Income Taxes - Income from continuing operations before income tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (loss) before income taxes:
Income before income taxes	$ 2,465	$ 1,871	$ 1,246
Current:
Total current tax expense	439	333	371
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	9	(36)	(225)
Total income tax expense	448	297	146
Ireland
Income (loss) before income taxes:
Income before income taxes	(86)	200	208
Current:
Total current tax expense	2	1	2
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	(1)	(1)	(1)
U.K.
Income (loss) before income taxes:
Income before income taxes	634	228	(240)
Current:
Total current tax expense	30	20	21
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	39	35	19
U.S. federal
Income (loss) before income taxes:
Income before income taxes	(29)	(219)	(601)
Current:
Total current tax expense	126	22	101
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	(72)	(20)	(165)
U.S. state and local
Current:
Total current tax expense	22	41	35
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	(4)	(27)	(56)
Other
Income (loss) before income taxes:
Income before income taxes	1,946	1,662	1,879
Current:
Total current tax expense	259	249	212
Deferred tax expense (benefit):
Total deferred tax expense (benefit)	$ 47	$ (23)	$ (22)