Non-Controlling Interests, Preferred Shares, Common Shares and Common Shares in Treasury - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Equity [Line Items]
Operating partnership units outstanding	369,176	369,176
Common shares, par value	$ 0.10	$ 0.10
Net proceeds	$ 0	$ 0	$ 11,635
Common Shares [Member]
Schedule Of Equity [Line Items]
Issuance of common shares			664,000
Average price per share			$ 18.15
Class J Depositary Share [Member]
Schedule Of Equity [Line Items]
Cumulative redeemable preferred shares liquidation value	$ 500
Redemption date restrictions for depositary shares	Aug. 01, 2017
Class K Depositary Share [Member]
Schedule Of Equity [Line Items]
Cumulative redeemable preferred shares liquidation value	$ 500
Redemption date restrictions for depositary shares	Apr. 09, 2018
Class A Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class B Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class C Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class D Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class E Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class F Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class G Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class H Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class I Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Class J Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Cumulative redeemable preferred shares liquidation value	$ 500	$ 500
Preferred Shares, without par value	750,000	750,000
Class K Cumulative Redeemable Preferred Shares [Member]
Schedule Of Equity [Line Items]
Cumulative redeemable preferred shares liquidation value	$ 500	$ 500
Preferred Shares, without par value	750,000	750,000
Non-Cumulative Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	750,000
Cumulative Voting Preferred Shares [Member]
Schedule Of Equity [Line Items]
Preferred Shares, without par value	2,000,000