Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Income tax expense	$ 1,000,000	$ 10,000,000
Percentage of adjusted taxable income	50.00%	50.00%	30.00%	30.00%
Built-in gains tax expense from assets sold		$ 12,000,000
Non-U.S. income tax expense		14,000,000
Income tax benefit partially offset by TRS		17,000,000
U.S. Federal Tax [Member] | REIT [Member]
Income Taxes [Line Items]
Income tax expense	$ 0	$ 0