Equity - Tax Treatment of Dividends Paid (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Dividends Payable [Line Items]
Tax treatment of dividends, %	100.00%	100.00%
Capital Gains [Member]
Dividends Payable [Line Items]
Tax treatment of dividends, %	5.30%
Ordinary Income [Member]
Dividends Payable [Line Items]
Tax treatment of dividends, %	52.30%	17.00%
Return of Capital [Member]
Dividends Payable [Line Items]
Tax treatment of dividends, %	42.40%	83.00%