Stockholders' Deficit - Summarizes the Company's Pre-tax Share-based Incentive Compensation Expense and Income Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	$ 34.4	$ 29.9	$ 48.5
Associated tax benefits recognized	5.8	4.9	11.8
2019 Three-year PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	4.3	0.0	0.0
2018 Three-year PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.2	2.7	0.0
2017 Three-year PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.0	3.7	9.8
2017 COO and Chief Executive Officer-Designate 2017 New Hire Equity Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.2	0.2	0.1
2016 Three-year PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.0	(3.0)	2.0
2016 President & CEO Inducement Award
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.0	0.0	0.5
2015 Three-year PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.0	0.0	(0.8)
2014 Special PSU Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	0.0	0.0	3.2
Share-based compensation expense settled in cash			1.0
SLO Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	3.2	1.6	1.1
Other long-term share-based incentive compensation programs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based incentive compensation expense	$ 26.5	$ 24.7	$ 32.6

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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