Long-lived Assets - Impairment Charges (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill		$ 181.9	$ 610.0
Property and equipment and other	$ 16.0	17.5	5.7
Total impairment charges		199.4	615.7	$ 677.9
Goodwill		4,906.4	5,133.3	5,673.6
Hurricanes
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				238.2
Property and equipment and other				73.0
Other indefinite-lived intangible assets				44.1
Other				4.7
Total impairment charges				355.3
Annual Impairment Analysis
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				317.9
Panama
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill	$ 182.0		608.0
Total impairment charges		182.0	608.0
Goodwill		794.0
C&W
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill		181.9	610.0
Property and equipment and other		17.2	5.0
Total impairment charges		199.1	615.0	458.0
Goodwill		4,110.8	4,325.6	4,962.5
C&W | Hurricanes
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				117.3
Property and equipment and other				22.8
Other indefinite-lived intangible assets				0.0
Other				0.0
Total impairment charges				140.1
C&W | Annual Impairment Analysis
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				317.9
VTR/Cabletica
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill		0.0	0.0
Property and equipment and other		0.3	0.3
Total impairment charges		0.3	0.3	4.7
Goodwill		517.9	530.0	433.4
VTR/Cabletica | Hurricanes
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				0.0
Property and equipment and other				0.0
Other indefinite-lived intangible assets				0.0
Other				4.7
Total impairment charges				0.0
VTR/Cabletica | Annual Impairment Analysis
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				0.0
Liberty Puerto Rico
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill		0.0	0.0
Property and equipment and other		0.0	0.4
Total impairment charges		0.0	0.4	215.2
Goodwill		$ 277.7	$ 277.7	277.7
Liberty Puerto Rico | Hurricanes
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				120.9
Property and equipment and other				50.2
Other indefinite-lived intangible assets				44.1
Other				0.0
Total impairment charges				215.2
Liberty Puerto Rico | Annual Impairment Analysis
Schedule of Impairment Charges of Long-Lived Assets [Line Items]
Goodwill				$ 0.0