CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Unvested	Cumulative Effect, Period of Adoption, Adjustment	Common Stock and Additional Paid-in Capital	Common Stock and Additional Paid-in Capital Unvested	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Earnings (Loss)	Treasury Stock, Common	Treasury Stock, Common Unvested
Balance (in shares) at beginning of period at Dec. 31, 2017				138,869
Balance at beginning of period at Dec. 31, 2017	$ 1,834,558			$ 91,162		$ 1,856,756		$ (113,360)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	282,425		$ 80,280			282,425
Repurchase of common stock (in shares)				(4,986)
Repurchase of common stock	(243,706)			$ (136,891)		(106,815)
Stock Issued During Period, Value, Acquisitions	0
Common stock issued pursuant to stock-based compensation plans, net (in shares)				1,633
Common stock issued pursuant to stock-based compensation plans, net	12,896			$ 12,896
Stock-based compensation expense	34,188			$ 34,188
Dividends paid	(88,123)					(88,123)
Other comprehensive income (loss)	(35,732)							(35,732)
Balance (in shares) at end of period at Dec. 31, 2018				135,516
Balance at end of period at Dec. 31, 2018	1,876,786			$ 1,355		2,024,523		149,092
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	171,597		$ 3,439			171,597	$ 3,439
Repurchase of common stock (in shares)				(2,549)
Repurchase of common stock	(124,998)			$ (37,819)		(87,179)
Stock Issued During Period, Value, Acquisitions	0
Common stock issued pursuant to stock-based compensation plans, net (in shares)				1,427
Common stock issued pursuant to stock-based compensation plans, net	16,425			$ 16,425
Stock-based compensation expense	36,731			$ 36,731
Dividends paid	(91,694)					(91,694)
Other comprehensive income (loss)	(16,853)							(16,853)
Balance (in shares) at end of period at Dec. 31, 2019				134,394
Balance at end of period at Dec. 31, 2019	$ 1,871,433			$ 16,692		2,020,686		165,945
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock, Shares	0
Net earnings for the year	$ 212,584					212,584
Repurchase of common stock (in shares)	(4,600)			(4,115)					(450)
Repurchase of common stock	$ (166,311)			$ (23,380)		(126,629)			$ (16,302)
Stock Issued During Period, Value, Acquisitions	7,335	$ 0		$ 753	$ 2,216				$ 6,582	$ 2,216
Common stock issued pursuant to stock-based compensation plans, net (in shares)				1,081
Common stock issued pursuant to stock-based compensation plans, net	707			$ 707
Stock-based compensation expense	39,211			$ 39,211
Dividends paid	(89,544)					(89,544)
Other comprehensive income (loss)	7,959							7,959
Balance (in shares) at end of period at Dec. 31, 2020				131,360
Balance at end of period at Dec. 31, 2020	1,883,374			$ 31,767		$ 2,017,097		$ 157,986
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Acquisitions				182						61
Treasury Stock, Value	$ 7,504
Treasury Stock, Shares	207