Non-Controlling Interests, Preferred Shares, Common Shares and Common Shares in Treasury - Common Shares Through Open Market Sales (Detail) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity [Abstract]
Number of Shares Sold	0.7	44.1	36.5
Average Price Per Share	$ 18.15	$ 18.76	$ 13.98
Net Proceeds	$ 11,635	$ 788,045	$ 492,129