Millions of Dollars | ||||||
2013 | 2012 | |||||
Balance at January 1 | $ | 314 | 378 | |||
Accretion of discount | 11 | 13 | ||||
New obligations | 3 | 3 | ||||
Changes in estimates of existing obligations | 12 | (14 | ) | |||
Spending on existing obligations | (13 | ) | (16 | ) | ||
Property dispositions | (20 | ) | (53 | ) | ||
Foreign currency translation | 2 | 3 | ||||
Balance at December 31 | $ | 309 | 314 | |||