Guarantees of Registered Securities - Condensed Consolidating Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 1,037.5	$ 290.5	$ 484.2	$ 339.2	$ 1,037.5	$ 484.2
Receivables - trade and other					440.5	410.5
Prepaid expenses and other current assets					28.6	26.6
Total current assets					1,506.6	921.3
Property and equipment - gross					9,090.4	9,068.1
Less accumulated depreciation and amortization					1,947.1	1,662.3
Property and equipment - net					7,143.3	7,405.8
Investments in subsidiaries					0.0	0.0
Due from affiliates					0.0	0.0
Other assets					15.1	20.2
TOTAL ASSETS					8,665.0	8,347.3
CURRENT LIABILITIES:
Current portion of long-term debt					357.1	0.0
Accounts payable - trade					82.2	109.6
Deferred revenues					78.4	33.1
Accrued liabilities					160.1	186.0
Total current liabilities					677.8	328.7
Long-term debt, less current portion					2,288.5	2,692.4
Due to affiliates					0.0	0.0
Other liabilities					356.7	357.9
Deferred income taxes - net					184.8	195.8
Shareholders' equity					5,157.2	4,772.5
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY					8,665.0	8,347.3
Condensed Consolidating Income Statements
REVENUES	379.4	545.4	1,491.4	1,601.2
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	186.0	247.6	598.3	757.3
Depreciation and amortization	102.2	104.1	301.2	289.2
Selling, general and administrative	23.5	29.7	76.5	88.4
Loss on disposals of property and equipment	1.2	2.3	5.3	2.1
Material charges and other operating items	32.9	332.3	32.9	337.3
Total costs and expenses	345.8	716.0	1,014.2	1,474.3
Income (loss) from operations	33.6	(170.6)	477.2	126.9
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	(39.4)	(41.3)	(116.6)	(104.9)
Interest income	1.2	0.2	2.1	0.8
Gain on extinguishment of debt	0.0	0.0	2.4	0.0
Other - net	(2.1)	(1.8)	(5.4)	(2.9)
Total other income (expense), net	(40.3)	(42.9)	(117.5)	(107.0)
INCOME (LOSS) BEFORE INCOME TAXES	(6.7)	(213.5)	359.7	19.9
Provision (benefit) for income taxes	(12.2)	25.9	14.7	50.9
Equity in earnings of subsidiaries, net of tax	0.0	0.0	0.0	0.0
NET INCOME (LOSS)	5.5	(239.4)	345.0	(31.0)
Statements of Comprehensive Income (Loss)
NET INCOME (LOSS)	5.5	(239.4)	345.0	(31.0)
OTHER COMPREHENSIVE INCOME:
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income taxes	19.2	0.0	19.2	0.0
Net reclassification adjustments for amount recognized in net income (loss) as a component of net periodic benefit cost, net of income taxes	1.0	3.4	6.0	10.2
OTHER COMPREHENSIVE INCOME	20.2	3.4	25.2	10.2
COMPREHENSIVE INCOME (LOSS)	25.7	(236.0)	370.2	(20.8)
Consolidating Statements of Cash Flows
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES			688.6	658.9
INVESTING ACTIVITIES:
Capital expenditures			(88.5)	(674.8)
Proceeds from disposals of property and equipment			1.1	5.1
Advances on subsidiary notes receivables				0.0
Collections on subsidiary notes receivables			0.0	0.0
Investments in consolidated subsidiaries			0.0	0.0
Net cash provided by (used in) investing activities			(87.4)	(669.7)
FINANCING ACTIVITIES:
Advances (to) from affiliates			0.0	0.0
Contributions from issuer			0.0	0.0
Proceeds from borrowings			0.0	220.0
Reductions of long-term debt			(47.9)	(220.0)
Dividends paid			0.0	(37.9)
Net cash provided by (used in) financing activities			(47.9)	(37.9)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			553.3	(48.7)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			484.2	339.2
