U.S. federal corporate tax rate     21.00% 21.00% 35.00%
TCJA one time transition tax     $ 0    
Effect of change in income tax associated with the ACT $ 1,000,000.0 $ 4,500,000      
Effective tax rate     4.00% 5.00% 7.20%
Liabilities for uncertain tax positions     $ 0 $ 0