Mortgages and Loans Payable (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014 Properties		Sep. 30, 2013 Properties	Dec. 31, 2013
Debt Instrument [Line Items]
Outstanding Principal Balance	$ 510,136,000	[1]		$ 510,136,000	[1]
Acquired below market lease intangibles, net of accumulated amortization	36,520,000			36,520,000			20,387,000
Below Market Lease, Accumulated Amortization	6,101,000			6,101,000			2,708,000
Outstanding mortgage notes payable maturing in 2014	6,400,000	[1],[2],[3],[4]		6,400,000	[1],[2],[3],[4]
Weighted-average interest rate on debt	4.34%			4.34%			5.61%
Real estate properties acquired with assumed debt				15		8
Debt assumed from real estate acquisitions				183,500,000		90,300,000
Business Acquisition During Period, Cost of Acquired Entity, Fair Value of Debt Assumed				189,000,000		93,900,000
Amortization on assumed below-market debt adjustment	600,000		400,000	1,800,000		800,000
Fixed Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Outstanding Principal Balance	359,136,000	[1],[2],[3],[5]		359,136,000	[1],[2],[3],[5]		196,052,000	[2],[5]
Weighted-average interest rate on debt	5.50%	[2],[3]		5.50%	[2],[3]
Revolving Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit facility, borrowing capacity	350,000,000			350,000,000
Credit facility, maximum potential borrowing capacity	600,000,000			600,000,000
Credit facility, outstanding principal balance	151,000,000			151,000,000
Credit facility, current borrowing capacity	$ 217,000,000			$ 217,000,000
Debt instrument, number of extension options	2			2
Revolving Credit Facility [Member] | Unsecured Debt [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				1.30%

[1] The debt maturity table does not include any below-market debt adjustment, of which $8.5 million, net of accumulated amortization, was outstanding as of September 30, 2014.

[2] As of September 30, 2014, the interest rate on $11.7 million outstanding under one of our variable-rate mortgage notes payable was, in effect, fixed at 5.22% by an interest rate swap agreement (see Notes 4 and 10).

[3] All but $6.4 million of the fixed-rate debt represents loans assumed as part of certain acquisitions.

[4] Includes only October 1, 2014 through December 31, 2014. Of the $8.2 million, $6.4 million is for principal payment obligations on a loan that was repaid subsequent to September 30, 2014 and $1.8 million is for principal payment obligations on loans that mature after 2014.

[5] Due to the non-recourse nature of certain mortgages, the assets and liabilities of the following properties are neither available to pay the debts of the consolidated limited liability companies nor constitute obligations of the consolidated limited liability companies: Baker Hill Center, Broadway Plaza, Publix at Northridge, Kleinwood Center, Murray Landing, Vineyard Center, Sunset Center, Westwoods Shopping Center, Stockbridge Commons, East Burnside Plaza, Fresh Market, Collington Plaza, Stop & Shop Plaza, Arcadia Plaza, Savoy Plaza, Coppell Market Center, Statler Square, Hamilton Village, Waynesboro Plaza, Thompson Valley Towne Center, Lumina Commons, Driftwood Village, and Orchard Square. The outstanding principal balance of these non-recourse mortgages as of September 30, 2014 and December 31, 2013 was $259.5 million and $157.8 million, respectively.