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,037.5	290.5	1,037.5	290.5
Consolidating adjustments [Member]
CURRENT ASSETS:
Cash and cash equivalents	0.0	0.0	0.0	0.0	0.0	0.0
Receivables - trade and other					0.0	0.0
Prepaid expenses and other current assets					0.0	0.0
Total current assets					0.0	0.0
Property and equipment - gross					0.0	0.0
Less accumulated depreciation and amortization					0.0	0.0
Property and equipment - net					0.0	0.0
Investments in subsidiaries					(11,342.7)	(10,791.5)
Due from affiliates					(637.8)	(1,274.6)
Other assets					0.0	0.0
TOTAL ASSETS					(11,980.5)	(12,066.1)
CURRENT LIABILITIES:
Current portion of long-term debt					0.0
Accounts payable - trade					0.0	0.0
Deferred revenues					0.0	0.0
Accrued liabilities					0.0	0.0
Total current liabilities					0.0	0.0
Long-term debt, less current portion					0.0	0.0
Due to affiliates					(637.8)	(1,274.6)
Other liabilities					0.0	0.0
Deferred income taxes - net					(499.5)	(477.9)
Shareholders' equity					(10,843.2)	(10,313.6)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY					(11,980.5)	(12,066.1)
Condensed Consolidating Income Statements
REVENUES	(4.5)	(14.0)	(37.9)	(48.0)
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	(3.3)	(12.8)	(33.9)	(44.5)
Depreciation and amortization	0.2	0.1	0.7	0.8
Selling, general and administrative	(1.4)	(1.3)	(4.7)	(4.3)
Loss on disposals of property and equipment	0.0	0.0	0.0	0.0
Material charges and other operating items	0.0	0.0	0.0	0.0
Total costs and expenses	(4.5)	(14.0)	(37.9)	(48.0)
Income (loss) from operations	0.0	0.0	0.0	0.0
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	0.6	14.0	3.7	20.5
Interest income	(0.6)	(14.0)	(3.7)	(20.5)
Gain on extinguishment of debt			0.0
Other - net	0.0	0.0	0.0	0.0
Total other income (expense), net	0.0	0.0	0.0	0.0
INCOME (LOSS) BEFORE INCOME TAXES	0.0	0.0	0.0	0.0
Provision (benefit) for income taxes	(4.1)	12.9	(21.9)	(6.8)
Equity in earnings of subsidiaries, net of tax	152.3	422.2	(379.5)	190.5
NET INCOME (LOSS)	156.4	409.3	(357.6)	197.3
Statements of Comprehensive Income (Loss)
NET INCOME (LOSS)	156.4	409.3	(357.6)	197.3
OTHER COMPREHENSIVE INCOME:
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income taxes	(19.2)		(19.2)
Net reclassification adjustments for amount recognized in net income (loss) as a component of net periodic benefit cost, net of income taxes	(1.0)	(3.4)	(6.0)	(10.2)
OTHER COMPREHENSIVE INCOME	(20.2)		(25.2)
COMPREHENSIVE INCOME (LOSS)	136.2	405.9	(382.8)	187.1
Consolidating Statements of Cash Flows
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES			(78.5)	(47.5)
INVESTING ACTIVITIES:
Capital expenditures			0.0	0.0
Proceeds from disposals of property and equipment			0.0	0.0
Advances on subsidiary notes receivables				481.3
Collections on subsidiary notes receivables			(580.8)	(441.2)
Investments in consolidated subsidiaries			204.8	36.7
Net cash provided by (used in) investing activities			(376.0)	76.8
FINANCING ACTIVITIES:
Advances (to) from affiliates			(1.2)	(1.5)
Contributions from issuer			(204.8)	(36.7)
Proceeds from borrowings				(481.3)
Reductions of long-term debt			580.8	441.2
Dividends paid			79.7	49.0
Net cash provided by (used in) financing activities			454.5	(29.3)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			0.0	0.0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			0.0	0.0
