Fair Value Measurements (Narrative) (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value assets, Level 1 to Level 2 transfers amount	$ 0	$ 0	$ 0
Fair value assets, Level 2 to Level 1 transfers amount	0	0	0
Fair Value Assets Level 1 To Level 3 Transfers Amount	0	0	0
Fair Value Assets Level 3 To Level 1 Transfers Amount	0	0	0
Fair Value Assets Level 2 To Level 3 Transfers Amount	0	0	0
Fair Value Assets Level 3 To Level 2 Transfers Amount	0	0	$ 0
Goodwill
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Recognized impairment losses	34,200,000	34,200,000
Property Plant And Equipment
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Recognized impairment losses	17,600,000	17,600,000
Other Intangible Assets
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Recognized impairment losses	$ 3,200,000	$ 3,200,000