Derivative Instruments (Fair Values of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Assets:
Current	$ 359.7	$ 412.7
Long-term	2,498.2	2,763.4
Total	2,857.9	3,176.1
Liabilities:
Current	273.0	281.2
Long-term	900.3	1,028.7
Total	1,173.3	1,309.9
Cross-Currency and Interest Rate Derivative Contracts [Member]
Assets:
Current	260.2	344.4
Long-term	2,116.0	2,262.1
Total	2,376.2	2,606.5
Liabilities:
Current	249.1	263.7
Long-term	900.0	1,028.5
Total	1,149.1	1,292.2
Equity-Related Derivative Instruments [Member]
Assets:
Total	447.2	524.0
Liabilities:
Total	13.8	8.6
Foreign Exchange Contract [Member]
Assets:
Current	25.3	31.0
Long-term	8.3	14.1
Total	33.6	45.1
Liabilities:
Current	10.1	8.9
Long-term	0.3	0.1
Total	10.4	9.0
Other Contract [Member]
Assets:
Total	0.9	0.5
Liabilities:
Total		0.1
Liberty Global Group [Member]
Assets:
Current	350.0	405.5
Long-term	2,372.7	2,624.4
Total	2,722.7	3,029.9
Liabilities:
Current	237.0	252.4
Long-term	874.6	999.8
Total	1,111.6	1,252.2
Liberty Global Group [Member] | Cross-Currency and Interest Rate Derivative Contracts [Member]
Assets:
Current	251.1	337.5
Long-term	1,990.5	2,123.1
Total	2,241.6	2,460.6
Liabilities:
Current	217.2	239.1
Long-term	874.3	999.6
Total	1,091.5	1,238.7
Liberty Global Group [Member] | Equity-Related Derivative Instruments [Member]
Assets:
Current	73.8	37.1
Long-term	373.4	486.9
Total	447.2	524.0
Liabilities:
Current	13.8	8.6
Long-term	0.0	0.0
Total	13.8	8.6
Liberty Global Group [Member] | Foreign Exchange Contract [Member]
Assets:
Current	24.7	30.7
Long-term	8.3	14.1
Total	33.0	44.8
Liabilities:
Current	6.0	4.7
Long-term	0.3	0.1
Total	6.3	4.8
Liberty Global Group [Member] | Other Contract [Member]
Assets:
Current	0.4	0.2
Long-term	0.5	0.3
Total	0.9	0.5
Liabilities:
Current	0.0	0.0
Long-term	0.0	0.1
Total	0.0	0.1
LiLAC Group [Member]
Assets:
Current	9.7	7.2
Long-term	125.5	139.0
Total	135.2	146.2
Liabilities:
Current	36.0	28.8
Long-term	25.7	28.9
Total	61.7	57.7
LiLAC Group [Member] | Cross-Currency and Interest Rate Derivative Contracts [Member]
Assets:
Current	9.1	6.9
Long-term	125.5	139.0
Total	134.6	145.9
Liabilities:
Current	31.9	24.6
Long-term	25.7	28.9
Total	57.6	53.5
LiLAC Group [Member] | Foreign Exchange Contract [Member]
Assets:
Current	0.6	0.3
Long-term	0.0	0.0
Total	0.6	0.3
Liabilities:
Current	4.1	4.2
Long-term	0.0	0.0
Total	$ 4.1	$ 4.2