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Stock-Based Compensation - Pre-Tax Effect Within Consolidated Statements of Operations of Recording Stock-Based Compensation (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense | $ 29.5 | $ 49.2 | $ 27.3
Cost of Revenues [Member] |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense | 4.2 | 2.8 | 3.5
Research and Development [Member] |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense | 4.0 | 3.8 | 2.8
Selling, General and Administrative [Member] |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense | 20.4 | 20.5 | $ 21.0
Acquisition and Integration Cost [Member] |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense | $ 0.9 | 21.7 |
Restructuring Related Expense [Member] |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |
Stock-based compensation expense |  | $ 0.4 |

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