Revenue from Contracts with Customer (Narrative) (Details) - Drilling [Member]	6 Months Ended
	Jun. 30, 2019 contract
Segment Reporting Information [Line Items]
Number of Contracts, Daywork	24
Short-term Contract with Customer [Member]
Segment Reporting Information [Line Items]
Contract Duration	1 month
Long-term Contract with Customer [Member]
Segment Reporting Information [Line Items]
Contract Duration	3 years