Condensed Consolidated Statements Of Equity Condensed Consolidatd Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock, Common	Additional Paid-in Capital	Retained Earnings	Foreign currency translation adjustments	Defined benefit pension adjustments
Balance (in shares) at Dec. 31, 2017		141,283
Balance at Dec. 31, 2017	$ 993,018	$ 1,413	$ 0	$ 867,699	$ 147,418	$ (22,593)	$ (919)
Shares issued under stock plans (in shares)		815
Shares issued under stock plans	(13,650)	$ 8	0	(13,658)	0	0	0
Share-based compensation expense	4,128	$ 0	0	4,128	0	0	0
Repurchase and retirements of common stock (in shares)		(296)
Repurchase and retirements of common stock	(9,999)	$ (3)	0	(1,809)	(8,187)	0	0
Dividends declared ($0.07 per share)	(9,913)	0	0	13	(9,926)	0	0
Pension liability adjustments	4	0	0	0	0	0	4
Foreign currency translation adjustments	3,835	0	0	0	0	3,835	0
Net income	57,562	$ 0	0	0	57,562	0	0
Balance (in shares) at Mar. 31, 2018		141,802
Balance at Mar. 31, 2018	1,024,394	$ 1,418	0	856,373	186,276	(18,758)	(915)
Balance (in shares) at Dec. 31, 2017		141,283
Balance at Dec. 31, 2017	993,018	$ 1,413	0	867,699	147,418	(22,593)	(919)
Pension liability adjustments	53
Foreign currency translation adjustments	(8,791)
Net income	111,911
Balance (in shares) at Jun. 30, 2018		141,691
Balance at Jun. 30, 2018	1,052,905	$ 1,417	0	861,357	222,381	(31,384)	(866)
Cumulative effect of change in accounting principle	(591)	$ 0	0	0	(591)	0	0
Balance (in shares) at Mar. 31, 2018		141,802
Balance at Mar. 31, 2018	1,024,394	$ 1,418	0	856,373	186,276	(18,758)	(915)
Shares issued under stock plans (in shares)		171
Shares issued under stock plans	2,264	$ 1	0	2,263	0	0	0
Share-based compensation expense	4,429	$ 0	0	4,429	0	0	0
Repurchase and retirements of common stock (in shares)		(282)
Repurchase and retirements of common stock	(10,001)	$ (2)	0	(1,708)	(8,291)	0	0
Dividends declared ($0.07 per share)	(9,953)	0	0	0	(9,953)	0	0
Pension liability adjustments	49	0	0	0	0	0	49
Foreign currency translation adjustments	(12,626)	0	0	0	0	(12,626)	0
Net income	54,349	$ 0	0	0	54,349	0	0
Balance (in shares) at Jun. 30, 2018		141,691
Balance at Jun. 30, 2018	1,052,905	$ 1,417	$ 0	861,357	222,381	(31,384)	(866)
Balance (in shares) at Dec. 31, 2018		136,179	(202)
Balance at Dec. 31, 2018	1,012,025	$ 1,362	$ (7,112)	837,658	213,753	(32,776)	(860)
Shares issued under stock plans (in shares)		572
Shares issued under stock plans	(6,812)	$ 5	0	(6,817)	0	0	0
Share-based compensation expense	4,653	$ 0	0	4,653	0	0	0
Repurchase and retirements of common stock (in shares)		(1,035)
Repurchase and retirements of common stock	(29,787)	$ (10)	0	(6,364)	(23,413)	0	0
Dividends declared ($0.07 per share)	(9,510)	0	0	7	(9,517)	0	0
Pension liability adjustments	24	0	0	0	0	0	24
Foreign currency translation adjustments	(2,787)	0	0	0	0	(2,787)	0
Net income	32,658	$ 0	$ 0	0	32,658	0	0
Balance (in shares) at Mar. 30, 2019		135,716	(202)
Balance at Mar. 30, 2019	1,000,464	$ 1,357	$ (7,112)	829,137	213,481	(35,563)	(836)
Balance (in shares) at Dec. 31, 2018		136,179	(202)
Balance at Dec. 31, 2018	1,012,025	$ 1,362	$ (7,112)	837,658	213,753	(32,776)	(860)
Pension liability adjustments	10
Foreign currency translation adjustments	(4,499)
Net income	156,655
Balance (in shares) at Jun. 29, 2019		135,343	(202)
Balance at Jun. 29, 2019	1,102,549	$ 1,353	$ (7,112)	830,922	315,511	(37,275)	(850)
Balance (in shares) at Mar. 30, 2019		135,716	(202)
Balance at Mar. 30, 2019	1,000,464	$ 1,357	$ (7,112)	829,137	213,481	(35,563)	(836)
Shares issued under stock plans (in shares)		49
Shares issued under stock plans	(572)	$ 0	0	(572)	0	0	0
Share-based compensation expense	4,936	$ 0	0	4,936	0	0	0
Repurchase and retirements of common stock (in shares)		(422)
Repurchase and retirements of common stock	(15,000)	$ (4)	0	(2,579)	(12,417)	0	0
Dividends declared ($0.07 per share)	(9,550)	0	0	0	(9,550)	0	0
Pension liability adjustments	(14)	0	0	0	0	0	(14)
Foreign currency translation adjustments	(1,712)	0	0	0	0	(1,712)	0
Net income	123,997	$ 0	$ 0	0	123,997	0	0
Balance (in shares) at Jun. 29, 2019		135,343	(202)
Balance at Jun. 29, 2019	$ 1,102,549	$ 1,353	$ (7,112)	$ 830,922	$ 315,511	$ (37,275)	$ (850)