Summary Of Major Accounting Policies Long-lived asset impairments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) units	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		$ 68,763,000
Impairment of Long-Lived Assets Held-for-use	$ 0	$ 68,763,000	$ 68,763,000	$ 0
Minimum [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Alternative Investment, Measurement Input | units		0.11
Maximum [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Alternative Investment, Measurement Input | units		0.15
Weighted Average [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Alternative Investment, Measurement Input | units		0.12
Measurement Input, Long-term Revenue Growth Rate [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Alternative Investment, Measurement Input | units		0.02
Oceaneering AGV System [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		$ 1,150,000
Oceaneering Entertainment System [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		5,065,000
Global Data Solution [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		167,000
Ecosse [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		3,628,000
Shallow Water [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		3,894,000
Subsea Products Angola [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		38,482,000
SDS Brazil [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment property plant equipment		9,834,000
SDS Rosyth [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 6,543,000