Income Taxes - Summary of Taxability of Cash Distributions Paid on Common Shares (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Ordinary income	$ 2.50	$ 2.30	$ 1.39
Capital gains	0.23	0.17	0.02
Return of capital			0.09
Total	$ 2.73	$ 2.47	$ 1.50