Consolidated Statement of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Accumulated Other Comprehensive Income	Retained Earnings [Member]	Noncontrolling Interest	Adjustments for New Accounting Pronouncement [Member]	Adjustments for New Accounting Pronouncement [Member] Common Stock	Adjustments for New Accounting Pronouncement [Member] Treasury Stock	Adjustments for New Accounting Pronouncement [Member] Capital in Excess of Par Value	Adjustments for New Accounting Pronouncement [Member] Accumulated Other Comprehensive Income	Adjustments for New Accounting Pronouncement [Member] Retained Earnings [Member]	Adjustments for New Accounting Pronouncement [Member] Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2017	$ 1,409,437	$ 191,936	$ (5,321)	$ 970,468	$ 41,943	$ 210,364	$ 47
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity, Period Increase (Decrease)								$ 172,232	$ 0	$ 0	$ 0	$ (229)	$ 172,461	$ 0
Comprehensive income	419,080	0	0	0	(28,319)	447,208	191
Dividends	(123,849)	0	0	0	0	(123,849)
Stock option exercises	24,517	1,802	0	22,715	0	0	0
Restricted stock awards, net of forfeitures	0	178	0	(178)	0	0	0
Employee share-based compensation earned	15,626	0	0	15,626	0	0	0
Purchase of Company common stock	277,611	0	7,348	38,404	0	231,859	0
Noncontrolling interest payments	$ (326)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (326)
Retirement of treasury shares	0	(9,419)	(9,419)	0	0	0	0
Other	$ 2,709	$ 224	$ 0	$ 2,483	$ 0	$ 2	$ 0
Balance at end of period at Dec. 31, 2018	1,641,815	184,721	(3,250)	972,710	13,395	474,327	(88)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	386,241	0	0	0	16,469	369,596	176
Dividends	(131,402)	0	0	0	0	(131,402)
Stock option exercises	40,922	2,394	0	38,528	0	0	0
Restricted stock awards, net of forfeitures	0	126	0	(126)	0	0	0
Employee share-based compensation earned	15,029	0	0	15,029	0	0	0
Purchase of Company common stock	129,589	0	2,909	16,062	0	110,618	0
Noncontrolling interest payments	$ (146)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (146)
Retirement of treasury shares	0	(2,243)	(2,243)	0	0	0	0
Other	$ 385	$ 103	$ 0	$ 282	$ 0	$ 0	$ 0
Balance at end of period at Dec. 31, 2019	1,823,255	185,101	(3,916)	1,010,361	29,864	601,903	(58)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity, Period Increase (Decrease)								$ 16,989	$ 0	$ 0	$ 0	$ 0	$ 16,989	$ 0
Comprehensive income	525,644	0	0	0	9,502	515,907	235
Dividends	(137,392)	0	0	0	0	(137,392)
Stock option exercises	26,671	1,361	0	25,310	0	0	0
Restricted stock awards, net of forfeitures	0	170	0	(170)	0	0	0
Employee share-based compensation earned	14,103	0	0	14,103	0	0	0
Purchase of Company common stock	516,870	0	12,043	68,151	0	436,676	0
Noncontrolling interest payments	$ (304)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 304
Retirement of treasury shares	0	(11,884)	(11,884)	0	0	0	0
Other	$ 525	$ 44	$ 0	$ 481	$ 0	$ 0	$ 0
Balance at end of period at Dec. 31, 2020	$ 1,752,621	$ 174,792	$ (4,075)	$ 981,934	$ 39,366	$ 560,731	$ (127)