Income Taxes - Schedule of Per Share Distributions to Stockholders (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Common share distribution	$ 1.070000	$ 1.010000	$ 0.990000
Ordinary income	0.603050	0.701910	0.438792
Capital gains		0.275040	0.551208
Unrecaptured Sec. 1250 gain		0.041160	0.132280
Section 199A Dividends	0.603050	0.701910	$ 0.438792
Return of capital	$ 0.466950	$ 0.033050