CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock and Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Earnings (Loss)
Balance (in shares) at beginning of period at Dec. 31, 2014		139,579
Balance at beginning of period at Dec. 31, 2014	$ 1,609,773	$ 1,396	$ 1,671,786	$ (63,409)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	241,686		241,686
Income tax benefit of common stock options exercised	1,611	$ 1,611
Repurchase of common stock (in shares)		(4,169)
Repurchase of common stock	(123,193)	$ (44,387)	(78,806)
Common stock issued pursuant to stock-based compensation plans, net (in shares)		1,940
Common stock issued pursuant to stock-based compensation plans, net	17,071	$ 17,071
Stock-based compensation expense	25,683	$ 25,683
Dividends paid	(61,399)		(61,399)
Other comprehensive income (loss)	(61,717)			(61,717)
Balance (in shares) at end of period at Dec. 31, 2015		137,350
Balance at end of period at Dec. 31, 2015	1,649,515	$ 1,374	1,773,267	(125,126)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	166,626		166,626
Income tax benefit of common stock options exercised	1,329	$ 1,329
Repurchase of common stock (in shares)		(2,132)
Repurchase of common stock	(66,057)	$ (24,222)	(41,835)
Common stock issued pursuant to stock-based compensation plans, net (in shares)		1,116
Common stock issued pursuant to stock-based compensation plans, net	5,985	$ 5,985
Stock-based compensation expense	27,673	$ 27,673
Dividends paid	(65,920)		(65,920)
Other comprehensive income (loss)	(40,825)			(40,825)
Balance (in shares) at end of period at Dec. 31, 2016		136,334
Balance at end of period at Dec. 31, 2016	1,678,326	$ 12,139	1,832,138	(165,951)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	107,223		107,223
Common stock issued pursuant to stock-based compensation plans, net (in shares)		2,535
Common stock issued pursuant to stock-based compensation plans, net	47,510	$ 47,510
Stock-based compensation expense	31,513	$ 31,513
Dividends paid	(82,605)		(82,605)
Other comprehensive income (loss)	52,591			52,591
Balance (in shares) at end of period at Dec. 31, 2017		138,869
Balance at end of period at Dec. 31, 2017	$ 1,834,558	$ 91,162	$ 1,856,756	$ (113,360)