Consolidated Statement of Income (Unaudited) - USD ($)
shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Revenues        
Premiums $ 6,067 $ 5,931 $ 12,048 $ 11,819
Net investment income 549 632 1,093 1,224
Fee income 119 115 236 229
Net realized investment gains [1] 19 10 10 20
Other revenues 31 22 84 47
Total revenues 6,785 6,710 13,471 13,339
Claims and expenses        
Claims and claim adjustment expenses 3,762 3,547 7,474 6,978
Amortization of deferred acquisition costs 989 963 1,960 1,926
General and administrative expenses 1,054 1,032 2,049 2,027
Interest expense 93 92 184 184
Total claims and expenses 5,898 5,634 11,667 11,115
Income before income taxes 887 1,076 1,804 2,224
Income tax expense 223 264 449 579
Net income $ 664 $ 812 $ 1,355 $ 1,645
Net income per share        
Basic $ 2.27 $ 2.56 $ 4.60 $ 5.14
Diluted $ 2.24 $ 2.53 $ 4.55 $ 5.08
Weighted average number of common shares outstanding        
Basic 290.1 314.8 292.1 317.7
Diluted 293.6 318.0 295.6 321.2
Cash dividends declared per share $ 0.67 $ 0.61 $ 1.28 $ 1.16
[1] Total other-than-temporary impairment (OTTI) losses were $(4) million and $(8) million for the three months ended June 30, 2016 and 2015, respectively, and $(32) million and $(12) million for the six months ended June 30, 2016 and 2015, respectively. Of total OTTI, credit losses of $(4) million and $(6) million for the three months ended June 30, 2016 and 2015, respectively, and $(22) million and $(9) million for the six months ended June 30, 2016 and 2015, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $0 million and $(2) million for the three months ended June 30, 2016 and 2015, respectively, and $(10) million and $(3) million for the six months ended June 30, 2016 and 2015, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.