Supplemental Guarantor Information CBT Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net	$ 285.3	$ 312.4	$ 299.2	$ 288.9	$ 289.3	$ 299.8	$ 285.8	$ 292.9	$ 1,185.8	$ 1,167.8	$ 1,161.5
Costs and Expenses									1,092.8	1,039.8	984.6
Operating Income (Loss)	10.5	25.5	27.4	29.6	25.0	36.2	29.7	37.1	93.0	128.0	176.9
Other Nonoperating Income (Expense)									7.6	(2.6)	(5.1)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									162.9	450.6	199.1
Income tax expense (benefit)									61.1	159.8	81.4
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(1.6)	18.8	77.6	7.0	30.5	79.3	180.7	0.3	101.8	290.8	117.7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0.3	0.0	0.0	0.0	2.1	1.0	10.9	48.9	0.3	62.9	(42.1)
Net Income (Loss) Attributable to Parent	$ (1.3)	$ 18.8	$ 77.6	$ 7.0	$ 32.6	$ 80.3	$ 191.6	$ 49.2	102.1	353.7	75.6
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									80.7	2.9	(40.6)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									182.8	356.6	35.0
Preferred Stock Dividends, Income Statement Impact									10.4	10.4	10.4
Net Income (Loss) Available to Common Stockholders, Basic									91.7	343.3	65.2
Notes guaranteed by parent [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net									1,185.8	1,167.8	1,161.5
Costs and Expenses									1,092.8	1,039.8	984.6
Operating Income (Loss)									93.0	128.0	176.9
Interest Income (Expense), Net									75.7	103.1	145.9
Other Nonoperating Income (Expense)									(145.6)	(425.7)	(168.1)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									162.9	450.6	199.1
Income tax expense (benefit)									61.1	159.8	81.4
Equity in earnings of subsidiaries, net of tax									0.0	0.0	0.0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									101.8	290.8	117.7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.3	62.9	(42.1)
Net Income (Loss) Attributable to Parent									102.1	353.7	75.6
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									80.7	2.9	(40.6)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									182.8	356.6	35.0
Preferred Stock Dividends, Income Statement Impact									10.4	10.4	10.4
Net Income (Loss) Available to Common Stockholders, Basic									91.7	343.3	65.2
Notes guaranteed by parent [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net									(39.8)	(38.6)	(39.1)
Costs and Expenses									(39.8)	(38.6)	(39.1)
Operating Income (Loss)									0.0	0.0	0.0
Interest Income (Expense), Net									0.0	0.0	0.0
Other Nonoperating Income (Expense)									0.0	0.0	0.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									0.0	0.0	0.0
Income tax expense (benefit)									0.0	0.0	0.0
Equity in earnings of subsidiaries, net of tax									(191.0)	(455.0)	(201.5)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									(191.0)	(455.0)	(201.5)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.0	0.0	0.0
Net Income (Loss) Attributable to Parent									(191.0)	(455.0)	(201.5)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									0.0	0.0	0.0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									(191.0)	(455.0)	(201.5)
Preferred Stock Dividends, Income Statement Impact									0.0	0.0	0.0
Net Income (Loss) Available to Common Stockholders, Basic									(191.0)	(455.0)	(201.5)
Notes guaranteed by parent [Member] | Parent Company [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net									0.0	0.0	0.0
Costs and Expenses									20.7	22.4	21.5
Operating Income (Loss)									(20.7)	(22.4)	(21.5)
Interest Income (Expense), Net									94.4	112.7	142.6
Other Nonoperating Income (Expense)									20.3	19.5	17.6
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									(135.4)	(154.6)	(181.7)
Income tax expense (benefit)									(46.5)	(53.3)	(55.8)
Equity in earnings of subsidiaries, net of tax									191.0	455.0	201.5
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									102.1	353.7	75.6
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.0	0.0	0.0
Net Income (Loss) Attributable to Parent									102.1	353.7	75.6
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									12.7	3.3	(40.5)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									114.8	357.0	35.1
Preferred Stock Dividends, Income Statement Impact									10.4	10.4	10.4
Net Income (Loss) Available to Common Stockholders, Basic									91.7	343.3	65.2
Notes guaranteed by parent [Member] | Cincinnati Bell Telephone Company [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net									677.8	660.1	659.6
Costs and Expenses									592.5	538.6	488.0
Operating Income (Loss)									85.3	121.5	171.6
Interest Income (Expense), Net									4.5	(0.9)	(4.5)
Other Nonoperating Income (Expense)									4.9	7.0	7.4
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									75.9	115.4	168.7
Income tax expense (benefit)									27.1	41.1	61.7
Equity in earnings of subsidiaries, net of tax									0.0	0.0	0.0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									48.8	74.3	107.0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.0	0.0	0.0
Net Income (Loss) Attributable to Parent									48.8	74.3	107.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									0.0	0.0	0.0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									48.8	74.3	107.0
Preferred Stock Dividends, Income Statement Impact									0.0	0.0	0.0
Net Income (Loss) Available to Common Stockholders, Basic									48.8	74.3	107.0
Notes guaranteed by parent [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)
Revenue, Net									547.8	546.3	541.0
Costs and Expenses									519.4	517.4	514.2
Operating Income (Loss)									28.4	28.9	26.8
Interest Income (Expense), Net									(23.2)	(8.7)	7.8
Other Nonoperating Income (Expense)									(170.8)	(452.2)	(193.1)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									222.4	489.8	212.1
Income tax expense (benefit)									80.5	172.0	75.5
Equity in earnings of subsidiaries, net of tax									0.0	0.0	0.0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									141.9	317.8	136.6
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.3	62.9	(42.1)
Net Income (Loss) Attributable to Parent									142.2	380.7	94.5
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									68.0	(0.4)	(0.1)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									210.2	380.3	94.4
Preferred Stock Dividends, Income Statement Impact									0.0	0.0	0.0
Net Income (Loss) Available to Common Stockholders, Basic									$ 142.2	$ 380.7	$ 94.5