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Income Taxes - Reconciliation of Provision for Income Taxes with Federal Statutory Income Tax Rate (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Income Tax Disclosure [Abstract] |  |  |
Federal statutory rate | $ 204.8 | $ 182.9 | $ 131.5
State income taxes - net of federal benefit | 30.7 | 22.2 | 4.4
Differences related to non U.S. operations | (8.7) | (2.5) | (10.1)
Alternative energy and other tax credits | (199.0) | (154.3) | (196.1)
Other permanent differences | (3.5) | (15.7) | (7.6)
Stock-based compensation | (40.0) | (31.4) | (16.2)
Changes in unrecognized tax benefits | 0.8 |  | 0.8
Change in valuation allowance | 26.4 | 6.5 | 7.5
Change in U.S. and U.K. tax rates | 8.6 | 5.5 | (3.7)
Other |  | (0.4) | (0.2)
Total provision (benefit) for income taxes | $ 20.1 | $ 12.8 | $ (89.7)
Federal statutory rate, % of Pretax Earnings | 21.00% | 21.00% | 21.00%
State income taxes-net of Federal benefit, % of Pretax Earnings | 3.20% | 2.60% | 0.70%
Differences related to non U.S. operations, % of Pretax Earnings | (0.90%) | (0.30%) | (1.60%)
Alternative energy and other tax credits, % of Pretax Earnings | (20.40%) | (17.70%) | (31.30%)
Other permanent differences, % of Pretax Earnings | (0.40%) | (1.80%) | (1.20%)
Stock-based compensation | (4.10%) | (3.60%) | (2.60%)
Changes in unrecognized tax benefits, % of Pretax Earnings | 0.10% |  | 0.10%
Change in valuation allowance, % of Pretax Earnings | 2.70% | 0.70% | 1.20%
Change in U.S. and U.K. tax rates | 0.90% | 0.60% | (0.60%)
Total provision (benefit) for income taxes, % of Pretax Earnings | 2.10% | 1.50% | (14.30%)

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