Consolidated Statements of Equity - USD ($)	Total	Preferred stock	Common stock	Common stock Common Class A	Additional paid-in capital	Employee stock notes	Employee stock notes Employee stock notes	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)	Foreign currency adjustments	Unrealized (loss) gain on interest rate hedges	Net actuarial pension (loss) gain
Balance at beginning of period at Dec. 31, 2017		$ 0		$ 1,060,000	$ 653,327,000		$ (661,000)	$ 229,903,000		$ (94,493,000)
Balance at beginning of period, shares at Dec. 31, 2017		0		105,990,483
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards				$ 8,000	189,000
Shares issued for exercise/vesting of share-based compensation awards, shares				761,568
Shares repurchased				$ (31,000)				(83,561,000)
Shares repurchased, shares				(3,080,594)
Shares surrendered for tax obligations for employee share-based transactions				$ (3,000)	(7,940,000)
Shares surrendered for tax obligations for employee share-based transactions, shares				(250,498)
Amortization of share-based compensation					12,017,000
Net issuances, payments and accrued interest on notes							19,000
Net income (loss) attributable to common shareholders	$ 103,817,000							103,817,000
Foreign currency adjustments	(47,779,000)									(47,779,000)
Unrealized gain on interest rate hedges	1,966,000										$ 1,966,000
Net actuarial pension gain	5,484,000											$ 5,484,000
Balance at end of period at Sep. 29, 2018	773,322,000			$ 1,034,000	657,593,000	$ 656,951,000	(642,000)	250,159,000	$ (134,822,000)
Balance at period end, shares at Sep. 29, 2018				103,420,959
Balance at beginning of period at Jun. 30, 2018		$ 0		$ 1,048,000	654,791,000		(635,000)	258,108,000		(126,622,000)
Balance at beginning of period, shares at Jun. 30, 2018		0		104,723,933
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards				$ 2,000	0
Shares issued for exercise/vesting of share-based compensation awards, shares				185,162
Shares repurchased				$ (15,000)				(36,586,000)
Shares repurchased, shares				(1,436,677)
Shares surrendered for tax obligations for employee share-based transactions				$ (1,000)	(1,257,000)
Shares surrendered for tax obligations for employee share-based transactions, shares				(51,459)
Amortization of share-based compensation					4,059,000
Net issuances, payments and accrued interest on notes							(7,000)
Net income (loss) attributable to common shareholders	28,637,000							28,637,000
Foreign currency adjustments	(10,277,000)
Unrealized gain on interest rate hedges	574,000
Net actuarial pension gain	1,503,000
Balance at end of period at Sep. 29, 2018	773,322,000			$ 1,034,000	657,593,000	656,951,000	(642,000)	250,159,000	(134,822,000)
Balance at period end, shares at Sep. 29, 2018				103,420,959
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standard ASU No. 2016-02 | ASU 2016-02								761,000
Balance at beginning of period at Dec. 31, 2018	$ 761,634,000	$ 0		$ 1,013,000	659,241,000		(648,000)	246,833,000		(144,805,000)
Balance at beginning of period, shares at Dec. 31, 2018		0		101,310,862
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards				$ 6,000	1,970,000
Shares issued for exercise/vesting of share-based compensation awards, shares				523,346
Shares repurchased				$ (12,000)				(19,982,000)
Shares repurchased, shares	(1,192,419)		(1,192,419)
Shares surrendered for tax obligations for employee share-based transactions				$ (1,000)	(1,057,000)
Shares surrendered for tax obligations for employee share-based transactions, shares				(52,816)
Amortization of share-based compensation					10,457,000
Net issuances, payments and accrued interest on notes							(19,000)
Net income (loss) attributable to common shareholders	$ 55,175,000							55,175,000
Foreign currency adjustments	(38,600,000)									(38,600,000)
Unrealized gain on interest rate hedges	6,163,000										$ 6,163,000
Net actuarial pension gain	4,255,000											$ 4,255,000
Balance at end of period at Sep. 28, 2019	780,750,000			$ 1,006,000	670,611,000	669,944,000	(667,000)	282,787,000	(172,987,000)
Balance at period end, shares at Sep. 28, 2019				100,588,973
Balance at beginning of period at Jun. 29, 2019		$ 0		$ 1,005,000	666,160,000		(661,000)	265,745,000		$ (142,777,000)
Balance at beginning of period, shares at Jun. 29, 2019		0		100,543,160
Increase (Decrease) in Stockholders' Equity
Shares issued for exercise/vesting of share-based compensation awards				$ 1,000	493,000
Shares issued for exercise/vesting of share-based compensation awards, shares				52,799
Shares repurchased				$ 0				0
Shares repurchased, shares			0
Shares surrendered for tax obligations for employee share-based transactions				$ 0	(139,000)
Shares surrendered for tax obligations for employee share-based transactions, shares				(6,986)
Amortization of share-based compensation					4,097,000
Net issuances, payments and accrued interest on notes							(6,000)
Net income (loss) attributable to common shareholders	17,042,000							17,042,000
Foreign currency adjustments	(36,633,000)
Unrealized gain on interest rate hedges	5,050,000
Net actuarial pension gain	1,373,000
Balance at end of period at Sep. 28, 2019	$ 780,750,000			$ 1,006,000	$ 670,611,000	$ 669,944,000	$ (667,000)	$ 282,787,000	$ (172,987,000)
Balance at period end, shares at Sep. 28, 2019				100,588,973