Annual report pursuant to Section 13 and 15(d)

Noncontrolling Interests in Subsidiaries - Additional Information (Detail)

v3.20.4
Noncontrolling Interests in Subsidiaries - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Noncontrolling Interest [Abstract]      
Changes in ownership interest in subsidiaries $ 0 $ 0 $ 0