Income taxes

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income taxes

Income taxesOur estimated annual effective tax rate is about 14%, which does not include discrete tax items. This differs from the 21% U.S. statutory corporate tax rate due to the effect of U.S. tax benefits.Provision for income taxes is based on the following:

	For Three Months Ended
	March 31,
	2022			2021
Taxes calculated using the estimated annual effective tax rate	$	361		$	275
Discrete tax items	(36)			(89)
Provision for income taxes	$	325		$	186
Effective tax rate	13		%	10		%