Equity - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended	1 Months Ended
	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	May 30, 2014 Class H Preferred Shares [Member]	Jun. 30, 2014 Class H Preferred Shares [Member]	May 30, 2014 Class H Depositary Share [Member]
Schedule Of Capitalization Equity [Line Items]
Common shares issued		0.7
Weighted-average price per share		$ 17.81
Net Proceeds		$ 11,800,000
Preferred stock redemption value						55,000,000
Cumulative redeemable preferred shares total redemption price per share						$ 504.6094		$ 25.2305
Cumulative redeemable preferred shares share redemption price per share						$ 500		$ 25.00
Redeemable preferred stock dividend per share prorated to redemption date						$ 4.6094		$ 0.2305
Write-off of preferred share original issuance costs		$ 0	$ 0	$ 1,943,000	$ 5,246,000		$ 1,900,000
Number of OP Units issued	1.0