Real Estate Investments Business Acquisitions (Details) shares in Thousands		3 Months Ended
	Mar. 01, 2017 USD ($) property shares	Mar. 31, 2017 USD ($) a shares	Mar. 31, 2016 USD ($)
Business Acquisition [Line Items]
Purchase Price		$ 9,500,000	$ 35,294,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		0	$ 0
Equity One Inc. [Member]
Business Acquisition [Line Items]
Number of real estate properties acquired | property	121
Shares of common stock issued for merger (in shares) | shares	65,495
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ 1,509,212,000
Intangible assets	$ 500,645,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		$ 34,936,000
Garden City [Member]
Business Acquisition [Line Items]
Date Purchased		Mar. 06, 2017
Property Name		The Field at Commonwealth
City/State		Chantilly, VA
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Purchase Price		$ 9,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		$ 0
The Market at Springwoods Village [Member]
Business Acquisition [Line Items]
Date Purchased			Mar. 04, 2016
Property Name			The Market at Springwoods Village (1)
City/State			Houston, TX
Business Acquisition, Percentage of Voting Interests Acquired			53.00%
Purchase Price			$ 17,994,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities			0
Non-controlling interest recorded, fair value			$ 8,400,000
Pinecrest Place [Member] [Member]
Business Acquisition [Line Items]
Land Subject to Ground Leases | a		10.67
Date Purchased		Mar. 08, 2017
Property Name		Pinecrest Place (1)
City/State		Miami, FL
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Purchase Price		$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		$ 0
Garden City [Member]
Business Acquisition [Line Items]
Date Purchased			Feb. 22, 2016
Property Name			Garden City Park
City/State			Garden City Park, NY
Business Acquisition, Percentage of Voting Interests Acquired			100.00%
Purchase Price			$ 17,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities			0
Parent Company [Member]
Business Acquisition [Line Items]
Conversion of Stock, Conversion Ratio		0.45
Shares of common stock issued for merger (in shares) | shares		65,500
Partially Owned Properties [Member] | Equity One Inc. [Member]
Business Acquisition [Line Items]
Number of real estate properties acquired | property	8
Off-Market Favorable Lease [Member]
Business Acquisition [Line Items]
Intangible assets		$ 0	10,171,000
Off-Market Favorable Lease [Member] | Garden City [Member]
Business Acquisition [Line Items]
Intangible assets		0
Off-Market Favorable Lease [Member] | The Market at Springwoods Village [Member]
Business Acquisition [Line Items]
Intangible assets			0
Off-Market Favorable Lease [Member] | Pinecrest Place [Member] [Member]
Business Acquisition [Line Items]
Intangible assets		0
Off-Market Favorable Lease [Member] | Garden City [Member]
Business Acquisition [Line Items]
Intangible assets			10,171,000
Off-Market Lease, Unfavorable [Member]
Business Acquisition [Line Items]
Intangible assets		0	2,940,000
Off-Market Lease, Unfavorable [Member] | Garden City [Member]
Business Acquisition [Line Items]
Intangible assets		0
Off-Market Lease, Unfavorable [Member] | The Market at Springwoods Village [Member]
Business Acquisition [Line Items]
Intangible assets			0
Off-Market Lease, Unfavorable [Member] | Pinecrest Place [Member] [Member]
Business Acquisition [Line Items]
Intangible assets		$ 0
Off-Market Lease, Unfavorable [Member] | Garden City [Member]
Business Acquisition [Line Items]
Intangible assets			$ 2,940,000