Loans Payable - Summary of Loans Payable (Details) - USD ($) | Mar. 29, 2019 | Feb. 07, 2019 | Jan. 29, 2019 | Jan. 11, 2019 | Mar. 31, 2019 | Jan. 15, 2019 | Dec. 31, 2018 |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate. stated percentage | | | | | 5.00% | | |
Loans payable, net | | | | | $ 348,651,000 | | $ 360,117,000 |
Total Principal Balance | | | | | 359,926,000 | | 369,612,000 |
Unamortized debt issuance cost | | | | | (4,735,000) | | (5,144,000) |
Total Loans Payable, including Assets Held for Sale | | | | | 355,191,000 | | 364,468,000 |
Less loans payable on assets held for sale, net loan amortization costs | | | | | 6,540,000 | | 4,351,000 |
First National Bank Line of Credit | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | 24,656 | | |
Loans payable, net | | | | | 1,379,000 | | 2,938,000 |
Lumber River | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | 10,723 | | |
Loans payable, net | | | | | $ 1,438,000 | | 1,448,000 |
Lumber River | LIBOR | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | | | 3.50% | | |
Revere Loan | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | $ 406,000 | $ 30,000 | | $ 323,000 | $ 300,000 | | |
Senior convertible notes | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 234,199 | | |
Debt instrument, interest rate. stated percentage | | | | | 9.00% | | |
Loans payable, net | | | | | $ 692,000 | | 1,369,000 |
Harbor Point | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 11,024 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.85% | | |
Perimeter Square | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 6.50% | 6.50% | |
Loans payable, net | | | | | $ 6,250,000 | $ 6,250,000 | 6,250,000 |
Perimeter Square Construction Loan | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 6.50% | | |
Loans payable, net | | | | | $ 247,000 | $ 247,000 | 247,000 |
Riversedge North | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 11,436 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.77% | | |
Loans payable, net | | | | | $ 1,791,000 | | 1,800,000 |
DF I-Moyock | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | 10,665 | | |
Loans payable, net | | | | | 43,000 | | 73,000 |
Rivergate | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | 141,230 | | |
Loans payable, net | | | | | $ 21,974,000 | | 22,117,000 |
Rivergate | LIBOR | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | | | 2.95% | | |
Folly Road | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | 32827 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.00% | | |
Loans payable, net | | | | | $ 6,035,000 | | 6,073,000 |
Columbia Fire Station | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 25,452 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.00% | | |
Loans payable, net | | | | | $ 4,154,000 | | 4,189,000 |
Shoppes at TJ Maxx | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 33,880 | | |
Debt instrument, interest rate. stated percentage | | | | | 3.88% | | |
Loans payable, net | | | | | $ 5,491,000 | | 5,539,000 |
JANAF Bravo | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | 36935 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.65% | | |
Loans payable, net | | | | | $ 6,476,000 | | 6,500,000 |
Walnut Hill Plaza | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 26,850 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.50% | | |
Loans payable, net | | | | | $ 3,840,000 | | 3,868,000 |
Twin City Commons | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 17,827 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.86% | | |
Loans payable, net | | | | | $ 3,032,000 | | 3,048,000 |
Twin City Commons | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 48,747 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.65% | | |
Loans payable, net | | | | | $ 6,859,000 | | 6,907,000 |
Shoppes at Eagle Harbor | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 53,185 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.71% | | |
Loans payable, net | | | | | $ 7,515,000 | | 7,567,000 |
New Market | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 33,340 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.71% | | |
Loans payable, net | | | | | $ 5,695,000 | | 5,713,000 |
JANAF | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 333,159 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.49% | | |
Loans payable, net | | | | | $ 51,838,000 | | 52,253,000 |
Deutsche Bank | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 50,797 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.56% | | |
Loans payable, net | | | | | $ 8,189,000 | | 8,227,000 |
JANAF | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 50,973 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.40% | | |
Loans payable, net | | | | | $ 8,491,000 | | 8,529,000 |
Forrest Gallery | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 68,320 | | |
Debt instrument, interest rate. stated percentage | | | | | 5.25% | | |
Loans payable, net | | | | | $ 11,819,000 | | 11,867,000 |
