Income Taxes - Schedule of Per Share Distributions to Stockholders (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Common share distribution	$ 0.870000	$ 0.840000	$ 0.800000
Ordinary income	0.769535	0.520692	0.599384
Capital gains		0.000276	0.046380
Unrecaptured Sec. 1250 gain		0.000276	0.026512
Return of capital	0.100465	$ 0.319032	$ 0.154236
Allocable to next year	$ 0