Income Taxes	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	18. Income Taxes On December 22, 2017, The Tax Cuts and Jobs Act (the “2017 Tax Act”) was enacted. The 2017 Tax Act significantly revises the U.S. tax code, including, but not limited to, (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent, (2) requiring companies to pay a one-time tax on certain unrepatriated earnings of foreign subsidiaries, (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries, (4) creating new taxes on certain earnings of controlled foreign corporations, and (5) creating a new limitation on deductible net interest expense. BlackRock’s results in 2017 included a $1.2 billion net tax benefit related to the 2017 Tax Act. The Company has not made any additional measurement-period adjustments during the three months ended March 31, 2018. The Company may record adjustments to the provisional amounts during the measurement period as additional guidance from the U.S. Department of the Treasury is provided, as changes in the Company’s assumptions occur, and as further information and interpretations become available. For further information on the 2017 Tax Act, see Note 21, Income Taxes, in the consolidated financial statements included in the 2017 Form 10-K. The first quarter 2018 income tax expense reflected a reduced tax rate associated with the 2017 Tax Act and included a $56 million discrete tax benefit related to stock-based compensation awards that vested in the first quarter of 2018. The first quarter 2017 income tax expense included an $81 million discrete tax benefit related to stock-based compensation awards that vested in the first quarter of 2017.

18. Income Taxes

On December 22, 2017, The Tax Cuts and Jobs Act (the “2017 Tax Act”) was enacted. The 2017 Tax Act significantly revises the U.S. tax code, including, but not limited to, (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent, (2) requiring companies to pay a one-time tax on certain unrepatriated earnings of foreign subsidiaries, (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries, (4) creating new taxes on certain earnings of controlled foreign corporations, and (5) creating a new limitation on deductible net interest expense. BlackRock’s results in 2017 included a $1.2 billion net tax benefit related to the 2017 Tax Act. The Company has not made any additional measurement-period adjustments during the three months ended March 31, 2018. The Company may record adjustments to the provisional amounts during the measurement period as additional guidance from the U.S. Department of the Treasury is provided, as changes in the Company’s assumptions occur, and as further information and interpretations become available. For further information on the 2017 Tax Act, see Note 21, Income Taxes, in the consolidated financial statements included in the 2017 Form 10-K.

The first quarter 2018 income tax expense reflected a reduced tax rate associated with the 2017 Tax Act and included a $56 million discrete tax benefit related to stock-based compensation awards that vested in the first quarter of 2018.

The first quarter 2017 income tax expense included an $81 million discrete tax benefit related to stock-based compensation awards that vested in the first quarter of 2017.