Income taxes - Tax credit carryforward (Details) $ in Millions	Dec. 31, 2020 USD ($)
Income taxes
Income tax receivables through acquisition	$ 2
Federal
Income taxes
Operating losses carried forward	791
Net operating losses carried forward subject to expiration	512
Net operating losses carried forward not subject to expiration	279
Tax credits carried forward research and development	77
Foreign
Income taxes
Operating losses carried forward	16
Net operating losses carried forward not subject to expiration	16
U.S.
Income taxes
Tax credits carried forward research and development	5
State
Income taxes
Operating losses carried forward	822
Net operating losses carried forward subject to expiration	756
Net operating losses carried forward not subject to expiration	66
Tax credits carried forward research and development	$ 11

The amount of income tax receivables through acquisition.

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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws, not subject to expiration.

+ References

No definition available.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws, subject to expiration.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

+ References

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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