Equity (Exchangeable Shares and Series F and Series G Preferred Stock) - Additional Information (Detail) - shares	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Minimum number of shares that can be exchanged by exchangeable shareholders unless the number of remaining exchangeable shares registered in the name of the holder is less	50,000
Number of shares of Common stock received for each exchangeable share	1
Common stock, shares outstanding	144,194,115	152,907,166
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Number of preferred Stock issued to voting trust	1	1
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Number of preferred Stock issued to voting trust	1	1
Exchangeable Shares [Member]
Class of Stock [Line Items]
Common stock, shares outstanding	6,876,042	6,876,042
Series F- and Series G- Preferred Stock [Member]
Class of Stock [Line Items]
Exchangeable stock shares outstanding	3,949,929