The Company owns its home office building and the adjacent real estate in Carmel, Indiana. The home office building contains a total of 181,000 square feet of usable space, and the Company currently occupies approximately 74% of this space, with a portion of the remainder being leased to non-affiliated entities on short-term leases expiring through 2023.
Our assets at December 31, 2020 included $47.0 million of investments included within cash and cash equivalents on the consolidated balance sheet that are readily convertible to cash without market penalty and an additional $117.0 million of fixed income investments maturing in less than one year. We believe these liquid investments, plus the expected cash flow from premium collections, are sufficient to provide for projected claim payments and operating cost demands. In the event competitive conditions produce inadequate premium rates and we choose to further restrict volume or our premiums are further restricted due to market conditions, including related to the impact of COVID-19, we believe the liquidity of our investment portfolio would permit us to continue to pay claims as settlements are reached without requiring the disposal of investments at a loss, regardless of interest rates in effect at the time.
The ratio of consolidated other operating expenses, less commissions and other income, to net premiums earned, or our expense ratio, and the ratio of losses and loss expenses incurred, plus other operating expenses, less commissions and other income, to net premiums earned, or our combined ratio, are measures of our profitability that we believe increase the period-to-period comparability of our operational results. For the year ended December 31, 2020, we also excluded the corporate charges and CECL allowance adjustment, and for the year ended December 31, 2018, we also excluded the goodwill impairment charge, discussed above from other operating expenses when calculating our expense ratio and our combined ratio, as these ratios are intended to depict our underlying business performance and ongoing operating trends. We believe the exclusion of these charges and the CECL allowance adjustment improves the comparability of our expense and combined ratios with our ratios in prior years. Our management uses these ratios to evaluate performance, allocate resources and forecast future operating periods. While expense ratios and combined ratios are widely used within our industry, our use of such ratios may not be directly comparable to similarly titled measures reported by other companies.
The table below sets forth the amounts of the Company's contractual obligations at December 31, 2020.
The Company reports investment income due and accrued separately from available-for-sale fixed income securities and has elected not to measure an allowance for credit losses for investment income due and accrued. Investment income due and accrued is written off through net realized gains (losses) on investments, excluding impairment losses at the time the issuer defaults or is expected to default on payments.
The Insurance Subsidiaries cede portions of their gross premiums written to certain other insurers under excess of loss and quota share treaties and by facultative placements. Some reinsurance contracts provide that a loss be shared among the Company and its reinsurers on a predetermined pro-rata basis ("quota share"), while other contracts provide that the Company keep a fixed amount of the loss, similar to a deductible, with reinsurers taking all losses above this fixed amount ("excess of loss"). Reinsurance treaties with other companies permit the recovery of a portion of related direct losses. Management determines the amount of net exposure it is willing to accept generally on a product-line basis. Certain treaties covering commercial automobile risks include annual deductibles which must be exceeded before the Company can recover under the terms of the treaty. The Company retains a higher percentage of the direct premium in consideration of these deductible provisions. The Company remains liable to the extent the reinsuring companies are unable to meet their obligations under reinsurance contracts.
Details of changes in net unrealized gains (losses) on investments for the years ended December 31, 2020, 2019 and 2018 are as follows:
The Company maintains a defined contribution 401(k) Employee Savings and Profit Sharing Plan (the "Plan") which covers nearly all employees. The Company's contributions are based on a set percentage and the contributions to the Plan for 2020, 2019 and 2018 were $3,274, $3,213 and $3,486, respectively.
The Company did not have any Level 3 assets at December 31, 2020 or 2019. Level 3 assets, when present, are valued using various unobservable inputs including extrapolated data, proprietary models and indicative quotes.