FAIR VALUE MEASUREMENTS - Concentrations of Credit Risk (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 15, 2016
Concentration Risk [Line Items]
Contract liabilities, current	$ 16.7	$ 1.1
Jack-ups [Member] | Saudi Aramco [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	28.00%	29.00%	20.00%
Jack-ups [Member] | Saudi Aramco [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	21.00%	34.00%
Jack-ups [Member] | ConocoPhillips [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	2.00%	7.00%	11.00%
Jack-ups [Member] | ConocoPhillips [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	0.00%	8.00%
Jack-ups [Member] | BP Trinidad and Tobago [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	10.00%	6.00%	5.00%
Jack-ups [Member] | BP Trinidad and Tobago [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	9.00%	6.00%
Deepwater and Jack-up Segment [Member] | Freeport-McMoRan [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	1.00%	0.00%	12.00%
Deepwater and Jack-up Segment [Member] | Freeport-McMoRan [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	1.00%	0.00%
Deepwater and Jack-up Segment [Member] | Repsol [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	2.00%	7.00%	12.00%
Deepwater and Jack-up Segment [Member] | Repsol [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	4.00%	5.00%
Deepwater [Member] | Cobalt International [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	0.00%	14.00%	12.00%
Deepwater [Member] | Cobalt International [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	0.00%	0.00%
Deepwater [Member] | Anadarko [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	14.00%	17.00%	8.00%
Deepwater [Member] | Anadarko [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	0.00%	19.00%
Jack-ups and Unallocated and Other [Member] | ARO Drilling [Member] | Customer Concentration Risk [Member] | Consolidated Revenues [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	14.00%	1.00%	0.00%
Jack-ups and Unallocated and Other [Member] | ARO Drilling [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentrations of Credit Risk [Abstract]
Customer concentration, percentage	30.00%	9.00%
Rowan Reliance [Member] | Deferred Revenue [Domain] | Cobalt International [Member]
Concentration Risk [Line Items]
Contract liabilities, current				$ 95.9