<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED>
<MULTIPLIER> 1,000,000

<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   3-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             APR-01-1997             JUL-01-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                             971                     802                   1,072
<SECURITIES>                                       290                     231                     195
<RECEIVABLES>                                      694                     771                     770
<ALLOWANCES>                                        22                      23                      23
<INVENTORY>                                        281                     323                     346
<CURRENT-ASSETS>                                 2,552                   2,428                   2,679
<PP&E>                                           6,272                   6,423                   6,622
<DEPRECIATION>                                   1,723                   1,790                   1,852
<TOTAL-ASSETS>                                   8,978                   9,039                   9,356
<CURRENT-LIABILITIES>                            3,217                   3,156                   3,305
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                              598                       1                     324
<PREFERRED>                                          0                     589                       0
<COMMON>                                             1                       0                     850
<OTHER-SE>                                         165                     309                   (476)
<TOTAL-LIABILITY-AND-EQUITY>                     8,978                   9,039                   9,356
<SALES>                                          2,376                   2,558                   2,801
<TOTAL-REVENUES>                                 2,376                   2,558                   2,801
<CGS>                                                0                       0                       0
<TOTAL-COSTS>                                    2,241                   2,267                   2,298
<OTHER-EXPENSES>                                    30                      69                      31
<LOSS-PROVISION>                                     4                       2                       2
<INTEREST-EXPENSE>                                  57                      59                      59
<INCOME-PRETAX>                                    105                     222                     473
<INCOME-TAX>                                        40                      86                     183
<INCOME-CONTINUING>                                 65                     136                     290
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                        65                     136                     290
<EPS-PRIMARY>                                     0.59                    1.29                    2.80
<EPS-DILUTED>                                     0.53                    1.16                    2.53


</TABLE>