(18) Common Stockholders’ Equity (19) Fair Value of Financial Instruments 98 The estimated fair values of the Company’s fixed maturity securities, equity securities available for sale and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 12 above. The fair value of loans receivable is estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments as of December 31, 2018 and 2017: The amount of dividends paid is dependent upon factors such as the receipt of dividends from our subsidiaries, our results of operations, cash flow, financial condition and business needs, the capital and surplus requirements of our subsidiaries, and applicable insurance regulations that limit the amount of dividends that may be paid by our regulated insurance subsidiaries. Treasury shares have been excluded from average outstanding shares from the date of acquisition. The weighted average number of basic shares outstanding includes the impact of 4,926,521 common shares held in a grantor trust. The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since shares deliverable under vested RSUs were already included in diluted shares outstanding. The difference in calculating basic and diluted net income per share is attributable entirely to the dilutive effect of stock-based compensation plans. Changes in shares of common stock outstanding, net of treasury shares, are presented below. Shares of common stock issued and outstanding do not include shares related to unissued restricted stock units (including shares held in the grantor trust). The weighted average number of shares used in the computation of net income per share was as follows: 2018 2017 2016 Basic 126,698,927 124,843,240 122,650,997 Diluted 128,263,558 129,017,613 128,552,838 2018 2017 2016 Balance, beginning of year 121,514,852 121,193,599 123,307,837 Shares issued 838,508 1,052,256 281,654 Shares repurchased (357,600 ) (731,003 ) (2,395,892) Balance, end of year 121,995,760 121,514,852 121,193,599 2018 2017 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,606,812 $ 13,619,620 $ 13,551,250 $ 13,566,976 Equity securities 279,006 279,006 576,647 576,647 Arbitrage trading account 452,548 452,548 617,649 617,649 Loans receivable 94,813 97,073 79,684 82,047 Cash and cash equivalents 817,602 817,602 950,471 950,471 Trading accounts receivable from brokers and clearing organizations 347,228 347,228 189,280 189,280 Liabilities: Due to broker 20,144 20,144 15,920 15,920 Trading account securities sold but not yet purchased 38,120 38,120 64,358 64,358 Subordinated debentures 907,491 840,002 728,218 769,060 Senior notes and other debt 1,882,028 1,968,996 1,769,052 1,945,313