Summary of Significant Accounting Policies - Non-cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Significant Noncash Transactions [Line Items]
Accounts payable related to construction in progress	$ 13,300	$ 31,600	$ 25,700
Dividends declared	75,245	68,604	61,500
Mortgages assumed from acquisitions	0	33,700	293,300
Issuance of Operating Partnership Units ("OP Units")	0	0	18,300
Redemption of OP Units	0	18,300	0
Elimination of a previously held equity interest	0	1,400	2,500
Preferred equity interest and mezzanine loan applied to purchase price of acquired properties	0	0	51,800
Reclassification adjustment of foreign currency translation			21,755
Write-off of preferred share original issuance costs	0	0	1,943
Accumulated Other Comprehensive Loss [Member]
Other Significant Noncash Transactions [Line Items]
Reclassification adjustment of foreign currency translation	$ 0	$ 0	$ 21,800