Nature of Business and Financial Statement Presentation - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) JointVenture $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2016 USD ($)
Nature Of Business And Financial Statement Presentation [Line Items]
Maximum exposure to losses associated with VIEs | $	$ 329.5		$ 405.4
Common share dividends declared per share | $ / shares	$ 0.19	$ 0.19
Percentage of lease commission income upon lease execution	50.00%
Percentage of lease commission income upon tenant rent commencement	50.00%
Variable Interest Entity, Not Primary Beneficiary [Member]
Nature Of Business And Financial Statement Presentation [Line Items]
Number of unconsolidated joint ventures | JointVenture	2