Equity - Tax Treatment of Dividends Paid (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Dividends Payable [Line Items]
Tax treatment of dividends, %	100.00%	100.00%	100.00%
Capital gains
Dividends Payable [Line Items]
Tax treatment of dividends, %	0.00%	0.00%	5.30%
Ordinary income
Dividends Payable [Line Items]
Tax treatment of dividends, %	78.00%	64.21%	52.30%
Return of capital
Dividends Payable [Line Items]
Tax treatment of dividends, %	22.00%	35.79%	42.40%