Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Adjustments to goodwill during the measurement period			$ (2,205)	$ 0
Goodwill impairment	$ 0	$ 44,589	0	44,589	$ 37,120
Goodwill, impaired, accumulated impairment loss			81,709	81,709	37,120
Amortization expense for intangible assets			$ 12,427	$ 11,974	12,945
Transceivers
Goodwill [Line Items]
Goodwill impairment					19,325
Submarine Telecommunications
Goodwill [Line Items]
Goodwill impairment					$ 17,795