CASH AND CASH EQUIVALENTS, END OF PERIOD	0.0	0.0	0.0	0.0
Rowan plc (Parent) [Member]
CURRENT ASSETS:
Cash and cash equivalents	5.1	0.8	17.3	45.9	5.1	17.3
Receivables - trade and other					0.0	0.1
Prepaid expenses and other current assets					0.5	0.4
Total current assets					5.6	17.8
Property and equipment - gross					0.0	0.0
Less accumulated depreciation and amortization					0.0	0.0
Property and equipment - net					0.0	0.0
Investments in subsidiaries					5,155.9	4,763.3
Due from affiliates					0.7	0.6
Other assets					0.0	0.0
TOTAL ASSETS					5,162.2	4,781.7
CURRENT LIABILITIES:
Current portion of long-term debt					0.0
Accounts payable - trade					0.6	1.0
Deferred revenues					0.0	0.0
Accrued liabilities					0.3	0.7
Total current liabilities					0.9	1.7
Long-term debt, less current portion					0.0	0.0
Due to affiliates					0.1	2.9
Other liabilities					4.0	4.6
Deferred income taxes - net					0.0	0.0
Shareholders' equity					5,157.2	4,772.5
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY					5,162.2	4,781.7
Condensed Consolidating Income Statements
REVENUES	0.0	0.0	0.0	0.0
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	0.0	0.0	0.0	0.0
Depreciation and amortization	0.0	0.0	0.0	0.0
Selling, general and administrative	5.7	5.5	19.5	16.7
Loss on disposals of property and equipment	0.0	0.0	0.0	0.0
Material charges and other operating items	0.0	0.0	0.0	0.0
Total costs and expenses	5.7	5.5	19.5	16.7
Income (loss) from operations	(5.7)	(5.5)	(19.5)	(16.7)
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	0.0	0.0	0.0	0.0
Interest income	0.0	0.6	0.0	0.8
Gain on extinguishment of debt			0.0
Other - net	5.4	5.6	15.8	16.8
Total other income (expense), net	5.4	6.2	15.8	17.6
INCOME (LOSS) BEFORE INCOME TAXES	(0.3)	0.7	(3.7)	0.9
Provision (benefit) for income taxes	0.0	0.0	0.0	0.0
Equity in earnings of subsidiaries, net of tax	5.8	(240.1)	348.7	(31.9)
NET INCOME (LOSS)	5.5	(239.4)	345.0	(31.0)
Statements of Comprehensive Income (Loss)
NET INCOME (LOSS)	5.5	(239.4)	345.0	(31.0)
OTHER COMPREHENSIVE INCOME:
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income taxes	19.2		19.2
Net reclassification adjustments for amount recognized in net income (loss) as a component of net periodic benefit cost, net of income taxes	1.0	3.4	6.0	10.2
OTHER COMPREHENSIVE INCOME	20.2		25.2
COMPREHENSIVE INCOME (LOSS)	25.7	(236.0)	370.2	(20.8)
Consolidating Statements of Cash Flows
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES			(9.2)	(3.7)
INVESTING ACTIVITIES:
Capital expenditures			0.0	0.0
Proceeds from disposals of property and equipment			0.0	0.0
Advances on subsidiary notes receivables				0.0
Collections on subsidiary notes receivables			0.0	7.0
Investments in consolidated subsidiaries			(0.2)	0.0
Net cash provided by (used in) investing activities			(0.2)	7.0
FINANCING ACTIVITIES:
Advances (to) from affiliates			(2.8)	(10.5)
Contributions from issuer			0.0	0.0
Proceeds from borrowings				0.0
Reductions of long-term debt			0.0	0.0
Dividends paid			0.0	(37.9)
Net cash provided by (used in) financing activities			(2.8)	(48.4)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			(12.2)	(45.1)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			17.3	45.9
CASH AND CASH EQUIVALENTS, END OF PERIOD	5.1	0.8	5.1	0.8
RCI (Issuer) [Member]
CURRENT ASSETS:
