Earnings Per Share - Number of Shares Underlying Stock Options Excluded from Computation of Diluted Loss (Detail) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive stock options	0.0		0.3
Average exercise price			$ 42.43
Year(s) of expiration	0	0
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive stock options			0.1
Minimum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Year(s) of expiration			2024
Maximum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Year(s) of expiration			2025