Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Retained Earnings [Member]	Accumulated Other Comprehensive Income	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2019	$ 1,823,255	$ 185,101	$ (3,916)	$ 1,010,361	$ 601,903	$ 29,864	$ (58)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	50,799	0	0	0	81,941	(31,200)	58
Dividends, Common Stock	(34,414)	0	0	0	34,414	0	0
Stock option exercises	15,126	789	0	14,337	0	0	0
Restricted stock awards, net of forfeitures	0	168	0	(168)	0	0	0
Employee share-based compensation earned	3,406	0	0	3,406	0	0	0
Purchase of Company common stock	(123,102)	0	(2,901)	(16,202)	(103,999)	0	0
Other	(1,095)	0	0	(1,095)	0	0	0
Balance at end of period at Mar. 31, 2020	1,751,093	186,058	(6,817)	1,010,639	562,549	(1,336)	0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity, Period Increase (Decrease) | Accounting Standards Update 2016-13 [Member]	17,118	0	0	0	17,118	0	0
Balance at beginning of period at Dec. 31, 2019	1,823,255	185,101	(3,916)	1,010,361	601,903	29,864	(58)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	170,090
Balance at end of period at Jun. 30, 2020	1,754,328	186,105	(9,094)	1,002,988	561,882	12,400	47
Balance at beginning of period at Mar. 31, 2020	1,751,093	186,058	(6,817)	1,010,639	562,549	(1,336)	0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	119,291	0	0	0	105,508	13,736	47
Dividends, Common Stock	$ (33,719)	0	0	0	33,719	0	0
Dividends declared per share	$ 190
Employee share-based compensation earned	$ 3,638	0	0	3,638	0	0	0
Purchase of Company common stock	(87,466)	0	(2,277)	(12,862)	(72,327)	0	0
Other	1,620	47	0	1,573	0	0	0
Balance at end of period at Jun. 30, 2020	1,754,328	186,105	(9,094)	1,002,988	561,882	12,400	47
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity, Period Increase (Decrease) | Accounting Standards Update 2016-13 [Member]	(129)	0	0	0	(129)	0	0
Balance at beginning of period at Dec. 31, 2020	1,752,621	174,792	(4,075)	981,934	560,731	39,366	(127)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	233,960	0	0	0	228,879	5,005	76
Dividends, Common Stock	$ (35,568)	0	0	0	(35,568)	0	0
Dividends declared per share
Stock option exercises	$ 2,364	99	0	2,265	0	0	0
Restricted stock awards, net of forfeitures	0	163	0	(163)	0	0	0
Employee share-based compensation earned	3,500	0	0	3,500	0	0	0
Purchase of Company common stock	$ (106,217)	$ 0	$ (2,142)	$ (12,304)	$ (91,771)	$ 0	$ 0
Treasury Stock, Shares, Retired	0	(3,000)	(3,000)	0	0	0	0
Balance at end of period at Mar. 31, 2021	$ 1,850,660	$ 175,051	$ (6,214)	$ 975,232	$ 662,271	$ 44,371	$ (51)
Balance at beginning of period at Dec. 31, 2020	1,752,621	174,792	(4,075)	981,934	560,731	39,366	(127)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	398,683
Balance at end of period at Jun. 30, 2021	1,918,111	175,725	(7,756)	984,791	714,073	51,305	(27)
Balance at beginning of period at Mar. 31, 2021	1,850,660	175,051	(6,214)	975,232	662,271	44,371	(51)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	164,723	0	0	0	157,705	6,934	84
Dividends, Common Stock	$ (35,352)	0	0	0	(35,352)	0	0
Dividends declared per share	$ 210
Stock option exercises	$ 13,972	644	0	13,328	0	0	0
Restricted stock awards, net of forfeitures	0	(3)	0	3	0	0	0
Employee share-based compensation earned	3,596	0	0	3,596	0	0	0
Purchase of Company common stock	(81,048)	0	(1,542)	(8,955)	(70,551)	0	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	60	0	0	0	0	0	60
Other	1,620	33	0	1,587	0	0	0
Balance at end of period at Jun. 30, 2021	$ 1,918,111	$ 175,725	$ (7,756)	$ 984,791	$ 714,073	$ 51,305	$ (27)