Segment Information (Details) $ in Millions	3 Months Ended	6 Months Ended	10 Months Ended
Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Oct. 16, 2017 segment
Segment Reporting [Abstract]
Number of Operating Segments \| segment			3		2
Segment Reporting Information [Line Items]
Revenue	$ 241.3	$ 320.2	$ 452.5	$ 694.5
Operating expenses:
Direct operating costs (excluding items below)	176.3	168.8	333.7	340.1
Depreciation and amortization	97.4	101.5	195.3	200.6
Selling, general and administrative	25.2	22.2	50.8	46.4
Other operating items	2.2	3.1	3.5	6.5
Equity in earnings of unconsolidated subsidiary	1.6	0.0	0.3	0.0
INCOME (LOSS) FROM OPERATIONS	(58.2)	24.6	(130.5)	100.9
Deepwater Segment [Member]
Segment Reporting Information [Line Items]
Revenue	65.8	122.7	117.9	283.4
Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	166.6	197.5	316.7	411.1
Reporting Segments
Segment Reporting Information [Line Items]
Revenue	312.1	320.2	581.6	694.5
Operating expenses:
Direct operating costs (excluding items below)	212.2	168.8	403.0	340.1
Depreciation and amortization	114.2	101.5	228.7	200.6
Selling, general and administrative	32.0	22.2	64.0	46.4
Other operating items	3.1	3.1	4.5	6.5
Equity in earnings of unconsolidated subsidiary	0.0		0.0
INCOME (LOSS) FROM OPERATIONS	(49.4)	24.6	(118.6)	100.9
Reporting Segments \| Deepwater Segment [Member]
Segment Reporting Information [Line Items]
Revenue	65.8	122.7	117.9	283.4
Operating expenses:
Direct operating costs (excluding items below)	40.8	39.0	69.8	83.9
Depreciation and amortization	27.0	28.4	53.9	56.7
Selling, general and administrative	0.0	0.0	0.0	0.0
Other operating items	0.0	0.0	0.0	0.0
Equity in earnings of unconsolidated subsidiary	0.0		0.0
INCOME (LOSS) FROM OPERATIONS	(2.0)	55.3	(5.8)	142.8
Reporting Segments \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	166.6	197.5	316.7	411.1
Operating expenses:
Direct operating costs (excluding items below)	135.5	129.8	263.9	256.2
Depreciation and amortization	69.9	72.4	140.2	142.5
Selling, general and administrative	0.0	0.0	0.0	0.0
Other operating items	2.2	3.2	3.5	6.6
Equity in earnings of unconsolidated subsidiary	0.0		0.0
INCOME (LOSS) FROM OPERATIONS	(41.0)	(7.9)	(90.9)	5.8
Reporting Segments \| ARO Segment [Member]
Segment Reporting Information [Line Items]
Revenue	70.8	0.0	129.1	0.0
Operating expenses:
Direct operating costs (excluding items below)	35.9	0.0	69.3	0.0
Depreciation and amortization	16.8	0.0	33.4	0.0
Selling, general and administrative	6.8	0.0	13.2	0.0
Other operating items	0.9	0.0	1.0	0.0
Equity in earnings of unconsolidated subsidiary	0.0		0.0
INCOME (LOSS) FROM OPERATIONS	10.4	0.0	12.2	0.0
Unallocated and other
Segment Reporting Information [Line Items]
Revenue	8.9	0.0	17.9	0.0
Operating expenses:
Direct operating costs (excluding items below)	0.0	0.0	0.0	0.0
Depreciation and amortization	0.5	0.7	1.2	1.4
Selling, general and administrative	25.2	22.2	50.8	46.4
Other operating items	0.0	(0.1)	0.0	(0.1)
Equity in earnings of unconsolidated subsidiary	0.0		0.0
INCOME (LOSS) FROM OPERATIONS	(16.8)	(22.8)	(34.1)	(47.7)
Eliminations and adjustments
Segment Reporting Information [Line Items]
Revenue	(70.8)	0.0	(129.1)	0.0
Operating expenses:
Direct operating costs (excluding items below)	(35.9)	0.0	(69.3)	0.0
Depreciation and amortization	(16.8)	0.0	(33.4)	0.0
Selling, general and administrative	(6.8)	0.0	(13.2)	0.0
Other operating items	(0.9)	0.0	(1.0)	0.0
Equity in earnings of unconsolidated subsidiary	1.6		0.3
INCOME (LOSS) FROM OPERATIONS	(8.8)	0.0	(11.9)	0.0
Parent Company [Member] \| Saudi Arabia Joint Venture [Member]
Operating expenses:
Equity in earnings of unconsolidated subsidiary	$ 1.6		$ 0.3
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Saudi Arabia \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	$ 94.1	93.3	$ 182.0	187.5
Saudi Arabia \| Unallocated and other
Segment Reporting Information [Line Items]
Revenue	8.9	0.0	17.9	0.0
Norway \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	24.6	43.9	63.4	95.1
Trinidad \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	31.7	34.6	43.3	76.0
United Kingdom \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	11.5	13.7	21.9	29.2
United States \| Deepwater Segment [Member]
Segment Reporting Information [Line Items]
Revenue	65.8	120.3	117.9	281.0
United States \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	4.7	11.9	6.1	23.2
Other \| Deepwater Segment [Member]
Segment Reporting Information [Line Items]
Revenue	0.0	2.4	0.0	2.4
Other \| Jack-ups [Member]
Segment Reporting Information [Line Items]
Revenue	$ 0.0	$ 0.1	$ 0.0	$ 0.1
Saudi Aramco [Member] \| Saudi Arabia Joint Venture [Member]
Operating expenses:
Equity Method Investment, Ownership Percentage	50.00%		50.00%

Amount of expense for allocation of cost of tangible and intangible assets over their useful lives, and reduction in quantity of natural resource due to consumption directly used in production of good and rendering of service.

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