Three Months Ended March 31, | Year Ended December 31, | ||||||||||||||||||
2018 | 2017 | 2016 | 2015 | 2014 | 2013 | ||||||||||||||
Earnings: | |||||||||||||||||||
Income before income taxes | $ | 1,661 | $ | 7,137 | $ | 5,121 | $ | 7,337 | $ | 4,641 | $ | 6,666 | |||||||
Add: Interest expense | 153 | 453 | 381 | 341 | 353 | 380 | |||||||||||||
Add: Interest factor in rental expense | 68 | 268 | 229 | 223 | 225 | 192 | |||||||||||||
Total earnings | $ | 1,882 | $ | 7,858 | $ | 5,731 | $ | 7,901 | $ | 5,219 | $ | 7,238 | |||||||
Fixed charges: | |||||||||||||||||||
Interest expense | $ | 153 | $ | 453 | 381 | $ | 341 | $ | 353 | $ | 380 | ||||||||
Interest capitalized | 17 | 49 | 14 | 13 | 11 | 14 | |||||||||||||
Interest factor in rental expense | 68 | 268 | 229 | 223 | 225 | 192 | |||||||||||||
Total fixed charges | $ | 238 | $ | 770 | $ | 624 | $ | 577 | $ | 589 | $ | 586 | |||||||
Ratio of earnings to fixed charges | 7.9 | 10.2 | 9.2 | 13.7 | 8.9 | 12.4 | |||||||||||||