Pension Plans (Narrative) (Details) - USD ($)		12 Months Ended
	Jan. 01, 2005	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Type [Extensible List]		us-gaap:PensionPlansDefinedBenefitMember	us-gaap:PensionPlansDefinedBenefitMember
Interest rate used calculating annual transition pension adjustment for specified completed period of service	5.00%
Defined benefit plan, maximum number of years of completed service used in calculating the annual transition pension adjustment	35 years
Interest rate used calculating annual transition pension adjustment, thereafter	3.00%
Projected benefit obligation, defined benefit pension plans exceeded plan assets		$ 27,400,000
Expected rate of return on plan assets		4.75%
Defined Benefit Plan, Sponsor Location [Extensible List]		country:US	country:US
Period of fair value of plan assets amortized as a component of net periodic pension cost		5 years
Estimated future contributions in next fiscal year		$ 0
Maximum percentage contributed by employer		6.00%	6.00%	6.00%
Defined contribution plan expense		$ 24,100,000	$ 22,200,000	$ 21,700,000
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of unrecognized net actuarial gains (losses) as projected benefit obligation, amortized as component of net periodic pension cost		10.00%
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Type [Extensible List]		us-gaap:PensionPlansDefinedBenefitMember	us-gaap:PensionPlansDefinedBenefitMember
Expected rate of return on plan assets		4.75%	5.50%	4.75%
Defined Benefit Plan, Sponsor Location [Extensible List]		country:US	country:US	country:US
Actuarial (losses) gains		$ (25,900,000)	$ (20,400,000)
Estimated future contributions in next fiscal year			$ 10,000,000.0
Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Type [Extensible List]		us-gaap:PensionPlansDefinedBenefitMember	us-gaap:PensionPlansDefinedBenefitMember
Defined Benefit Plan, Sponsor Location [Extensible List]		country:US	country:US	country:US
Actuarial (losses) gains		$ (3,000,000.0)	$ 600,000
Estimated future contributions in next fiscal year		$ 2,900,000