Cash and cash equivalents	359.8	18.2	9.5	48.6	359.8	9.5
Receivables - trade and other					1.3	1.4
Prepaid expenses and other current assets					18.4	19.3
Total current assets					379.5	30.2
Property and equipment - gross					616.5	592.8
Less accumulated depreciation and amortization					264.6	242.7
Property and equipment - net					351.9	350.1
Investments in subsidiaries					6,186.8	6,028.2
Due from affiliates					578.9	1,218.2
Other assets					4.8	5.0
TOTAL ASSETS					7,501.9	7,631.7
CURRENT LIABILITIES:
Current portion of long-term debt					357.1
Accounts payable - trade					18.9	19.1
Deferred revenues					0.0	0.0
Accrued liabilities					90.1	119.4
Total current liabilities					466.1	138.5
Long-term debt, less current portion					2,288.5	2,692.4
Due to affiliates					59.1	55.8
Other liabilities					277.2	304.7
Deferred income taxes - net					540.3	522.9
Shareholders' equity					3,870.7	3,917.4
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY					7,501.9	7,631.7
Condensed Consolidating Income Statements
REVENUES	5.4	15.9	41.3	49.2
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	(2.0)	1.0	5.2	5.8
Depreciation and amortization	5.3	6.8	14.0	14.8
Selling, general and administrative	0.0	(1.8)	0.0	0.3
Loss on disposals of property and equipment	0.5	0.5	0.6	0.5
Material charges and other operating items	0.0	0.0	0.0	0.0
Total costs and expenses	3.8	6.5	19.8	21.4
Income (loss) from operations	1.6	9.4	21.5	27.8
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	(39.4)	(41.3)	(116.6)	(104.9)
Interest income	1.0	13.1	4.2	19.7
Gain on extinguishment of debt			2.4
Other - net	(5.4)	(5.7)	(15.8)	(16.8)
Total other income (expense), net	(43.8)	(33.9)	(125.8)	(102.0)
INCOME (LOSS) BEFORE INCOME TAXES	(42.2)	(24.5)	(104.3)	(74.2)
Provision (benefit) for income taxes	(2.9)	24.8	19.3	27.2
Equity in earnings of subsidiaries, net of tax	(158.1)	(182.1)	30.8	(158.6)
NET INCOME (LOSS)	(197.4)	(231.4)	(92.8)	(260.0)
Statements of Comprehensive Income (Loss)
NET INCOME (LOSS)	(197.4)	(231.4)	(92.8)	(260.0)
OTHER COMPREHENSIVE INCOME:
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income taxes	19.2		19.2
Net reclassification adjustments for amount recognized in net income (loss) as a component of net periodic benefit cost, net of income taxes	1.0	3.4	6.0	10.2
OTHER COMPREHENSIVE INCOME	20.2		25.2
COMPREHENSIVE INCOME (LOSS)	(177.2)	(228.0)	(67.6)	(249.8)
Consolidating Statements of Cash Flows
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES			(27.8)	22.6
INVESTING ACTIVITIES:
Capital expenditures			(31.2)	(14.8)
Proceeds from disposals of property and equipment			0.4	2.8
Advances on subsidiary notes receivables				(481.3)
Collections on subsidiary notes receivables			580.8	434.2
Investments in consolidated subsidiaries			(204.6)	(36.7)
Net cash provided by (used in) investing activities			345.4	(95.8)
FINANCING ACTIVITIES:
Advances (to) from affiliates			80.6	42.8
Contributions from issuer			0.0	0.0
Proceeds from borrowings				220.0
Reductions of long-term debt			(47.9)	(220.0)
Dividends paid			0.0	0.0
Net cash provided by (used in) financing activities			32.7	42.8
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			350.3	(30.4)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			9.5	48.6
CASH AND CASH EQUIVALENTS, END OF PERIOD	359.8	18.2	359.8	18.2
Non-guarantor subsidiaries [Member]
