Income tax expense in 2017 was impacted by the enactment of the Tax Cuts and Jobs Act (TCJA) on December 22, 2017, which reduced the corporate income tax rate from 35% to 21%. Income tax expense increased by $10.1 million related to the
Future trends-premium revenue - The Exchange plans to continue its efforts to grow premiums and improve its competitive position in the marketplace. Expanding the size of its agency force through a careful agency selection process and increased market penetration in our existing operating territories will contribute to future growth as existing and new agents build their books of business.
Our available-for-sale equity securities consist of common stock and nonredeemable preferred stock and are carried at fair value on the Statements of Financial Position with all changes in unrealized gains and losses reflected in other comprehensive income. The net unrealized loss on equity securities classified as available-for-sale, net of deferred taxes, was $0.1 million at both December 31, 2017 and December 31, 2016.
recognize lease expense as a component of operating expenses in the Statements of Operations. We are evaluating our lease contracts to determine those that qualify for treatment as leases under the new guidance and the impact to our financial statements and disclosures.
Available-for-sale securities - Fixed maturity, preferred stock, and common stock securities classified as available-for-sale are reported at fair value. Common stock securities classified as available-for-sale represent certain exchange traded funds with underlying holdings of fixed maturity securities. Available-for-sale securities with a remaining maturity of 12 months or less are reported as current assets on the Statements of Financial Position. Unrealized holding gains and losses, net of related tax effects, on available-for-sale securities are recorded directly to shareholders' equity as accumulated other comprehensive
There were no transfers between Level 1 and Level 2 for the years ended December 31, 2017 and 2016.
The economic assumptions that have the most impact on the postretirement benefits expense are the discount rate and the long-term rate of return on plan assets. The discount rate assumption used to determine the benefit obligation for 2017 was based upon a yield curve developed from corporate bond yield information. The same methodology was employed to develop the discount rates used to determine the benefit obligation for 2016 and 2015.
At December 31, 2017, the plan awards for the 2015-2017 performance period were fully vested. Distributions will be made in 2018 once peer group financial information becomes available. The estimated plan award based upon the peer group information as of September 30, 2017 is $8.4 million. At December 31, 2016, the awards for the 2014-2016 performance period were fully vested. Participants had the option of receiving either cash or stock for the 2014-2016 and 2013-2015 awards. The cash award of $4.7 million was paid in June 2017 and the stock award of 46,884 shares with an average share price of $126.21 and a market value of $5.9 million was delivered to plan participants in June 2017. At December 31, 2015, the awards, granted as stock, for the 2013-2015 performance period were fully vested. The cash award of $12.6 million was paid in June 2016 and the stock award of 7,661 shares with an average share price of $96.64 and a market value of $0.7 million was delivered to plan participants in June 2016.
Class A diluted earnings per share was reduced by $0.19 for the fourth quarter and total year as a result of increased income tax expense from enactment of the TCJA of $10.1 million. See Note 3, "Earnings Per Share" and Note 10, "Income Taxes".