Income Taxes - Schedule of Cash Distributions to Stockholders for Federal Income Tax Purposes (Detail) - Common Stock [member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Ordinary dividends	$ 1.61	$ 1.64
Capital gain distributions	$ 0.29	$ 1.32