Fair Value Measurements - Concentration of Credit Risk (Details) - Customer Concentration Risk [Member]	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Deepwater Segment [Member] | Anadarko [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	20.00%		19.00%
Deepwater Segment [Member] | Anadarko [Member] | Sales Revenue, Services, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	26.00%	15.00%
Deepwater Segment [Member] | Repsol [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%		5.00%
Deepwater Segment [Member] | Repsol [Member] | Sales Revenue, Services, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	1.00%	10.00%
Deepwater Segment [Member] | Cobalt International [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%		0.00%
Deepwater Segment [Member] | Cobalt International [Member] | Sales Revenue, Services, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%	16.00%
Jack-ups [Member] | Saudi Aramco [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	41.00%		34.00%
Jack-ups [Member] | Saudi Aramco [Member] | Sales Revenue, Services, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	35.00%	27.00%
Jack-ups [Member] | Lundin [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	7.00%		7.00%
Jack-ups [Member] | Lundin [Member] | Sales Revenue, Services, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	10.00%	7.00%