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, 2018		$ 49,187	$ 118,234	$ 2,191,471	$ (288,447)	$ (539,664)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 135,665			135,665
Other Comprehensive Income (Loss), Net of Tax	12,214				12,214
Dividends paid/declared				(13,690)
Restricted stock			(5,491)			5,491
Stock options exercised			(1,822)			7,233
Other			(661)			661
Share-based compensation			6,575			405
Repurchases of common stock						(25,065)
Ending Balance at Jun. 30, 2019		49,187	116,835	2,339,703	(302,490)	(550,939)
Beginning Balance at Dec. 31, 2018		49,187	118,234	2,191,471	(288,447)	(539,664)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(10,570)
Ending Balance at Dec. 31, 2019	1,774,372	49,187	116,070	2,497,111	(325,274)	(562,722)
Beginning Balance at Mar. 31, 2019		49,187	114,696	2,266,902	(304,779)	(540,426)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	80,072			80,072
Other Comprehensive Income (Loss), Net of Tax	2,289				2,289
Dividends paid/declared				(7,271)
Stock options exercised			(1,303)			2,038
Share-based compensation			3,442			43
Repurchases of common stock						(12,594)
Ending Balance at Jun. 30, 2019		49,187	116,835	2,339,703	(302,490)	(550,939)
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02 [Member]				26,257	(26,257)
Beginning Balance at Dec. 31, 2019	1,774,372	49,187	116,070	2,497,111	(325,274)	(562,722)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	82,779			82,779
Other Comprehensive Income (Loss), Net of Tax	(17,407)				(17,407)
Dividends paid/declared				(14,163)
Restricted stock			(4,115)			4,115
Stock options exercised			106			5,081
Other			(517)			517
Share-based compensation			6,923			217
Repurchases of common stock						(124,613)
Ending Balance at Jun. 30, 2020	1,713,295	49,187	118,467	2,565,727	(342,681)	(677,405)
Beginning Balance at Mar. 31, 2020		49,187	114,911	2,541,777	(370,868)	(665,170)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	31,018			31,018
Other Comprehensive Income (Loss), Net of Tax	28,187				28,187
Dividends paid/declared				(7,068)
Stock options exercised			(244)			365
Share-based compensation			3,800			0
Repurchases of common stock						(12,600)
Ending Balance at Jun. 30, 2020	$ 1,713,295	$ 49,187	$ 118,467	$ 2,565,727	$ (342,681)	$ (677,405)