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Stock-based Compensation Plans - Valuation Assumptions for Grant Date Fair Value of TSR - Performance Awards (Detail) - Performance Based TSR - PSUs - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 2.44% 2.42% 1.49%
Expected annual volatility 46.00% 48.00% 44.00%
Grant date fair value per unit [1] $ 11.34 $ 18.51 $ 26.26
[1] These amounts reflect the number of performance units granted. The actual payout of shares may be between zero and 150% (for TSR-PSUs granted in 2017) and may be between zero and 200% (for TSR-PSUs granted in 2018 and 2019) of the performance units granted depending on the total shareholder return ranking compared to our peer companies at the vesting date.