Cypress Shopping Center | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 34,360 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.70% | | |
Loans payable, net | | | | | $ 6,351,000 | | 6,379,000 |
Port Crossing | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 34,788 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.84% | | |
Loans payable, net | | | | | $ 6,120,000 | | 6,150,000 |
Freeway Junction | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 41,798 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.60% | | |
Loans payable, net | | | | | $ 7,828,000 | | 7,863,000 |
Harrodsburg Marketplace | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 19,112 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.55% | | |
Loans payable, net | | | | | $ 3,469,000 | | 3,486,000 |
Graystone Crossing | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 20,386 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.55% | | |
Loans payable, net | | | | | $ 0 | | 3,863,000 |
Bryan Station | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 23,489 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.52% | | |
Loans payable, net | | | | | $ 4,452,000 | | 4,472,000 |
Crockett Square | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.47% | | |
Loans payable, net | | | | | $ 6,338,000 | | 6,338,000 |
Pierpont Centre | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.15% | | |
Loans payable, net | | | | | $ 8,113,000 | | 8,113,000 |
Alex City Marketplace | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 3.95% | | |
Loans payable, net | | | | | $ 5,750,000 | | 5,750,000 |
Butler Square | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 3.90% | | |
Loans payable, net | | | | | $ 5,640,000 | | 5,640,000 |
Brook Run Shopping Center | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.08% | | |
Loans payable, net | | | | | $ 10,950,000 | | 10,950,000 |
Beaver Ruin Village I and II | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.73% | | |
Loans payable, net | | | | | $ 9,400,000 | | 9,400,000 |
Sunshine Shopping Plaza | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.57% | | |
Loans payable, net | | | | | $ 5,900,000 | | 5,900,000 |
Barnett Portfolio | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.30% | | |
Loans payable, net | | | | | $ 8,770,000 | | 8,770,000 |
Fort Howard Shopping Center | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.57% | | |
Loans payable, net | | | | | $ 7,100,000 | | 7,100,000 |
Conyers Crossing | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.67% | | |
Loans payable, net | | | | | $ 5,960,000 | | 5,960,000 |
Grove Park Shopping Center | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.52% | | |
Loans payable, net | | | | | $ 3,800,000 | | 3,800,000 |
Parkway Plaza | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.57% | | |
Loans payable, net | | | | | $ 3,500,000 | | 3,500,000 |
Winslow Plaza | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.82% | | |
Loans payable, net | | | | | $ 4,620,000 | | 4,620,000 |
JANAF BJ's | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 29,964 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.95% | | |
Loans payable, net | | | | | $ 5,038,000 | | 5,065,000 |
Chesapeake Square | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | | | $ 23,857 | | |
Debt instrument, interest rate. stated percentage | | | | | 4.70% | | |
Loans payable, net | | | | | $ 4,411,000 | | 4,434,000 |
Berkley/Sangaree/Tri-County | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.78% | | |
Loans payable, net | | | | | $ 9,400,000 | | 9,400,000 |
Riverbridge | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.48% | | |
Loans payable, net | | | | | $ 4,000,000 | | 4,000,000 |
Franklin | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Debt instrument, interest rate. stated percentage | | | | | 4.93% | | |
Loans payable, net | | | | | $ 8,516,000 | | 8,516,000 |
Revere Loan | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, periodic payment | | | $ 20,000 | | $ 109,658 | | |
Debt instrument, interest rate. stated percentage | | | | | 10.00% | | |
Loans payable, net | | | | | $ 0 | | 1,059,000 |
Harbor Point | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Loans payable, net | | | | | $ 0 | | 460,000 |
Line of Credit | First National Bank Line of Credit | LIBOR | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | | | 3.50% | | |
Line of Credit | KeyBank Line of Credit Maturing February 2019 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Loans payable, net | | | | | $ 2,980,000 | | 3,830,000 |
Line of Credit | KeyBank Line of Credit Maturing February 2019 | LIBOR | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | | | 2.50% | | |
Line of Credit | KeyBank Line of Credit Maturing December 2019 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, payment terms | | | | | Interest only | | |
Loans payable, net | | | | | $ 48,272,000 | | $ 48,272,000 |
Line of Credit | KeyBank Line of Credit Maturing December 2019 | LIBOR | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | | | 2.50% | | |