Equity - Dividends Per Share and Distribution Per Unit Declared (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Dividends Payable [Line Items]
Dividend Per Share/Distribution Per Unit	$ 0.64	$ 0.40
Installment 1-FY2014 [Member]
Dividends Payable [Line Items]
Declaration Date	Feb. 18, 2014
Record Date	Apr. 01, 2014
Paid Date	Apr. 10, 2014
Dividend Per Share/Distribution Per Unit	$ 0.16
Installment 2-FY2014 [Member]
Dividends Payable [Line Items]
Declaration Date	May 09, 2014
Record Date	Jul. 01, 2014
Paid Date	Jul. 10, 2014
Dividend Per Share/Distribution Per Unit	$ 0.16
Installment 3-FY2014 [Member]
Dividends Payable [Line Items]
Declaration Date	Aug. 04, 2014
Record Date	Oct. 01, 2014
Paid Date	Oct. 09, 2014
Dividend Per Share/Distribution Per Unit	$ 0.16
Installment 4-FY2014 [Member]
Dividends Payable [Line Items]
Declaration Date	Nov. 10, 2014
Record Date	Dec. 30, 2014
Paid Date	Jan. 08, 2015
Dividend Per Share/Distribution Per Unit	$ 0.16
Installment 1-FY2013 [Member]
Dividends Payable [Line Items]
Declaration Date	Jun. 19, 2013
Record Date	Jul. 01, 2013
Paid Date	Jul. 11, 2013
Dividend Per Share/Distribution Per Unit		$ 0.08
Installment 2-FY2013 [Member]
Dividends Payable [Line Items]
Declaration Date	Aug. 09, 2013
Record Date	Oct. 01, 2013
Paid Date	Oct. 10, 2013
Dividend Per Share/Distribution Per Unit		$ 0.16
Installment 3-FY2013 [Member]
Dividends Payable [Line Items]
Declaration Date	Nov. 11, 2013
Record Date	Dec. 30, 2013
Paid Date	Jan. 09, 2014
Dividend Per Share/Distribution Per Unit		$ 0.16