Income Taxes - Schedule of Per Share Distributions to Stockholders (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Common share distribution	$ 0.900000	$ 0.870000	$ 0.840000
Ordinary income	0.619368	0.769535	0.520692
Capital gains	0.102552		0.000276
Unrecaptured Sec. 1250 gain	0.045432		0.000276
Return of capital	$ 0.178080	$ 0.100465	$ 0.319032