<TABLE> <S> <C>

<PAGE>

<ARTICLE> 7
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997
<PERIOD-START>                             APR-01-1997             JAN-01-1997
<PERIOD-END>                               JUN-30-1997             JUN-30-1997
<DEBT-HELD-FOR-SALE>                         1,098,606               1,098,606
<DEBT-CARRYING-VALUE>                                0                       0
<DEBT-MARKET-VALUE>                                  0                       0
<EQUITIES>                                     135,119                 135,119
<MORTGAGE>                                           0                       0
<REAL-ESTATE>                                        0                       0
<TOTAL-INVEST>                               1,233,725               1,233,725
<CASH>                                          56,639                  56,639
<RECOVER-REINSURE>                              38,595                  38,595
<DEFERRED-ACQUISITION>                          86,262                  86,262
<TOTAL-ASSETS>                               2,001,040               2,001,040
<POLICY-LOSSES>                              1,042,855               1,042,855
<UNEARNED-PREMIUMS>                            306,716                 306,716
<POLICY-OTHER>                                       0                       0
<POLICY-HOLDER-FUNDS>                                0                       0
<NOTES-PAYABLE>                                100,000                 100,000
<PREFERRED-MANDATORY>                                0                       0
<PREFERRED>                                          0                       0
<COMMON>                                       150,114                 150,114
<OTHER-SE>                                     272,231                 272,231
<TOTAL-LIABILITY-AND-EQUITY>                 2,001,040               2,001,040
<PREMIUMS>                                      95,921                 174,384
<INVESTMENT-INCOME>                             21,074                  41,063
<INVESTMENT-GAINS>                               1,582                   7,512
<OTHER-INCOME>                                   3,947                   7,359
<BENEFITS>                                      65,005                 116,272
<UNDERWRITING-AMORTIZATION>                     27,121                  49,764
<UNDERWRITING-OTHER>                             3,243                   7,214
<INCOME-PRETAX>                                 20,218                  43,700
<INCOME-TAX>                                     3,714                   9,052
<INCOME-CONTINUING>                             16,504                  34,648
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                    16,504                  34,648
<EPS-PRIMARY>                                     0.64                    1.33
<EPS-DILUTED>                                     0.63                    1.32
<RESERVE-OPEN>                                 823,979                 823,979
<PROVISION-CURRENT>                             63,405                 116,272
<PROVISION-PRIOR>                                1,600                       0
<PAYMENTS-CURRENT>                               1,367                   1,425
<PAYMENTS-PRIOR>                                49,277                 113,461
<RESERVE-CLOSE>                                825,365                 825,365
<CUMULATIVE-DEFICIENCY>                              0                       0
        

</TABLE>