Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Non-Controlling Interest
Balance at Beginning of Period at Dec. 31, 2016	$ 155,297	$ 1,148	$ 52,850	$ 187,957	$ (9,828)	$ (80,773)	$ 3,943
Balance at Beginning of Period (shares) at Dec. 31, 2016		44,796,252				644,991
Stock based-awards	22,942		1,529			$ 21,413
Stock based-awards (shares)						(191,513)
Repurchase of common shares	(16,909)					$ (16,909)
Repurchase of common shares (shares)						158,569
Dividends paid	(97,143)			(97,143)
Net income	83,096			83,125			(29)
Cumulative Effect of New Accounting Principle in Period of Adoption			84	(84)
Non-controlling interest additions	(26)						(26)
Amortization of deferred pension costs, net of tax	1,007				1,007
Interest rate swaps, net of tax	468				468
Balance at End of Period at Dec. 31, 2017	$ 148,732	$ 1,148	54,463	173,855	(8,353)	$ (76,269)	3,888
Balance at End of Period (shares) at Dec. 31, 2017		44,796,252				612,047
Cash Dividends per Share	$ 2.20
Stock based-awards	$ 34,194		2,975			$ 31,219
Stock based-awards (shares)						(218,625)
Repurchase of common shares	(7,451)					$ (7,451)
Repurchase of common shares (shares)						85,985
Dividends paid	(97,251)			(97,251)
Net income	79,789			79,526			263
Non-controlling interest additions	(10)						(10)
Amortization of deferred pension costs, net of tax	2,512				2,512
Interest rate swaps, net of tax	385				385
Balance at End of Period at Dec. 31, 2018	$ 160,900	$ 1,148	57,438	156,130	(5,456)	$ (52,501)	4,141
Balance at End of Period (shares) at Dec. 31, 2018		44,796,252				479,407
Cash Dividends per Share	$ 2.20
Stock based-awards	$ 20,879		(5,566)			$ 26,445
Stock based-awards (shares)	220,417					(220,417)
Repurchase of common shares	$ (3,308)					$ (3,308)
Repurchase of common shares (shares)						71,700
Dividends paid	(97,574)			(97,574)
Net income	102,117			101,983			134
Amortization of deferred pension costs, net of tax	10				10
Interest rate swaps, net of tax	(884)				(884)
Balance at End of Period at Dec. 31, 2019	$ 182,140	$ 1,148	$ 51,872	$ 160,539	$ (6,330)	$ (29,364)	$ 4,275
Balance at End of Period (shares) at Dec. 31, 2019		44,796,252				330,690
Cash Dividends per Share	$ 2.20