CURRENT ASSETS:
Cash and cash equivalents	672.6	271.5	457.4	244.7	672.6	457.4
Receivables - trade and other					439.2	409.0
Prepaid expenses and other current assets					9.7	6.9
Total current assets					1,121.5	873.3
Property and equipment - gross					8,473.9	8,475.3
Less accumulated depreciation and amortization					1,682.5	1,419.6
Property and equipment - net					6,791.4	7,055.7
Investments in subsidiaries					0.0	0.0
Due from affiliates					58.2	55.8
Other assets					10.3	15.2
TOTAL ASSETS					7,981.4	8,000.0
CURRENT LIABILITIES:
Current portion of long-term debt					0.0
Accounts payable - trade					62.7	89.5
Deferred revenues					78.4	33.1
Accrued liabilities					69.7	65.9
Total current liabilities					210.8	188.5
Long-term debt, less current portion					0.0	0.0
Due to affiliates					578.6	1,215.9
Other liabilities					75.5	48.6
Deferred income taxes - net					144.0	150.8
Shareholders' equity					6,972.5	6,396.2
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY					$ 7,981.4	$ 8,000.0
Condensed Consolidating Income Statements
REVENUES	378.5	543.5	1,488.0	1,600.0
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	191.3	259.4	627.0	796.0
Depreciation and amortization	96.7	97.2	286.5	273.6
Selling, general and administrative	19.2	27.3	61.7	75.7
Loss on disposals of property and equipment	0.7	1.8	4.7	1.6
Material charges and other operating items	32.9	332.3	32.9	337.3
Total costs and expenses	340.8	718.0	1,012.8	1,484.2
Income (loss) from operations	37.7	(174.5)	475.2	115.8
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	(0.6)	(14.0)	(3.7)	(20.5)
Interest income	0.8	0.5	1.6	0.8
Gain on extinguishment of debt			0.0
Other - net	(2.1)	(1.7)	(5.4)	(2.9)
Total other income (expense), net	(1.9)	(15.2)	(7.5)	(22.6)
INCOME (LOSS) BEFORE INCOME TAXES	35.8	(189.7)	467.7	93.2
Provision (benefit) for income taxes	(5.2)	(11.8)	17.3	30.5
Equity in earnings of subsidiaries, net of tax	0.0	0.0	0.0	0.0
NET INCOME (LOSS)	41.0	(177.9)	450.4	62.7
Statements of Comprehensive Income (Loss)
NET INCOME (LOSS)	41.0	(177.9)	450.4	62.7
OTHER COMPREHENSIVE INCOME:
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income taxes	0.0		0.0
Net reclassification adjustments for amount recognized in net income (loss) as a component of net periodic benefit cost, net of income taxes	0.0	0.0	0.0	0.0
OTHER COMPREHENSIVE INCOME	0.0		0.0
COMPREHENSIVE INCOME (LOSS)	41.0	(177.9)	450.4	62.7
Consolidating Statements of Cash Flows
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES			804.1	687.5
INVESTING ACTIVITIES:
Capital expenditures			(57.3)	(660.0)
Proceeds from disposals of property and equipment			0.7	2.3
Advances on subsidiary notes receivables				0.0
Collections on subsidiary notes receivables			0.0	0.0
Investments in consolidated subsidiaries			0.0	0.0
Net cash provided by (used in) investing activities			(56.6)	(657.7)
FINANCING ACTIVITIES:
Advances (to) from affiliates			(76.6)	(30.8)
Contributions from issuer			204.8	36.7
Proceeds from borrowings				481.3
Reductions of long-term debt			(580.8)	(441.2)
Dividends paid			(79.7)	(49.0)
Net cash provided by (used in) financing activities			(532.3)	(3.0)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			215.2	26.8
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			457.4	244.7
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 672.6	$ 271.5	$ 672.6	$ 271.5