Operating lease rental expense for the years ended December 31 was: | |||||||
Millions of Dollars | |||||||
2013 | 2012 | 2011 | |||||
Total rentals* | $ | 317 | 282 | 304 | |||
Less: sublease rentals | (12) | (15) | (14) | ||||
$ | 305 | 267 | 290 | ||||
*Includes $3 million and $29 million of contingent rentals in 2012 and 2011, respectively. Contingent rentals were primarily related to drilling | |||||||
equipment and based on usage. |