| | Post-Employment benefits | | | Long-term Benefits | | ||||||||||||||||||
| | December 31, 2017 | | | December 31, 2016 | | | December 31, 2015 | | | December 31, 2017 | | | December 31, 2016 | | | December 31, 2015 | | ||||||
Balance at the beginning of the year | | Ps. | 509,022 | | | Ps. | 436,696 | | | Ps. | 442,258 | | | Ps. | 191,112 | | | Ps. | 206,971 | | | Ps. | 188,522 | |
Service costs | | | 4,425 | | | | 3,006 | | | | 2,158 | | | | 18,201 | | | | 19,243 | | | | 16,745 | |
Interests cost | | | 51,027 | | | | 69,348 | | | | 31,338 | | | | 8,928 | | | | (20,274 | ) | | | 11,975 | |
Gain on settlements | | | 252 | | | | - | | | | - | | | | (112 | ) | | | - | | | | - | |
Past Service Costs | | | - | | | | - | | | | 2,712 | | | | - | | | | - | | | | 2,711 | |
| | | 564,726 | | | | 509,050 | | | | 478,466 | | | | 218,129 | | | | 205,940 | | | | 219,953 | |
| | | | | | | | | | | | | | | | | | | | | | | | |
Changes in actuarial assumptions from changes in demographic assumptions. | | | (8,863 | ) | | | (1,232 | ) | | | 7,171 | | | | (1,432 | ) | | | (6,456 | ) | | | (2,162 | ) |
Changes in actuarial assumptions from changes in financial assumptions. | | | 109,095 | | | | 42,460 | | | | (1,009 | ) | | | 43,870 | | | | 18,845 | | | | 7,515 | |
| | | 100,232 | | | | 41,228 | | | | 6,162 | | | | 42,438 | | | | 12,389 | | | | 5,353 | |
| | | | | | | | | | | | | | | | | | | | | | | | |
Exchange differences | | | (982 | ) | | | 6,083 | | | | (27 | ) | | | - | | | | - | | | | 8,236 | |
Payments to employees | | | (59,866 | ) | | | (47,337 | ) | | | (47,905 | ) | | | (30,797 | ) | | | (27,217 | ) | | | (26,571 | ) |
Balance at the end of the year | | Ps. | 604,110 | | | Ps. | 509,022 | | | Ps. | 436,696 | | | Ps. | 229,770 | | | Ps. | 191,112 | | | Ps. | 206,971 | |