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Income Taxes - Components of Aon's deferred tax assets and liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Deferred tax assets: |  |
Net operating loss, capital loss, interest, and tax credit carryforwards | $ 581 | $ 653
Lease liabilities | 207 | 248
Employee benefit plans | 160 | 312
Other accrued expenses | 132 | 103
Accrued interest | 97 | 0
Federal and state benefit of interest from uncertain tax positions | 45 | 37
Deferred revenue | 36 | 36
Investment basis differences | 25 | 28
Lease and service guarantees | 1 | 2
Other | 25 | 17
Total | 1,309 | 1,436
Valuation allowance on deferred tax assets | (230) | (205)
Total | 1,079 | 1,231
Deferred tax liabilities: |  |
Intangibles and property, plant and equipment | (243) | (291)
Lease right-of-use asset | (173) | (211)
Deferred costs | (159) | (141)
Unremitted earnings | (58) | (37)
Other accrued expenses | (27) | (22)
Unrealized foreign exchange gains | (22) | (26)
Other | (32) | (41)
Total | (714) | (769)
Net deferred tax asset | $ 365 | 462
Federal and state benefit of interest from uncertain tax positions |  | $ 37

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- Definition The sum of the tax effects as of the balance sheet date of the amount of (1) excess of tax deductions over gross income in a year which cannot be used on the tax returns in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset, and capital losses that cannot be utilized on the tax return during a period that have been carried forward to reduce taxable income or taxes payable in a future year and (2) future tax deductions arising from all unused tax credit carryforwards which have been reduced by a valuation allowance. + References No definition available. + Details
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