Equity - Schedule of Other Common Stock Activities (Details) - Common Stock - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Dividend Reinvestment and Stock Purchase Plan (in shares)	983	2,021	2,762
Conversion of DownREIT units (in shares)	78	145	104
Exercise of stock options (in shares)	32	133	823
Vesting of restricted stock units (in shares)	419	529	409
Repurchase of common stock (in shares)	157	237	198