SEGMENT FINANCIAL INFORMATION | SEGMENT FINANCIAL INFORMATION Our three reportable segments are office, retail and industrial. Factors used to determine our reportable segments include the physical and economic characteristics of our properties and the related operating activities. Our chief operating decision makers rely primarily on net operating income to make decisions about allocating resources and assessing segment performance. Net operating income is the key performance metric that captures the unique operating characteristics of each segment. Items that are not directly assignable to a segment, such as certain corporate items, are not allocated but reflected as reconciling items. The following table reflects our total assets by business segment as of September 30, 2018 and December 31, 2017 : As of (in thousands) September 30, 2018 December 31, 2017 Assets: Office $ 721,424 $ 775,917 Retail 685,695 705,696 Industrial 93,239 58,657 Corporate 80,872 67,836 Total assets $ 1,581,230 $ 1,608,106 The following table sets forth the financial results by segment for the three and nine months ended September 30, 2018 and 2017 : (in thousands) Office Retail Industrial Consolidated Three Months Ended September 30, 2018 Rental revenues $ 28,795 $ 18,497 $ 2,213 $ 49,505 Rental expenses (10,622 ) (4,124 ) (446 ) (15,192 ) Net operating income $ 18,173 $ 14,373 $ 1,767 $ 34,313 Real estate-related depreciation and amortization $ 8,714 $ 4,935 $ 1,312 $ 14,961 Three Months Ended September 30, 2017 Rental revenues $ 27,099 $ 20,841 $ 1,538 $ 49,478 Rental expenses (11,369 ) (5,803 ) (344 ) (17,516 ) Net operating income $ 15,730 $ 15,038 $ 1,194 $ 31,962 Real estate-related depreciation and amortization $ 10,250 $ 6,022 $ 655 $ 16,927 Nine Months Ended September 30, 2018 Rental revenues $ 79,480 $ 55,387 $ 5,554 $ 140,421 Rental expenses (32,347 ) (12,934 ) (1,034 ) (46,315 ) Net operating income $ 47,133 $ 42,453 $ 4,520 $ 94,106 Real estate-related depreciation and amortization $ 24,709 $ 15,608 $ 2,885 $ 43,202 Nine Months Ended September 30, 2017 Rental revenues $ 84,163 $ 63,421 $ 4,438 $ 152,022 Rental expenses (33,910 ) (16,344 ) (1,266 ) (51,520 ) Net operating income $ 50,253 $ 47,077 $ 3,172 $ 100,502 Real estate-related depreciation and amortization $ 33,046 $ 18,771 $ 1,844 $ 53,661 We consider net operating income to be an appropriate supplemental performance measure and believe net operating income provides useful information to our investors regarding our financial condition and results of operations because net operating income reflects the operating performance of our properties and excludes certain items that are not considered to be controllable in connection with the management of the properties, such as real estate-related depreciation and amortization, general and administrative expenses, advisory fees, acquisition expenses, impairment charges, interest expense, gains on sale of properties, other income and expense, gains and losses on the extinguishment of debt and noncontrolling interests. However, net operating income should not be viewed as an alternative measure of our financial performance since it excludes such items, which could materially impact our results of operations. Further, our net operating income may not be comparable to that of other real estate companies, as they may use different methodologies for calculating net operating income. Therefore, we believe net income, as defined by GAAP, to be the most appropriate measure to evaluate our overall financial performance. The following table is a reconciliation of our reported net income (loss) attributable to common stockholders to our net operating income for the three and nine months ended September 30, 2018 and 2017 : For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Net (loss) income attributable to common stockholders $ (3,465 ) $ (1,960 ) $ (1,985 ) $ 6,506 Debt-related income (170 ) (194 ) (514 ) (654 ) Real estate-related depreciation and amortization 14,961 16,927 43,202 53,661 General and administrative expenses 2,076 2,760 6,888 7,034 Advisory fees, related party 3,877 3,274 11,132 10,215 Impairment of real estate property 6,600 — 13,400 1,116 Interest expense 12,166 11,346 35,704 31,193 Gain on sale of real property (1,398 ) (670 ) (13,832 ) (11,022 ) Other (income) expense (42 ) 664 272 862 Net (loss) income attributable to noncontrolling interests (292 ) (185 ) (161 ) 1,591 Net operating income $ 34,313 $ 31,962 $ 94,106 $ 100,502 |