Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance		$ 573,015
Balance, shares		32,200,000	32,100,000
Net income		$ 83,019	$ 32,585	$ 52,812
Balance		$ 608,280	$ 573,015
Balance, shares		32,300,000	32,200,000	32,100,000
Common Stock [Member] | Common Class A [Member]
Balance		$ 37	$ 37	$ 37
Balance, shares		37,396,000	37,319,000	37,239,000
Net income
Adoption of accounting standards	[1],[2]
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares		44,000	44,000	53,000
Options exercised
Options exercised, shares		10,000	33,000	26,000
Shares issued to Directors'
Shares issued to Directors', shares				1,000
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		$ 37	$ 37	$ 37
Balance, shares		37,450,000	37,396,000	37,319,000
Common Stock [Member] | Class B Preferred Stock [Member]
Balance		$ 3	$ 3	$ 3
Balance, shares		3,234,000	3,234,000	3,235,000
Net income
Adoption of accounting standards	[1],[2]
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares
Options exercised
Options exercised, shares
Shares issued to Directors'
Shares issued to Directors', shares				(1,000)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		$ 3	$ 3	$ 3
Balance, shares		3,234,000	3,234,000	3,234,000
Additional Paid-in Capital [Member]
Balance		$ 428,423	$ 425,953	$ 423,108
Net income
Adoption of accounting standards	[1],[2]
Compensation and benefits paid or payable in shares		1,437	1,564	1,980
Options exercised		201	597	667
Shares issued to Directors'		494	309	198
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		430,555	428,423	425,953
Retained Earnings [Member]
Balance		534,082	522,855	491,950
Net income		82,891	33,111	52,733
Adoption of accounting standards	[1],[2]	(5,068)
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared		(22,260)	(21,884)	(21,828)
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		589,645	534,082	522,855
Accumulated Other Comprehensive Income (Loss) [Member]
Balance		(135,901)	(184,189)	(158,844)
Net income
Adoption of accounting standards	[1],[2]
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared
Cumulative translation adjustments		(28,658)	45,980	(24,643)
Pension and postretirement liability adjustments		3,427	1,183	(2,994)
Derivative valuation adjustment		2,744	1,125	2,292
Balance		(158,388)	(135,901)	(184,189)
Treasury Stock [Member]
Balance		$ (256,876)	$ (257,136)	$ (257,391)
Balance, shares		8,431,000	8,443,000	8,455,000
Net income
Adoption of accounting standards	[1],[2]
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'		$ 273	$ 260	$ 255
Shares issued to Directors', shares		(12,000)	(12,000)	(12,000)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		$ (256,603)	$ (256,876)	$ (257,136)
Balance, shares		8,419,000	8,431,000	8,443,000
Noncontrolling Interest [Member]
Balance		$ 3,247	$ 3,767	$ 3,690
Net income		128	(526)	79
Adoption of accounting standards	[1],[2]	(327)
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared
Cumulative translation adjustments		(17)	6	(2)
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance		$ 3,031	$ 3,247	$ 3,767

[1] As described in Note 2, the Company adopted ASC 606 effective January 1, 2018, which resulted in a decrease to Retained earnings of $5.6 million and a $0.3 million decrease to Noncontrolling interest.

[2] As described in Note 7, the Company adopted ASU 2016-16 effective January 1, 2018, which resulted in a $0.5 million increase to Retained earnings.