Unaudited Condensed Consolidated Statement of Equity Statement - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 172,232	$ 0	$ 0	$ 0	$ 172,461	$ (229)	$ 0
Balance at beginning of period at Dec. 31, 2017	1,409,437	191,936	(5,321)	970,468	210,364	41,943	47
Stockholders' Equity [Roll Forward]
Comprehensive income	72,456	0	0	0	81,988	(9,589)	57
Balance at end of period at Jun. 30, 2018	1,476,397	192,625	(11,387)	954,128	314,669	26,217	145
Balance at beginning of period at Dec. 31, 2017	1,409,437	191,936	(5,321)	970,468	210,364	41,943	47
Stockholders' Equity [Roll Forward]
Dividends declared on common stock	31,348	0	0	0	31,348	0	0
Employee share-based compensation earned	3,699	0	0	3,699	0	0	0
Stock option exercises	(4,989)	(282)	0	(4,707)	0	0	0
Restricted stock awards, net of forfeitures	0	163	0	(163)	0	0	0
Purchase of Company common stock	(118,797)	0	(3,095)	(16,101)	(99,601)	0	0
Other	(819)	47	0	(866)	0	0	0
Balance at end of period at Dec. 31, 2018	1,641,815	184,721	(3,250)	972,710	474,327	13,395	(88)
Balance at beginning of period at Mar. 31, 2018	1,511,849	192,428	(8,416)	961,744	333,864	32,125	104
Stockholders' Equity [Roll Forward]
Comprehensive income	97,372	0	0	0	103,239	(5,908)	41
Dividends declared on common stock	30,893	0	0	0	30,893	0	0
Employee share-based compensation earned	3,845	0	0	3,845	0	0	0
Stock option exercises	(2,313)	(129)	0	(2,184)	0	0	0
Restricted stock awards, net of forfeitures	0	15	0	(15)	0	0	0
Purchase of Company common stock	(110,069)	0	(2,971)	(15,557)	(91,541)	0	0
Other	1,980	53	0	1,927	0	0	0
Balance at end of period at Jun. 30, 2018	1,476,397	192,625	(11,387)	954,128	314,669	26,217	145
Balance at beginning of period at Dec. 31, 2018	1,641,815	184,721	(3,250)	972,710	474,327	13,395	(88)
Stockholders' Equity [Roll Forward]
Comprehensive income	86,614	0	0	0	79,323	7,251	40
Dividends declared on common stock	32,820	0	0	0	32,820	0	0
Employee share-based compensation earned	4,568	0	0	4,568	0	0	0
Stock option exercises	(15,962)	(950)	0	(15,012)	0	0	0
Restricted stock awards, net of forfeitures	0	126	0	(126)	0	0	0
Purchase of Company common stock	(14,542)	0	(355)	(1,935)	(12,252)	0	0
Other	(1,192)	59	0	(1,251)	0	0	0
Balance at end of period at Mar. 31, 2019	1,700,405	185,856	(3,605)	988,978	508,578	20,646	(48)
Stockholders' Equity [Roll Forward]
Comprehensive income	79,511	0	0	0	72,329	7,146	36
Dividends declared on common stock	32,871	0	0	0	32,871	0	0
Employee share-based compensation earned	3,445	0	0	3,445	0	0	0
Stock option exercises	(7,139)	(513)	0	(6,626)	0	0	0
Purchase of Company common stock	(15,032)	0	(337)	(1,832)	(12,863)	0	0
Other	1,619	42	0	1,577	0	0	0
Balance at end of period at Jun. 30, 2019	$ 1,744,216	$ 186,411	$ (3,942)	$ 998,794	$ 535,173	$ 27,792	$ (12)