performed on aggregated blocks of existing business to determine if gross revenues less expenses are sufficient to cover the existing DAC balance.
Premium income decreased by $25 million, or 5%, to $440 million, in 2017. The decrease was primarily related to lower net premiums collected on group health and disability policies.
Separate account liabilities have been excluded from the table above. Separate account obligations are legally insulated from general account assets. Separate account liabilities represent funds maintained by the Company to meet the specific investment objectives of the contract holders who bear the related investment risk. It is generally expected that the separate account liabilities will be fully funded by the separate account assets.
Separate account assets and liabilities - various index data and news sources, amortized cost (which approximates fair value), trading activity, swap curves, credit spreads, recovery rates, restructuring, net present value of cash flows, and quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly.
Life insurance premiums are recognized when due. Annuity contract premiums with life contingencies are recognized as received. Revenues for annuity and other contracts without significant life contingencies consist of contract charges for the cost of insurance, and contract administration and surrender fees that have been assessed against the contract account balance during the period and are recognized when earned in fee income. Fees from assets under management, assets under administration, shareholder servicing, mortality and expense risk charges, administration and recordkeeping services, and investment advisory services are recognized when earned in fee income.
Total unrealized losses greater than twelve months decreased by $40,149 from December 31, 2016, to December 31, 2017. Corporate debt securities account for 80%, or $90,809, of the unrealized losses and OTTI greater than twelve months at December 31, 2017. Non-investment grade corporate debt securities account for $6,244 of the unrealized losses and OTTI greater than twelve months. Management does not have the intent to sell these assets; therefore, an OTTI was not recognized in earnings.
(B) Represents realized gains (losses) on closed positions recorded in realized investment gains (losses), net.
The Company calculates additional liabilities for GMDB and GLWB. The following assumptions and methodology were used to determine GMDB additional reserves at December 31, 2017, and 2016 .
asset class using historical data and other qualitative considerations to adjust for projected economic forecasts are used to set the expected rate of return for the entire portfolio.
The Chief Operating Decision Maker (“CODM”) of the Company is also the Chief Executive Officer (“CEO”) of the Company and Lifeco U.S. The CODM reviews the financial information for the purposes of assessing performance and allocating resources based upon the results of Lifeco U.S. and other U.S. affiliates prepared in accordance with International Financial Reporting Standards. The CODM, in his capacity as CEO of the Company, reviews the Company’s financial information only in connection with the quarterly and annual reports that are filed with the Securities and Exchange Commission (“SEC”). Consequently, the Company does not provide its discrete financial information to the CODM to be regularly reviewed to make decisions about resources to be allocated or to assess performance. For purposes of SEC reporting requirements, the Company has chosen to present its financial information in three segments, notwithstanding the above. The three segments are: Individual Markets, Empower Retirement, and Other.