Income Taxes	3 Months Ended
Mar. 31, 2019
Income Taxes [Abstract]
Income Taxes	Note 22—Income Taxes Our effective tax rate for the first quarter of 2019 was 31 percent compared with 49 percent for the first quarter of 2018. The effective tax rate for first quarter 2019 is lower than the effective tax rate for 2018 primarily due to higher before-tax income in lower tax jurisdictions for 2019 as well as a reduction of our U.S. valuation allowance for the first quarter of 2019. During the first quarter of 2019, our U.S. valuation allowance decreased by $103 million compared to an increase of $57 million for the first quarter of 2018. The change to our U.S. valuation allowance for both periods relates primarily to the fair value measurement of our Cenovus Energy common shares.

Income Taxes

3 Months Ended

Mar. 31, 2019

Note 22—Income Taxes

Our effective tax rate for the first quarter of 2019 was 31 percent compared with 49 percent for the first quarter of 2018. The effective tax rate for first quarter 2019 is lower than the effective tax rate for 2018 primarily due to higher before-tax income in lower tax jurisdictions for 2019 as well as a reduction of our U.S. valuation allowance for the first quarter of 2019.

During the first quarter of 2019, our U.S. valuation allowance decreased by $103 million compared to an increase of $57 million for the first quarter of 2018. The change to our U.S. valuation allowance for both periods relates primarily to the fair value measurement of our Cenovus Energy common shares.