Operating Segments and Geographic Information - Reconciliation of Total Reportable Segments' Revenues and EBITDA to Consolidated Revenues and Consolidated Income Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Revenues and Consolidated Revenues	$ 2,408,100	$ 1,862,716	$ 2,131,278
Goodwill and other asset impairment	(140,461)	(113,007)	(521,441)
Depreciation expense	(45,900)	(42,500)	(40,400)
Amortization of intangibles	(38,346)	(64,395)	(74,609)
Severance, restructuring, and acquisition integration costs	(23,892)	(12,258)	(26,544)
Consolidated operating income	124,560	125,410	207,207
Interest expense, net	(62,695)	(58,888)	(55,814)
Non-operating pension benefit (cost)	4,476	(395)	1,017
Gain on sale of note receivable	27,036	0	0
Loss on debt extinguishment	(5,715)	0	0
Consolidated income from continuing operations before taxes	87,662	66,127	152,410
Proceeds from disposal of tangible assets	30,234	3,161	25
OTN Systems
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of intangibles	(5,100)
Reportable Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment EBITDA	371,182	246,959	353,035
Goodwill and other asset impairment	(140,461)	0	0
Depreciation expense	(45,940)	(42,470)	(40,409)
Amortization of intangibles	(38,346)	(64,395)	(74,609)
Severance, restructuring, and acquisition integration costs	(23,892)	(12,258)	(26,544)
Amortization of software development intangible assets	(2,900)	(1,821)	(525)
Purchase accounting effects related to acquisitions	5,036	(125)	(592)
Consolidated operating income	124,560	125,410	207,207
Interest expense, net	(62,695)	(58,888)	(55,814)
Deferred compensation - earnout payments	5,800
Proceeds from disposal of tangible assets	600
Reportable Segment | OTN Systems
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting effects related to acquisitions	2,300
Reportable Segment | Opterna International Corp.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Purchase accounting effects related to acquisitions		100	600
Reportable Segment | Grass Valley
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Recovery of accounts receivable previously written off	2,200
Eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Consolidated operating income	(119)	(480)	(3,149)
Segment revenues | Reportable Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Revenues and Consolidated Revenues	$ 2,408,100	$ 1,862,716	$ 2,131,278