Reportable Segments - Reconciliation of Total Reportable Segments' Revenues and EBITDA to Consolidated Revenues and Consolidated Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment revenues	$ 637,530	$ 668,639	$ 1,224,705	$ 1,274,204
Amortization of intangibles	(22,368)	(25,039)	(45,709)	(49,457)
Depreciation expense	(12,300)	(12,000)	(25,000)	(23,900)
Severance, restructuring, and acquisition integration costs	(3,082)	(24,928)	(6,860)	(45,322)
Operating income	61,139	56,506	105,584	100,709
Interest expense, net	(14,168)	(15,088)	(28,361)	(32,066)
Non-operating pension benefit (cost)	481	(257)	1,028	(532)
Loss on debt extinguishment	0	(3,030)	0	(22,990)
Consolidated income before taxes	47,452	38,131	78,251	45,121
Reportable Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment revenues	637,530	671,441	1,224,705	1,278,864
Deferred revenue adjustments	0	(2,802)	0	(4,660)
Total Segment EBITDA	100,941	123,506	187,958	227,384
Amortization of intangibles	(22,368)	(25,039)	(45,709)	(49,457)
Depreciation expense	(12,301)	(12,026)	(25,021)	(23,891)
Severance, restructuring, and acquisition integration costs	(3,082)	(24,928)	(6,860)	(45,322)
Purchase accounting effects related to acquisitions	(718)	(1,036)	(2,031)	(1,538)
Amortization of software development intangible assets	(1,072)	(488)	(2,009)	(724)
Loss on sale of assets	0	0	0	(94)
Eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating income	$ (261)	(681)	$ (744)	(989)
Snell Advanced Media
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of intangibles		$ (2,800)		$ (5,000)