Equity - Dividends Per Share and Distribution Per Unit Declared (Details) - $ / shares													12 Months Ended
	Nov. 02, 2017	Aug. 04, 2017	May 05, 2017	Feb. 02, 2017	Nov. 03, 2016	Aug. 04, 2016	May 02, 2016	Jan. 31, 2016	Nov. 06, 2015	Aug. 06, 2015	May 08, 2015	Jan. 28, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Tax treatment of capital gain dividends, percent													100.00%	100.00%	100.00%
Dividend Per Share/Distribution Per Unit (in dollars per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.76	$ 0.72	$ 0.68