Revenue from Contracts with Customers Deferred Revenues and Costs (Details) - Drilling Services [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Revenues and Costs, Classified
Current deferred revenues	$ 642	$ 1,339
Current deferred costs	201	1,071
Noncurrent deferred revenues	0	57
Noncurrent deferred costs	$ 30	$ 267