Pension and Savings Plans Textuals (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2017 USD ($) years plan	Dec. 31, 2017 USD ($)	Dec. 31, 2020	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Defined Contribution Plans [Abstract]
Number of 401(k) plans | plan	2
Paid discretionary contributions to defined contribution pension plans, company match	$ 5,500,000	$ 25,500,000		$ 27,800,000	$ 30,300,000
Discretionary contributions to defined contribution pension plans, granted				0
Payment of prior performance contributions		0		$ 8,900,000	$ 8,500,000
Additional discretionary contributions to defined contribution pension plans, performance feature	$ 0	$ 0
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Retirees Affected by Pension Settlement		1,950
Percentage of company's qualified pension plans on a GAAP accounting basis				80.00%
Expected long-term return on plan assets	5.90%	5.90%		4.20%	5.65%
Percentage of actuarial gains and losses amortized	5.00%
Defined Benefit Plan, Amortization Period | years	5
Defined Benefit Plan, Accumulated Benefit Obligation				$ 853,800,000	$ 795,900,000
Defined Contribution Plans [Abstract]
Additional discretionary contributions to defined contribution pension plans, performance feature				20,000,000.0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		$ 71,400,000
Pension obligations	$ 0	2,100,000		$ 0	$ 0
Fixed Income Investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				100.00%
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				1.00%	1.00%
Scenario, Forecast | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected long-term return on plan assets			3.60%
Australia
Defined Contribution Plans [Abstract]
Paid discretionary contributions to defined contribution pension plans, company match	6,100,000	$ 19,900,000		$ 26,500,000	$ 31,600,000
Payment of prior performance contributions				$ 3,000,000
Additional discretionary contributions to defined contribution pension plans, performance feature	$ 0				$ 3,000,000