Supplemental Guarantor Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Condensed Consolidating Balance Sheets
Cash and cash equivalents	$ 8.5	$ 7.4	$ 25.4	$ 57.9
Restricted Cash and Cash Equivalents	90.7
Other current assets	4.2	2.2
Total current assets	313.6	200.4
Property, plant and equipment, net	1,052.6	975.5
Investment in CyrusOne	21.0	55.5
Goodwill	14.3	14.3
Other noncurrent assets	19.7	17.8
Total assets	1,529.9	1,446.4
Current portion of long-term debt	98.8	13.8
Accounts payable	134.3	128.9
Other current liabilities	25.3	25.0
Other current liabilities from discontinued operations	0.4	5.4
Total current liabilities	354.3	259.2
Long-term debt, less current portion	1,125.5	1,223.8
Other noncurrent liabilities	30.9	36.6
Total liabilities	1,724.7	1,744.6
Shareowners' (deficit) equity	(194.8)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,529.9	1,446.4
Notes guaranteed by parent [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	8.5	7.4	25.4	57.9
Restricted Cash and Cash Equivalents	90.7
Receivables, net	172.2	157.1
Other current assets	42.2	35.9
Total current assets	313.6	200.4
Property, plant and equipment, net	1,052.6	975.5
Investment in CyrusOne	21.0	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	128.4	200.7
Total assets	1,529.9	1,446.4
Current portion of long-term debt	98.8	13.8
Accounts payable	134.3	128.9
Other current liabilities	120.8	111.1
Other current liabilities from discontinued operations	0.4	5.4
Total current liabilities	354.3	259.2
Long-term debt, less current portion	1,125.5	1,223.8
Other noncurrent liabilities	244.9	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,724.7	1,744.6
Shareowners' (deficit) equity	(194.8)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,529.9	1,446.4
Notes guaranteed by parent [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.0	0.0	0.0	0.0
Restricted Cash and Cash Equivalents	0.0
Receivables, net	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	(1,674.7)	(1,555.7)
Other noncurrent assets	(140.3)	(146.3)
Total assets	(1,815.0)	(1,702.0)
Current portion of long-term debt	0.0	0.0
Accounts payable	0.0	0.0
Other current liabilities	0.0	0.0
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	0.0	0.0
Long-term debt, less current portion	0.0	0.0
Other noncurrent liabilities	(140.3)	(146.2)
Intercompany payables	(2.7)	(54.7)
Total liabilities	(143.0)	(200.9)
Shareowners' (deficit) equity	(1,672.0)	(1,501.1)
Total liabilities and shareowners' equity (deficit)	(1,815.0)	(1,702.0)
Notes guaranteed by parent [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	6.8	4.6	22.1	56.2
Restricted Cash and Cash Equivalents	90.7
Receivables, net	14.6	0.7
Other current assets	1.8	1.6
Total current assets	113.9	6.9
Property, plant and equipment, net	0.4	0.3
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	815.1	844.6
Other noncurrent assets	181.4	207.2
Total assets	1,110.8	1,059.0
Current portion of long-term debt	90.0	5.4
Accounts payable	0.0	0.7
Other current liabilities	37.7	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	127.7	47.7
Long-term debt, less current portion	951.9	1,018.6
Other noncurrent liabilities	225.2	235.5
Intercompany payables	0.0	54.7
Total liabilities	1,304.8	1,356.5
Shareowners' (deficit) equity	(194.0)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,110.8	1,059.0
Notes guaranteed by parent [Member] | Cincinnati Bell Telephone Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	1.0	1.0	1.5	1.0
Restricted Cash and Cash Equivalents	0.0
Receivables, net	0.5	0.0
Other current assets	22.6	20.2
Total current assets	24.1	21.2
Property, plant and equipment, net	998.2	921.5
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	0.0	63.9
Other noncurrent assets	1.9	3.0
Total assets	1,026.4	1,011.8
Current portion of long-term debt	6.0	5.0
Accounts payable	87.4	84.8
Other current liabilities	56.2	45.3
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	149.6	135.1
Long-term debt, less current portion	98.6	134.3
Other noncurrent liabilities	159.1	168.3
Intercompany payables	2.7	0.0
Total liabilities	410.0	437.7
Shareowners' (deficit) equity	616.4	574.1
Total liabilities and shareowners' equity (deficit)	1,026.4	1,011.8
Notes guaranteed by parent [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.7	1.8	1.8	0.7
Restricted Cash and Cash Equivalents	0.0
Receivables, net	157.1	156.4
Other current assets	17.8	14.1
Total current assets	175.6	172.3
Property, plant and equipment, net	54.0	53.7
Investment in CyrusOne	21.0	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	859.6	647.2
Other noncurrent assets	85.4	136.8
Total assets	1,207.7	1,077.6
Current portion of long-term debt	2.8	3.4
