Business Combinations (Textual) (Details)		12 Months Ended
	Dec. 01, 2016 USD ($) Communities properties $ / shares shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Business Combinations, Other Consideration	$ 2,000,000
Business Combination, Merger and Integration Related Expenses			$ 20,000,000	$ 40,800,000
Redeemable Preferred Stock [Member]
Business Acquisition [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	14.24
Mandatorily Redeemable Preferred Stock, Fair Value Disclosure	$ 77.02
Preferred Stock, Shares Outstanding | shares	867,846
Unsecured Debt
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Other	$ 300,000,000
Line of Credit [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Other	$ 162,000,000
Parent Company [Member]
Business Acquisition [Line Items]
Common Stock, Conversion Basis		0.71
Business Combination, Merger and Integration Related Expenses		$ 9,112,000	$ 19,990,000	$ 40,823,000
Preferred Stock, Shares Outstanding | shares		867,846	867,846
Parent Company [Member] | Post [Member] [Domain]
Business Acquisition [Line Items]
Number of Apartment Communities Acquired in Real Estate Property | Communities	61
Number of Commercial Properties Acquired in Real Estate Property | properties	4
Acquired properties, purchase price	$ (4,006,586,000)
Share Price | $ / shares	$ 91.41
Stock Issued During Period, Shares, Acquisitions | shares	38,000,000
Noncontrolling Interest
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares	80,000
Business Combination, Separately Recognized Transactions [Domain]
Business Acquisition [Line Items]
Business Combination, Merger and Integration Related Expenses		$ 9,100,000