CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands		Total	Common Stock Member	Additional Paid In Capital Member	Retained Earnings Member	Accumulated Other Comprehensive Loss Member	Treasury Stock Member
Beginning Balance at Dec. 31, 2019			$ 49,187	$ 116,070	$ 2,497,111	$ (325,274)	$ (562,722)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		$ 147,399			147,399
Other Comprehensive Income (Loss), Net of Tax		14,383				14,383
Dividends paid					(21,221)
Restricted stock				(4,115)			4,115
Employee stock purchase plan and stock options exercised				(1,364)			11,272
Other				(517)			517
Share-based compensation				11,723			54
Repurchases of common stock	[1]						(137,155)
Ending Balance at Sep. 30, 2020			49,187	121,797	2,623,289	(310,891)	(683,919)
Beginning Balance at Dec. 31, 2019			49,187	116,070	2,497,111	(325,274)	(562,722)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax		14,418
Ending Balance at Dec. 31, 2020		1,787,574	49,187	122,535	2,670,328	(310,856)	(743,620)
Beginning Balance at Jun. 30, 2020			49,187	118,467	2,565,727	(342,681)	(677,405)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		64,620			64,620
Other Comprehensive Income (Loss), Net of Tax		31,790				31,790
Dividends paid					(7,058)
Employee stock purchase plan and stock options exercised				(1,470)			6,191
Share-based compensation				4,800			(163)
Repurchases of common stock	[1]						(12,542)
Ending Balance at Sep. 30, 2020			49,187	121,797	2,623,289	(310,891)	(683,919)
Beginning Balance at Dec. 31, 2020		1,787,574	49,187	122,535	2,670,328	(310,856)	(743,620)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		190,580			190,580
Other Comprehensive Income (Loss), Net of Tax		2,046				2,046
Dividends paid					(21,614)
Restricted stock				(9,007)			9,007
Employee stock purchase plan and stock options exercised				877			8,828
Other				(597)			597
Share-based compensation				10,724			137
Repurchases of common stock							(79,092)
Ending Balance at Sep. 30, 2021		1,900,060	49,187	124,532	2,839,294	(308,810)	(804,143)
Beginning Balance at Jun. 30, 2021			49,187	119,946	2,776,884	(297,531)	(753,782)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		69,703			69,703
Other Comprehensive Income (Loss), Net of Tax		(11,279)				(11,279)
Dividends paid					(7,293)
Employee stock purchase plan and stock options exercised				466			4,320
Share-based compensation				4,120			16
Repurchases of common stock							(54,697)
Ending Balance at Sep. 30, 2021		$ 1,900,060	$ 49,187	$ 124,532	$ 2,839,294	$ (308,810)	$ (804,143)

[1] For the three and nine months ended September 30, 2021, the Corporation repurchased approximately 0.4 million and 0.6 million shares of its common stock, respectively. For the three and nine months ended September 30, 2020, the Corporation repurchased approximately 0.1 million and 1.4 million shares of its common stock, respectively.