Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI Attributable to Parent	Treasury Stock	Noncontrolling Interest
Balance at Beginning of Period at Dec. 31, 2017	$ 148,732	$ 1,148	$ 54,463	$ 173,855	$ (8,353)	$ (76,269)	$ 3,888
Stock based-awards	12,392		4,464			7,928
Repurchase of common shares	(3,960)					(3,960)
Dividends paid	(48,635)			(48,635)
Amortization of deferred pension costs, net of tax	97				97
Interest rate swaps, net of tax	766				766
Net income	48,382			48,279			103
Balance at End of Period at Jun. 30, 2018	$ 157,774	1,148	58,927	173,499	(7,490)	(72,301)	3,991
Cash Dividends per Share	$ 1.10
Balance at Beginning of Period at Mar. 31, 2018	$ 151,576	1,148	55,670	173,060	(7,745)	(74,495)	3,938
Stock based-awards	6,101		3,257			2,844
Repurchase of common shares	(650)					(650)
Dividends paid	(24,313)			(24,313)
Amortization of deferred pension costs, net of tax	49				49
Interest rate swaps, net of tax	206				206
Net income	24,805			24,752			53
Balance at End of Period at Jun. 30, 2018	$ 157,774	1,148	58,927	173,499	(7,490)	(72,301)	3,991
Cash Dividends per Share	$ 0.55
Balance at Beginning of Period at Dec. 31, 2018	$ 160,900	1,148	57,438	156,130	(5,456)	(52,501)	4,141
Stock based-awards	14,341		6,626			7,715
Repurchase of common shares	(1,091)					(1,091)
Dividends paid	(48,769)			(48,769)
Amortization of deferred pension costs, net of tax	(16)				(16)
Interest rate swaps, net of tax	(887)				(887)
Net income	68,014			67,924			90
Balance at End of Period at Jun. 30, 2019	$ 192,492	1,148	64,064	175,285	(6,359)	(45,877)	4,231
Cash Dividends per Share	$ 1.10
Balance at Beginning of Period at Mar. 31, 2019	$ 187,353	1,148	65,084	172,266	(5,795)	(49,538)	4,188
Stock based-awards	3,245		(1,020)			4,265
Repurchase of common shares	(604)					(604)
Dividends paid	(24,395)			(24,395)
Amortization of deferred pension costs, net of tax	(9)				(9)
Interest rate swaps, net of tax	(555)				(555)
Net income	27,457			27,414			43
Balance at End of Period at Jun. 30, 2019	$ 192,492	$ 1,148	$ 64,064	$ 175,285	$ (6,359)	$ (45,877)	$ 4,231
Cash Dividends per Share	$ 0.55