<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
COMPANY'S CONSOLIDATED STATEMENTS OF INCOME AND CONSOLIDATED BALANCE SHEETS AND
IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<RESTATED> 
<MULTIPLIER> 1,000,000
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   6-MOS                   9-MOS                   9-MOS                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1996             DEC-31-1995
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1996             JAN-01-1995
<PERIOD-END>                               JUN-30-1997             SEP-30-1997             SEP-30-1996             DEC-31-1995
<CASH>                                             297                     347                     211                     338
<SECURITIES>                                        28                      24                      56                      71
<RECEIVABLES>                                      404                     416                     236                     242
<ALLOWANCES>                                        39                      35                      29                      22
<INVENTORY>                                         81                      76                      56                      14
<CURRENT-ASSETS>                                   927                   1,018                     610                     717
<PP&E>                                           6,091                   6,167                   2,646                   2,490
<DEPRECIATION>                                   1,139                   1,164                     889                     794
<TOTAL-ASSETS>                                   7,676                   7,895                   3,019                   3,060
<CURRENT-LIABILITIES>                              862                     902                     355                     535
<BONDS>                                          2,745                   2,770                   1,087                   1,070
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                         15                      15                       0                       0
<COMMON>                                           627                     628                     494                     128
<OTHER-SE>                                       2,712                   2,801                     898                   1,126
<TOTAL-LIABILITY-AND-EQUITY>                     7,676                   7,895                   3,019                   3,060
<SALES>                                          2,663                   3,977                   1,353                   1,649
<TOTAL-REVENUES>                                 2,663                   3,977                   1,353                   1,649
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                    2,242                   3,349                   1,005                   1,243
<OTHER-EXPENSES>                                    35                      49                      37                      32
<LOSS-PROVISION>                                    26                      21                      18                      21
<INTEREST-EXPENSE>                                  88                     110                      39                      75
<INCOME-PRETAX>                                    286                     448                     254                     280
<INCOME-TAX>                                       118                     184                     100                     103
<INCOME-CONTINUING>                                161                     255                     150                     173
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                       161                     255                     150                     173
<EPS-PRIMARY>                                      .62                     .98                     .77                     .90
<EPS-DILUTED>                                      .60                     .95                     .76                     .89
        

</TABLE>