Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred stock	Common stock	Common stock Common Class A	Additional paid-in capital	Other Additional paid in capital	Other Additional paid in capital Employee stock notes	Retained earnings	Accumulated other comprehensive income (loss)	Foreign currency adjustments	Unrealized (loss) gain on interest rate hedges	Net actuarial pension (loss) gain	Cumulative Effect, Period of Adoption, Adjustment Retained earnings
Balance at beginning of period, shares at Dec. 31, 2018		0		101,310,862
Balance at beginning of period at Dec. 31, 2018		$ 0		$ 1,013		$ 659,241	$ (648)	$ 246,833	$ (144,805)				$ 761
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards, shares				523,346
Shares issued for exercise/vesting of share-based compensation awards				$ 6		1,970
Shares repurchased (in shares)			(1,192,419)
Shares repurchased				$ (12)				(19,982)
Shares surrendered for tax obligations for employee share-based transactions, shares				(52,816)
Shares surrendered for tax obligations for employee share-based transactions				$ (1)		(1,057)
Amortization of share-based compensation						10,457
Net issuances, payments and accrued interest on notes							(19)
Net income	$ 55,175							55,175
Foreign currency adjustments	(38,600)									$ (38,600)
Unrealized (loss) gain on interest rate hedges	6,163										$ 6,163
Net actuarial pension gain	4,255											$ 4,255
Balance at end of period at Sep. 28, 2019	780,750			$ 1,006	$ 669,944	670,611	(667)	282,787	(172,987)
Balance at period end, shares at Sep. 28, 2019				100,588,973
Balance at beginning of period, shares at Jun. 29, 2019		0		100,543,160
Balance at beginning of period at Jun. 29, 2019		$ 0		$ 1,005		666,160	(661)	265,745	(142,777)
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards, shares				52,799
Shares issued for exercise/vesting of share-based compensation awards				$ 1		493
Shares repurchased (in shares)			0
Shares surrendered for tax obligations for employee share-based transactions, shares				(6,986)
Shares surrendered for tax obligations for employee share-based transactions						(139)
Amortization of share-based compensation						4,097
Net issuances, payments and accrued interest on notes							(6)
Net income	17,042							17,042
Foreign currency adjustments	(36,633)									(36,633)
Unrealized (loss) gain on interest rate hedges	5,050										5,050
Net actuarial pension gain	1,373											1,373
Balance at end of period at Sep. 28, 2019	780,750			$ 1,006	669,944	670,611	(667)	282,787	(172,987)
Balance at period end, shares at Sep. 28, 2019				100,588,973
Balance at beginning of period, shares at Dec. 31, 2019		0		100,668,003
Balance at beginning of period at Dec. 31, 2019	812,087	$ 0		$ 1,007		672,445	(673)	290,583	(151,275)				$ (5,710)
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards, shares				284,265
Shares issued for exercise/vesting of share-based compensation awards				$ 4		1,218
Shares repurchased (in shares)			(265,589)
Shares repurchased				$ (3)				(4,997)
Shares surrendered for tax obligations for employee share-based transactions, shares				(24,296)
Shares surrendered for tax obligations for employee share-based transactions				$ (1)		(464)
Amortization of share-based compensation						11,663
Net income	48,347							48,347
Foreign currency adjustments	29,136									29,136
Unrealized (loss) gain on interest rate hedges	(1,505)										(1,505)
Net actuarial pension gain	3,535											3,535
Balance at end of period at Sep. 26, 2020	893,310			$ 1,007	684,189	684,862	(673)	328,223	(120,109)
Balance at period end, shares at Sep. 26, 2020				100,662,383
Balance at beginning of period, shares at Jun. 27, 2020		0		100,553,258
Balance at beginning of period at Jun. 27, 2020		$ 0		$ 1,005		680,954	(673)	302,743	(153,427)
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards, shares				109,125
Shares issued for exercise/vesting of share-based compensation awards				$ 2		1,141
Shares repurchased (in shares)			0
Amortization of share-based compensation						2,767
Net income	25,480							25,480
Foreign currency adjustments	32,879									$ 32,879
Unrealized (loss) gain on interest rate hedges	(249)										$ (249)
Net actuarial pension gain	688											$ 688
Balance at end of period at Sep. 26, 2020	$ 893,310			$ 1,007	$ 684,189	$ 684,862	$ (673)	$ 328,223	$ (120,109)
Balance at period end, shares at Sep. 26, 2020				100,662,383