Retirement Benefits (Defined Benefit Pension Plans) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net periodic benefit cost:
Mark-to-market actuarial net losses	$ 14,000	$ 13,300
Amounts recognized in the balance sheet:
Accrued expenses and other current liabilities	(124,770)	(73,016)	$ (124,770)	$ (73,016)
Postretirement and pension liabilities	(181,610)	(174,021)	(181,610)	(174,021)
Pension Plan [Member]
Net periodic benefit cost:
Mark-to-market actuarial net losses			10,900	1,200	$ 16,600
Change in benefit obligation:
Actuarial loss (gain)					(17,900)
Fair value of plan assets at beginning of year			223,227
Fair value of plan assets at end of year	229,245	223,227	229,245	223,227
United States [Member] | Pension Plan [Member]
Net periodic benefit cost:
Service cost			10	10	11
Interest cost			9,479	11,787	11,308
Expected return on plan assets			(14,782)	(12,622)	(15,982)
Mark-to-market actuarial net losses			10,938	1,228	16,633
Special termination benefits			114
Net periodic benefit cost			5,759	403	11,970
Change in benefit obligation:
Benefit obligation at beginning of year			296,181	279,885
Service cost			10	10	11
Interest cost			9,479	11,787	11,308
Curtailments
Amendments
Settlements
Special termination benefits			114
Plan participants' contributions
Benefits paid			(21,119)	(19,978)
Actuarial loss (gain)			21,645	24,477
Exchange rate effect
Benefit obligation at end of year	306,310	296,181	306,310	296,181	279,885
Accumulated benefit obligation at end of year	306,310	296,181	306,310	296,181
Fair value of plan assets at beginning of year			223,227	204,425
Actual return on plan assets			25,489	35,871
Employer contributions			1,648	2,909
Plan participants' contributions
Benefits paid			(21,119)	(19,978)
Effect of settlements
Exchange rate effect
Fair value of plan assets at end of year	229,245	223,227	229,245	223,227	$ 204,425
Amounts recognized in the balance sheet:
Other non-current assets
Accrued expenses and other current liabilities	(389)	(410)	(389)	(410)
Postretirement and pension liabilities	(76,676)	(72,544)	(76,676)	(72,544)
Funded status	$ (77,065)	$ (72,954)	$ (77,065)	$ (72,954)
Weighted-average assumptions as of December 31:
Discount rate - net cost			3.35%	4.40%	3.80%
Discount rate - benefit obligations	2.55%	3.35%	2.55%	3.35%
Expected return on plan assets			7.70%	7.70%	7.70%
Pension plans with benefit obligations in excess of plan assets:
Benefit obligations	$ 306,310	$ 296,181	$ 306,310	$ 296,181
Plan assets	229,245	223,227	229,245	223,227
Pension plans with accumulated benefit obligations in excess of plan assets:
Projected benefit obligations	306,310	296,181	306,310	296,181
Accumulated benefit obligations	306,310	296,181	306,310	296,181
Plan assets	229,245	223,227	229,245	223,227
Prior service (cost):
Balance at beginning of year
Amounts recognized as net periodic benefit costs
Plan amendments
Exchange rate effects
Balance at end of year
Non-U.S. Pension Plans [Member] | Pension Plan [Member]
Net periodic benefit cost:
Service cost			1,555	1,410	1,392
Interest cost			1,788	2,264	2,166
Expected return on plan assets			(601)	(758)	(755)
Amortization of prior service cost			13	7	6
Mark-to-market actuarial net losses			2,977	11,033	2,444
Curtailment and settlement effects losses (gains)			66	292	156
Special termination benefits			26		106
Net periodic benefit cost			5,824	14,248	5,515
Change in benefit obligation:
Benefit obligation at beginning of year			116,698	106,098
Service cost			1,555	1,410	1,392
Interest cost			1,788	2,264	2,166
Curtailments				(45)
Amendments			(714)	23
Settlements			(835)	(734)
Special termination benefits			26
Plan participants' contributions				14
Benefits paid			(3,145)	(5,367)
Actuarial loss (gain)			4,907	14,949
Exchange rate effect			9,852	(1,914)
Benefit obligation at end of year	130,132	116,698	130,132	116,698	106,098
Accumulated benefit obligation at end of year	119,914	107,332	119,914	107,332
Fair value of plan assets at beginning of year			33,898	32,979
Actual return on plan assets			2,465	4,336
Employer contributions			2,363	3,277
Plan participants' contributions				14
Benefits paid			(3,145)	(5,367)
Effect of settlements			(835)	(734)
Exchange rate effect			2,841	(607)
Fair value of plan assets at end of year	37,587	33,898	37,587	33,898	$ 32,979
Amounts recognized in the balance sheet:
Other non-current assets	59	44	59	44
Accrued expenses and other current liabilities	(2,575)	(2,589)	(2,575)	(2,589)
Postretirement and pension liabilities	(90,029)	(80,255)	(90,029)	(80,255)
Funded status	$ (92,545)	$ (82,800)	$ (92,545)	$ (82,800)
Weighted-average assumptions as of December 31:
Discount rate - net cost			1.76%	2.61%	2.35%
Discount rate - benefit obligations	1.29%	1.76%	1.29%	1.76%
Rate of compensation increase - net cost			3.11%	3.19%	3.18%
Rate of compensation increase - benefit obligations	2.98%	3.11%	2.98%	3.11%
Expected return on plan assets			2.04%	2.74%	2.55%
Pension plans with benefit obligations in excess of plan assets:
Benefit obligations	$ 94,567	$ 84,791	$ 94,567	$ 84,791
Plan assets	1,963	1,946	1,963	1,946
Pension plans with accumulated benefit obligations in excess of plan assets:
Projected benefit obligations	94,057	84,338	94,057	84,338
Accumulated benefit obligations	83,923	75,073	83,923	75,073
Plan assets	1,518	1,553	1,518	1,553
Prior service (cost):
Balance at beginning of year			(44)	(22)
Amounts recognized as net periodic benefit costs			(13)	(7)
Plan amendments			(604)	(14)
Exchange rate effects			(11)	(1)
Balance at end of year	$ (672)	$ (44)	$ (672)	$ (44)	$ (22)