Accounts payable	46.9	43.4
Other current liabilities	26.9	24.2
Other current liabilities from discontinued operations	0.4	5.4
Total current liabilities	77.0	76.4
Long-term debt, less current portion	75.0	70.9
Other noncurrent liabilities	0.9	4.0
Intercompany payables	0.0	0.0
Total liabilities	152.9	151.3
Shareowners' (deficit) equity	1,054.8	926.3
Total liabilities and shareowners' equity (deficit)	1,207.7	1,077.6
Notes guaranteed by subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	8.5	7.4	25.4	57.9
Restricted Cash and Cash Equivalents	90.7
Receivables, net	172.2	157.1
Other current assets	42.2	35.9
Total current assets	313.6	200.4
Property, plant and equipment, net	1,052.6	975.5
Investment in CyrusOne	21.0	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	128.4	200.7
Total assets	1,529.9	1,446.4
Current portion of long-term debt	98.8	13.8
Accounts payable	134.3	128.9
Other current liabilities	120.8	111.1
Other current liabilities from discontinued operations	0.4	5.4
Total current liabilities	354.3	259.2
Long-term debt, less current portion	1,125.5	1,223.8
Other noncurrent liabilities	244.9	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,724.7	1,744.6
Shareowners' (deficit) equity	(194.8)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,529.9	1,446.4
Notes guaranteed by subsidiaries [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.0	0.0	0.0	0.0
Restricted Cash and Cash Equivalents	0.0
Receivables, net	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	(1,839.4)	(1,679.3)
Other noncurrent assets	(140.3)	(146.2)
Total assets	(1,979.7)	(1,825.5)
Current portion of long-term debt	0.0	0.0
Accounts payable	0.0	0.0
Other current liabilities	0.0	0.0
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	0.0	0.0
Long-term debt, less current portion	0.0	0.0
Other noncurrent liabilities	(140.3)	(146.2)
Intercompany payables	(154.7)	(182.0)
Total liabilities	(295.0)	(328.2)
Shareowners' (deficit) equity	(1,684.7)	(1,497.3)
Total liabilities and shareowners' equity (deficit)	(1,979.7)	(1,825.5)
Notes guaranteed by subsidiaries [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	6.8	4.6	22.1	56.2
Restricted Cash and Cash Equivalents	90.7
Receivables, net	14.6	0.7
Other current assets	1.8	1.6
Total current assets	113.9	6.9
Property, plant and equipment, net	0.4	0.3
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	815.1	844.6
Other noncurrent assets	181.4	207.2
Total assets	1,110.8	1,059.0
Current portion of long-term debt	90.0	5.4
Accounts payable	0.0	0.7
Other current liabilities	37.7	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	127.7	47.7
Long-term debt, less current portion	951.9	1,018.6
Other noncurrent liabilities	225.2	235.5
Intercompany payables	0.0	54.7
Total liabilities	1,304.8	1,356.5
Shareowners' (deficit) equity	(194.0)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,110.8	1,059.0
Notes guaranteed by subsidiaries [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.2	0.4	0.3	0.2
Restricted Cash and Cash Equivalents	0.0
Receivables, net	1.7	2.8
Other current assets	18.6	15.6
Total current assets	20.5	18.8
Property, plant and equipment, net	53.0	53.4
Investment in CyrusOne	21.0	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	1,024.3	830.4
Other noncurrent assets	82.5	133.4
Total assets	1,213.4	1,103.6
Current portion of long-term debt	2.8	3.4
Accounts payable	63.7	95.6
Other current liabilities	37.4	26.8
Other current liabilities from discontinued operations	0.4	5.4
Total current liabilities	104.3	131.2
Long-term debt, less current portion	51.5	53.3
Other noncurrent liabilities	5.4	11.8
Intercompany payables	0.0	0.0
Total liabilities	161.2	196.3
Shareowners' (deficit) equity	1,052.2	907.3
Total liabilities and shareowners' equity (deficit)	1,213.4	1,103.6
Notes guaranteed by subsidiaries [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	1.5	2.4	$ 3.0	$ 1.5
Restricted Cash and Cash Equivalents	0.0
Receivables, net	155.9	153.6
Other current assets	21.8	18.7
Total current assets	179.2	174.7
Property, plant and equipment, net	999.2	921.8
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	0.0	4.3
Other noncurrent assets	4.8	6.3
Total assets	1,185.4	1,109.3
Current portion of long-term debt	6.0	5.0
Accounts payable	70.6	32.6
Other current liabilities	45.7	42.7
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	122.3	80.3
Long-term debt, less current portion	122.1	151.9
Other noncurrent liabilities	154.6	160.5
Intercompany payables	154.7	127.3
Total liabilities	553.7	520.0
Shareowners' (deficit) equity	631.7	589.3
Total liabilities and shareowners' equity (deficit)	$ 1,185.4	$ 1,109.3