| 
 (€ million)  | 
 Net book value at the be-  | 
 Ad-  | 
 Depre-  | 
 Impair-  | 
 Changes in the scope of conso-  | 
 Cur-  | 
 Re-  | 
 Other changes  | 
 Net book value at the end of the year  | 
 Gross book value at the end of the year  | 
 Provi-  | 
| 
 December 31, 2012  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
| 
 Land  | 
 771  | 
 5  | 
 
  | 
 
  | 
 (109)  | 
 (8)  | 
 (8)  | 
 4  | 
 655  | 
 678  | 
 23  | 
| 
 Buildings  | 
 1,427  | 
 61  | 
 (108)  | 
 (45)  | 
 (316)  | 
 (2)  | 
 (7)  | 
 148  | 
 1,158  | 
 3,150  | 
 1,992  | 
| 
 Plant and machinery  | 
 47,494  | 
 1,546  | 
 (7,012)  | 
 (1,079)  | 
 (9,719)  | 
 (313)  | 
 (304)  | 
 8,283  | 
 38,896  | 
 112,170  | 
 73,274  | 
| 
 Industrial and commercial equipment  | 
 459  | 
 74  | 
 (112)  | 
 (3)  | 
 (62)  | 
 3  | 
 
  | 
 3  | 
 362  | 
 1,660  | 
 1,298  | 
| 
 Other assets  | 
 829  | 
 89  | 
 (103)  | 
 (75)  | 
 (12)  | 
 (7)  | 
 
  | 
 5  | 
 726  | 
 2,239  | 
 1,513  | 
| 
 Tangible assets in progress and advances  | 
 22,598  | 
 9,447  | 
 
  | 
 (407)  | 
 (2,207)  | 
 (187)  | 
 (130)  | 
 (7,445)  | 
 21,669  | 
 23,400  | 
 1,731  | 
| 
 
  | 
 73,578  | 
 11,222  | 
 (7,335)  | 
 (1,609)  | 
 (12,425)  | 
 (514)  | 
 (449)  | 
 998  | 
 63,466  | 
 143,297  | 
 79,831  | 
| 
 December 31, 2013  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
 
  | 
| 
 Land  | 
 655  | 
 10  | 
 
  | 
 (8)  | 
 
  | 
 (19)  | 
 (3)  | 
 9  | 
 644  | 
 670  | 
 26  | 
| 
 Buildings  | 
 1,158  | 
 72  | 
 (115)  | 
 (37)  | 
 18  | 
 (29)  | 
 (7)  | 
 194  | 
 1,254  | 
 3,369  | 
 2,115  | 
| 
 Plant and machinery  | 
 38,896  | 
 3,820  | 
 (6,995)  | 
 (1,847)  | 
 
  | 
 (1,523)  | 
 (145)  | 
 8,263  | 
 40,469  | 
 119,335  | 
 78,866  | 
| 
 Industrial and commercial equipment  | 
 362  | 
 141  | 
 (116)  | 
 (4)  | 
 
  | 
 (17)  | 
 
  | 
 31  | 
 397  | 
 1,758  | 
 1,361  | 
| 
 Other assets  | 
 726  | 
 80  | 
 (110)  | 
 (1)  | 
 1  | 
 (10)  | 
 
  | 
 (315)  | 
 371  | 
 1,908  | 
 1,537  | 
| 
 Tangible assets in progress and advances  | 
 21,669  | 
 6,741  | 
 
  | 
 (219)  | 
 
  | 
 (996)  | 
 
  | 
 (7,824)  | 
 19,371  | 
 21,355  | 
 1,984  | 
| 
 
  | 
 63,466  | 
 10,864  | 
 (7,336)  | 
 (2,116)  | 
 19  | 
 (2,594)  | 
 (155)  | 
 358  | 
 62,506  | 
 148,395  | 
 85,889  |