Revenue from Contracts with Customers Deferred Revenues and Costs (Details) - Drilling Services [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Revenues and Costs, Classified
Current deferred revenues	$ 1,339	$ 1,722
Current deferred costs	1,071	1,543
Noncurrent deferred revenues	57	437
Noncurrent deferred costs	$ 267	$ 679