Income Taxes - Reconciliations of Gross Unrecognized Tax Benefits (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Amount of tax benefits that, if recognized, would impact the effective tax rate	$ 47,000,000.0
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	51,400,000	$ 13,800,000	$ 46,300,000
Gross increases for tax positions in prior periods	400,000	44,000,000.0	4,700,000
Gross decreases for tax positions in prior periods	(800,000)	(4,400,000)	(3,400,000)
Gross increases based on tax positions related to the current year	400,000	900,000	700,000
Gross decreases related to settlements with taxing authorities	(2,900,000)	(1,800,000)	(33,600,000)
Reductions due to statute expiration	(1,100,000)	(1,100,000)	(900,000)
Ending balance	47,400,000	$ 51,400,000	$ 13,800,000
Minimum
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	0
Maximum
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 4,300,000