Changes in Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	$ 967,320	$ 867,543
Net income	27,369	27,086
Compensation and benefits paid or payable in shares	810	378
Cumulative translation adjustments	(12,070)	14,119
Pension and postretirement liability adjustments	382	(916)
Derivative valuation adjustment	(2,124)	(2,902)
Balance at end of the period	$ 973,565	$ 897,515
Dividends declared per Class A share (in dollars per share)	$ 0.26	$ 0.25
Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock, balance at the beginning of the period (in shares)	9,661,845
Dividends declared	$ (8,122)	$ (7,792)
Treasury stock, balance at the end of the period (in shares)	9,661,845
Dividends declared per Class A share (in dollars per share)	$ 0.26	$ 0.25
Common Stock | Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, balance at the beginning of the period (in shares)	40,856,000	40,785,000
Balance at start of the period	$ 41	$ 41
Compensation and benefits paid or payable in shares (in shares)	42,000	58,000
Common stock, balance at the end of the period (in shares)	40,898,000	40,842,000
Balance at end of the period	$ 41	$ 41
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	448,218	441,540
Compensation and benefits paid or payable in shares	810	378
Balance at end of the period	449,028	441,917
Retained  earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	1,010,942	931,318
Net income	27,291	26,889
Balance at end of the period	1,030,111	950,415
Retained  earnings | Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(8,122)	(7,792)
Accumulated items of other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	(133,168)	(144,927)
Cumulative translation adjustments	(12,116)	13,881
Pension and postretirement liability adjustments	382	(916)
Derivative valuation adjustment	(2,124)	(2,902)
Balance at end of the period	(147,026)	(134,864)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	$ (364,665)	$ (364,923)
Treasury stock, balance at the beginning of the period (in shares)	9,662,000	9,675,000
Balance at end of the period	$ (364,665)	$ (364,923)
Treasury stock, balance at the end of the period (in shares)	9,662,000	9,675,000
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at start of the period	$ 5,952	$ 4,494
Net income	78	197
Cumulative translation adjustments	46	238
Balance at end of the period	$ 6,076	$ 4,929