Loans Payable - Summary of Loans Payable (Details) - USD ($) | Apr. 12, 2016 | Jun. 30, 2017 | Apr. 30, 2017 | Jun. 30, 2017 | Jun. 14, 2017 | May 03, 2017 | May 01, 2017 | Mar. 22, 2017 | Dec. 31, 2016 | Jul. 11, 2016 | Apr. 28, 2016 |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgages and other indebtedness | | $ 305,018,000 | | $ 305,018,000 | | | | | $ 305,973,000 | | |
Secured debt, gross of unamortized debt issuance cost | | 311,438,000 | | 311,438,000 | | | | | 313,698,000 | | |
Deferred Finance Costs, Net | | $ (6,420,000) | | $ (6,420,000) | | | | | (7,725,000) | | |
Revere Loan | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 8.00% | | 8.00% | | | | | | | |
Mortgages and other indebtedness | | $ 6,833,000 | | $ 6,833,000 | | | | | 7,450,000 | | |
Line of Credit | KeyBank | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 0.00% | | 0.00% | | | | | | | |
Mortgages and other indebtedness | | $ 68,032,000 | | $ 68,032,000 | | | | | 74,077,000 | | |
Line of Credit | KeyBank | LIBOR | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Debt Instrument, Basis Spread on Variable Rate | 5.00% | | | 2.50% | | | | | | | |
Senior Convertible Notes | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Interest Rate | | | | | | | | | | | 9.00% |
Mortgages and other indebtedness | | | | | | | | | | | $ 3,000,000 |
Walnut Hill Plaza | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 24,273 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.50% | | 5.50% | | | | | | | |
Mortgages and other indebtedness | | | | | | | | | 3,440,000 | | |
Monarch Bank Line Of Credit | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.25% | | 4.25% | | | | | | | |
Mortgages and other indebtedness | | $ 3,000,000 | | $ 3,000,000 | | | | | 3,000,000 | | |
Columbia Fire House | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 8.00% | | 8.00% | | | | | | | |
Mortgages and other indebtedness | | $ 254,000 | | $ 254,000 | | $ 262,000 | | | 487,000 | | |
Monarch Bank Building | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 9,473 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.15% | | 4.15% | | | | | | | |
Mortgages and other indebtedness | | $ 1,290,000 | | $ 1,290,000 | | | | | 1,320,000 | | |
Shoppes at Eagle Harbor | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 25,100 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.34% | | 4.34% | | | | | | | |
Mortgages and other indebtedness | | $ 3,418,000 | | $ 3,418,000 | | | | | 3,492,000 | | |
Revere Loan | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | $ 167,000 | $ 450,000 | | | | | | | | |
Mortgages and other indebtedness | | | | | | | $ 7,450,000 | | | | |
Lumber River | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 0.00% | | 0.00% | | | | | | | |
Mortgages and other indebtedness | | $ 1,500,000 | | $ 1,500,000 | | | | | 1,500,000 | | |
Lumber River | LIBOR | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Debt Instrument, Basis Spread on Variable Rate | | | | 2.95% | | | | | | | |
Senior Convertible Notes | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 9.00% | | 9.00% | | | | | | | |
Mortgages and other indebtedness | | $ 1,369,000 | | $ 1,369,000 | | | | | 1,400,000 | | |
Harbor Point | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 11,024 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.85% | | 5.85% | | | | | | | |
Mortgages and other indebtedness | | $ 602,000 | | $ 602,000 | | | | | 649,000 | | |
Perimeter Square | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.50% | | 5.50% | 5.50% | | | | | | |
Mortgages and other indebtedness | | $ 5,208,000 | | $ 5,208,000 | $ 4,500,000 | | | | 4,500,000 | | |
Riversedge North | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 8,802 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 6.00% | | 6.00% | | | | | | | |
Mortgages and other indebtedness | | $ 889,000 | | $ 889,000 | | | | | 914,000 | | |
DF I-Moyock | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 10,665 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.00% | | 5.00% | | | | | | | |
Mortgages and other indebtedness | | $ 253,000 | | $ 253,000 | | | | | 309,000 | | |
Rivergate | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | $ 1,520,000 | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 0.00% | | 0.00% | | | | | | | |
Mortgages and other indebtedness | | $ 22,689,000 | | $ 22,689,000 | | | | | 24,213,000 | | |
Rivergate | LIBOR | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Debt Instrument, Basis Spread on Variable Rate | | | | 2.95% | | | | | | | |
LaGrange Marketplace | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 15,065 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 0.00% | | 0.00% | | | | | | | |
Mortgages and other indebtedness | | $ 2,344,000 | | $ 2,344,000 | | | | | 2,369,000 | | |
LaGrange Marketplace | LIBOR | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Debt Instrument, Basis Spread on Variable Rate | | | | 3.75% | | | | | | | |
Folly Road | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.00% | | 4.00% | | | | 4.00% | | | |
Mortgages and other indebtedness | | $ 6,181,000 | | $ 6,181,000 | | | | $ 8,570,000 | 0 | | |
Folly Road | Line of Credit | KeyBank | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgages and other indebtedness | | | | | | | | | | $ 6,050,000 | |
Columbia Fire House construction loan | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.00% | | 4.00% | | 4.00% | | | | | |
Mortgages and other indebtedness | | $ 587,000 | | $ 587,000 | | $ 4,300,000 | | | 0 | | |
Shoppes at TJ Maxx | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 33,880 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 3.88% | | 3.88% | | | | | | | |
Mortgages and other indebtedness | | $ 5,818,000 | | $ 5,818,000 | | | | | 5,908,000 | | |
Twin City Commons | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 17,827 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.86% | | 4.86% | | | | | | | |
