Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Gross	$ 284,647,000	$ 293,948,000
Less accumulated depreciation	(231,098,000)	(222,407,000)
Property and equipment, net	53,549,000	71,541,000
Land, building and other
Property, Plant and Equipment
Gross	$ 16,611,000	$ 15,164,000
Land, building and other | Minimum
Property, Plant and Equipment
Estimated useful lives of property and equipment	3 years	3 years
Land, building and other | Maximum
Property, Plant and Equipment
Estimated useful lives of property and equipment	40 years	40 years
Recording equipment
Property, Plant and Equipment
Gross	$ 163,564,000	$ 171,514,000
Recording equipment | Minimum
Property, Plant and Equipment
Estimated useful lives of property and equipment	5 years	5 years
Recording equipment | Maximum
Property, Plant and Equipment
Estimated useful lives of property and equipment	10 years	10 years
Vibrator energy sources
Property, Plant and Equipment
Gross	$ 78,626,000	$ 79,168,000
Vibrator energy sources | Minimum
Property, Plant and Equipment
Estimated useful lives of property and equipment	5 years	5 years
Vibrator energy sources | Maximum
Property, Plant and Equipment
Estimated useful lives of property and equipment	15 years	15 years
Vehicles
Property, Plant and Equipment
Gross	$ 25,845,000	$ 28,101,000
Vehicles | Minimum
Property, Plant and Equipment
Estimated useful lives of property and equipment	1 year 6 months	1 year 6 months
Vehicles | Maximum
Property, Plant and Equipment
Estimated useful lives of property and equipment	10 years	10 years