•Net investment income decreased in 2015 versus 2014, due to lower investment yields from the continued low interest rate environment and unfavorable foreign currency effects partially offset by higher average invested assets. In 2014, net investment income was flat compared with 2013, reflecting higher average investment assets offset by lower yields.
We maintain a share repurchase program, authorized by our Board of Directors. Under this program, we may repurchase shares from time to time, depending on market conditions and alternate uses of capital. We may suspend activity under our share repurchase program from time to time and may also remove such suspensions, generally without public announcement. We may also repurchase shares at times by using a Rule 10b5-1 trading plan when we otherwise might be precluded from doing so under insider trading laws or because of self-imposed trading block-out periods.
The above table also does not contain $31 million of liabilities for uncertain tax positions because we cannot reasonably estimate the timing of their resolution with the respective taxing authorities. See Note 19 to the Consolidated Financial Statements for the year ended December 31, 2015 for further information.
Medical costs payable is higher as of December 31, 2015 compared with 2014, primarily due to growth in the stop loss book of business and the Government segment. See Note 5 to the Consolidated Financial Statements for additional information. Medical costs payable increased in 2014 compared with 2013, primarily driven by growth in the individual and stop loss books of business.
• has medical claims that are administered by us. Our medical customer base as of December 31, 2015 was higher than 2014, driven by strong overall retention and sales in our targeted market segments, as well as the acquisition of QualCare Alliance Networks, Inc. on February 28, 2015.
The expense ratio (excluding acquisition costs) increased in both 2015 and 2014 compared with each prior year reflecting strategic business investments partially offset by operating efficiencies.
Future policy benefits represent the present value of estimated future obligations under long-term life and supplemental health insurance policies and annuity products currently in force. These obligations are estimated using actuarial methods and consist primarily of reserves for annuity contracts, life insurance benefits, guaranteed minimum death benefit ("GMDB") contracts (see Note 7 for additional information) and certain health, life and accident insurance products of our Global Supplemental Benefits segment.
Assumptions for pension and other postretirement benefit plans. Management determined the present value of the projected benefit obligation and the accumulated other postretirement benefit obligation and related benefit costs based on the following weighted average assumptions as of and for the years ended December 31:
(1) Fixed maturities included $483 million of net cumulative appreciation required to adjust future policy benefits for the run-off settlement annuity business including $30 million of appreciation for securities classified in Level 3. See Note 11 for additional information.
At December 31, 2015, scheduled commercial mortgage loan maturities were as follows (in millions): $205 in 2016, $143 in 2017, $177 in 2018, $275 in 2019 and $1,064 thereafter. Actual maturities could differ from contractual maturities for several reasons: borrowers may have the right to prepay obligations with or without prepayment penalties; the maturity date may be extended; and loans may be refinanced.
Credit quality. The Company regularly evaluates and monitors credit risk, beginning with the initial underwriting of a mortgage loan and continuing throughout the investment holding period. Mortgage origination professionals employ an internal credit quality rating system designed to evaluate the relative risk of the transaction at origination that is then updated each year as part of the annual portfolio loan review. The Company evaluates and monitors credit quality on an ongoing basis, classifying each loan as a loan in good standing, potential problem loan or problem loan.
(1)These write-downs pertain to other-than-temporary declines in fair values due to increases in market yields (widening of credit spreads), particularly within the energy sector, for certain below investment grade fixed maturities with an increased probability of sales activity prior to recovery of amortized cost basis.
being redeemed, discounted at a rate equal to the 10-year Treasury Rate plus a fixed spread of 50 basis points. The Company paid $329 million including accrued interest and expenses, resulting in a pre-tax loss on early debt extinguishment of $79 million ($51 million after-tax) that was recognized in the second quarter of 2015.
The fair value of vested restricted stock was: $92 million in 2015, $85 million in 2014 and $94 million in 2013.
• run-off reinsurance business that is predominantly comprised of GMDB and GMIB business effectively exited through reinsurance with Berkshire in 2013;
The Company had indemnification obligations as of December 31, 2015 in connection with acquisition, disposition and reinsurance transactions. These indemnification obligations are triggered by the breach of representations or covenants provided by the Company, such as representations for the presentation of financial statements, actuarial models, the filing of tax returns, compliance with law or the identification of outstanding litigation. These obligations are typically subject to various time limitations, defined by the contract or by
The Company operates in a regulatory environment that may require the Company to participate in assessments under state insurance guaranty association laws. The Company's exposure to assessments for certain obligations of insolvent insurance companies to policyholders and claimants is based on its share of business written in the relevant jurisdictions. For the year ended December 31, 2015 and 2014, charges related to guaranty fund assessments were immaterial to the Company's results of operations.