Profit Sharing, Retirement Savings Plans and Defined Benefit Pension Plans - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Provisions charged from operations for the profit sharing plan and retirement savings plans	$ 39.3	$ 36.3	$ 39.9
Contribution of common stock to profit sharing plan (in shares)	487,108	538,524	502,519
Defined benefit pension plan corridor rate	10.00%
Plan assets	$ 762.0	$ 668.7
Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 146.9	147.1
Bulk Annuity Contract
Defined Benefit Plan Disclosure [Line Items]
Plan assets		119.5
Minimum | Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	65.00%
Maximum | Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	75.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 762.0	$ 668.7	$ 776.2
Expected contribution	20.0
Expected benefits paid	$ 3.6