Income Taxes - Tax Effected Operating Loss, Capital Loss, and Tax Credit Carryovers (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Income tax
Net UTB impacting the effective tax rate	$ 1,140		$ 1,140		$ 1,178
Deferred tax assets valuation allowance	$ 150		$ 150		$ 158
Effective tax rate (as a percent)	21.00%	21.80%	19.20%	20.10%
Increase (decrease) in effective income tax rate from prior reporting period to current reporting period (as a percent)	(0.80%)		(0.90%)
Decrease in unrecognized tax benefits due to resolution of a lawsuit			$ 52

Decrease in unrecognized tax benefit due to the tax treatment of an agreement reached on a lawsuit.

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- Definition

The difference between the effective income tax rate from the prior reporting period to the current reporting period (as a percent).

+ References

No definition available.

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- References

No definition available.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(2))
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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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-Publisher FASB
-Name Accounting Standards Codification
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