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	18,533		7,186			11,347
Repurchase of common shares	(4,777)					(4,777)
Dividends paid	(72,929)			(72,929)
Non-controlling interest additions	(10)						(10)
Amortization of deferred pension costs, net of tax	145				145
Interest rate swaps, net of tax	931				931
Net income	70,787			70,691			96
Balance at End of Period at Sep. 30, 2018	$ 161,412	1,148	61,649	171,617	(7,277)	(69,699)	3,974
Cash Dividends per Share	$ 1.65
Balance at Beginning of Period at Jun. 30, 2018	$ 157,774	1,148	58,927	173,499	(7,490)	(72,301)	3,991
Stock based-awards	6,141		2,722			3,419
Repurchase of common shares	(817)					(817)
Dividends paid	(24,294)			(24,294)
Non-controlling interest additions	(10)						(10)
Amortization of deferred pension costs, net of tax	48				48
Interest rate swaps, net of tax	165				165
Net income	22,405			22,412			(7)
Balance at End of Period at Sep. 30, 2018	$ 161,412	1,148	61,649	171,617	(7,277)	(69,699)	3,974
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	17,652		7,060			10,592
Repurchase of common shares	(1,502)					(1,502)
Dividends paid	(73,168)			(73,168)
Amortization of deferred pension costs, net of tax	(23)				(23)
Interest rate swaps, net of tax	(1,125)				(1,125)
Net income	91,827			91,653			174
Balance at End of Period at Sep. 30, 2019	$ 194,561	1,148	64,498	174,615	(6,604)	(43,411)	4,315
Cash Dividends per Share	$ 1.65
Balance at Beginning of Period at Jun. 30, 2019	$ 192,492	1,148	64,064	175,285	(6,359)	(45,877)	4,231
Stock based-awards	3,311		434			2,877
Repurchase of common shares	(411)					(411)
Dividends paid	(24,399)			(24,399)
Amortization of deferred pension costs, net of tax	(7)				(7)
Interest rate swaps, net of tax	(238)				(238)
Net income	23,813			23,729			84
Balance at End of Period at Sep. 30, 2019	$ 194,561	$ 1,148	$ 64,498	$ 174,615	$ (6,604)	$ (43,411)	$ 4,315
Cash Dividends per Share	$ 0.55