Mortgages and other indebtedness | | $ 3,140,000 | | $ 3,140,000 | | | | | 3,170,000 | | |
Tampa Festival | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 50,797 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.56% | | 5.56% | | | | | | | |
Mortgages and other indebtedness | | $ 8,436,000 | | $ 8,436,000 | | | | | 8,502,000 | | |
Forrest Gallery | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 50,973 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.40% | | 5.40% | | | | | | | |
Mortgages and other indebtedness | | $ 8,736,000 | | $ 8,736,000 | | | | | 8,802,000 | | |
South Carolina Food Lions Note | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 68,320 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 5.25% | | 5.25% | | | | | | | |
Mortgages and other indebtedness | | $ 12,138,000 | | $ 12,138,000 | | | | | 12,224,000 | | |
Cypress Shopping Center | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 34,360 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.70% | | 4.70% | | | | | | | |
Mortgages and other indebtedness | | $ 6,535,000 | | $ 6,535,000 | | | | | 6,585,000 | | |
Port Crossing | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 34,788 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.84% | | 4.84% | | | | | | | |
Mortgages and other indebtedness | | $ 6,317,000 | | $ 6,317,000 | | | | | 6,370,000 | | |
Freeway Junction | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 41,798 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.60% | | 4.60% | | | | | | | |
Mortgages and other indebtedness | | $ 8,057,000 | | $ 8,057,000 | | | | | 8,119,000 | | |
Harrodsburg Marketplace | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 19,112 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.55% | | 4.55% | | | | | | | |
Mortgages and other indebtedness | | $ 3,585,000 | | $ 3,585,000 | | | | | 3,617,000 | | |
Graystone Crossing | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 20,386 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.55% | | 4.55% | | | | | | | |
Mortgages and other indebtedness | | $ 3,959,000 | | $ 3,959,000 | | | | | 3,990,000 | | |
Bryan Station | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 23,489 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.52% | | 4.52% | | | | | | | |
Mortgages and other indebtedness | | $ 4,583,000 | | $ 4,583,000 | | | | | 4,619,000 | | |
Crockett Square | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.47% | | 4.47% | | | | | | | |
Mortgages and other indebtedness | | $ 6,338,000 | | $ 6,338,000 | | | | | 6,338,000 | | |
Pierpont Centre | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.15% | | 4.15% | | | | | | | |
Mortgages and other indebtedness | | $ 8,113,000 | | $ 8,113,000 | | | | | 8,450,000 | | |
Alex City Marketplace | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 3.95% | | 3.95% | | | | | | | |
Mortgages and other indebtedness | | $ 5,750,000 | | $ 5,750,000 | | | | | 5,750,000 | | |
Butler Square | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 3.90% | | 3.90% | | | | | | | |
Mortgages and other indebtedness | | $ 5,640,000 | | $ 5,640,000 | | | | | 5,640,000 | | |
Brook Run Shopping Center | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.08% | | 4.08% | | | | | | | |
Mortgages and other indebtedness | | $ 10,950,000 | | $ 10,950,000 | | | | | 10,950,000 | | |
Beaver Ruin Village I and II | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.73% | | 4.73% | | | | | | | |
Mortgages and other indebtedness | | $ 9,400,000 | | $ 9,400,000 | | | | | 9,400,000 | | |
Sunshine Shopping Plaza | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.57% | | 4.57% | | | | | | | |
Mortgages and other indebtedness | | $ 5,900,000 | | $ 5,900,000 | | | | | 5,900,000 | | |
Barnett Portfolio | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.30% | | 4.30% | | | | | | | |
Mortgages and other indebtedness | | $ 8,770,000 | | $ 8,770,000 | | | | | 8,770,000 | | |
Fort Howard Shopping Center | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.57% | | 4.57% | | | | | | | |
Mortgages and other indebtedness | | $ 7,100,000 | | $ 7,100,000 | | | | | 7,100,000 | | |
Conyers Crossing | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.67% | | 4.67% | | | | | | | |
Mortgages and other indebtedness | | $ 5,960,000 | | $ 5,960,000 | | | | | 5,960,000 | | |
Grove Park Shopping Center | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.52% | | 4.52% | | | | | | | |
Mortgages and other indebtedness | | $ 3,800,000 | | $ 3,800,000 | | | | | 3,800,000 | | |
Parkway Plaza | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.57% | | 4.57% | | | | | | | |
Mortgages and other indebtedness | | $ 3,500,000 | | $ 3,500,000 | | | | | 3,500,000 | | |
Winslow Plaza | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.82% | | 4.82% | | | | | | | |
Mortgages and other indebtedness | | $ 4,620,000 | | $ 4,620,000 | | | | | 4,620,000 | | |
Chesapeake Square | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment | | | | $ 23,857 | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.70% | | 4.70% | | | | | | | |
Mortgages and other indebtedness | | $ 4,539,000 | | $ 4,539,000 | | | | | 4,578,000 | | |
Sangaree/Tri-County/Berkley | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.78% | | 4.78% | | | | | | | |
Mortgages and other indebtedness | | $ 9,400,000 | | $ 9,400,000 | | | | | 9,400,000 | | |
Riverbridge | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.48% | | 4.48% | | | | | | | |
Mortgages and other indebtedness | | $ 4,000,000 | | $ 4,000,000 | | | | | 4,000,000 | | |
Franklin | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | |
Mortgage Loans Payable, Monthly Payment Interest Only | | | | Interest only | | | | | | | |
Mortgage Loans Payable, Interest Rate | | 4.93% | | 4.93% | | | | | | | |
Mortgages and other indebtedness | | $ 8,516,000 | | $ 8,516,000 | | | | | $ 8,516,000 | | |