Derivative Instruments (Fair Values of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Assets:
Current	$ 248.3	$ 446.6
Long-term	1,710.5	1,314.8
Total	1,958.8	1,761.4
Liabilities:
Current	385.2	1,043.7
Long-term	1,871.5	1,517.1
Total	2,256.7	2,560.8
Cross-currency and interest rate derivative contracts
Assets:
Current	187.8	443.6
Long-term	1,428.9	913.7
Total	1,616.7	1,357.3
Liabilities:
Current	342.4	1,027.4
Long-term	1,639.5	1,443.9
Total	1,981.9	2,471.3
Equity Contract [Member]
Assets:
Total	334.7	400.2
Liabilities:
Total	265.3	88.4
Foreign Exchange Forward [Member]
Assets:
Current	4.9	2.5
Long-term	0.0	0.0
Total	4.9	2.5
Liabilities:
Current	9.3	0.8
Long-term	0.0	0.0
Total	9.3	0.8
Other
Assets:
Total	2.5	1.4
Liabilities:
Total	0.2	0.3
Liberty Global Group [Member]
Assets:
Current	245.0	445.5
Long-term	1,521.1	1,213.6
Total	1,766.1	1,659.1
Liabilities:
Current	352.6	1,004.0
Long-term	1,868.5	1,517.1
Total	2,221.1	2,521.1
Liberty Global Group [Member] | Cross-currency and interest rate derivative contracts
Assets:
Current	187.8	443.6
Long-term	1,239.5	812.5
Total	1,427.3	1,256.1
Liabilities:
Current	309.8	987.9
Long-term	1,636.5	1,443.9
Total	1,946.3	2,431.8
Liberty Global Group [Member] | Equity Contract [Member]
Assets:
Current	54.1	0.0
Long-term	280.6	400.2
Total	334.7	400.2
Liabilities:
Current	33.4	15.3
Long-term	231.9	73.1
Total	265.3	88.4
Liberty Global Group [Member] | Foreign Exchange Forward [Member]
Assets:
Current	1.6	1.4
Long-term	0.0	0.0
Total	1.6	1.4
Liabilities:
Current	9.3	0.6
Long-term	0.0	0.0
Total	9.3	0.6
Liberty Global Group [Member] | Other
Assets:
Current	1.5	0.5
Long-term	1.0	0.9
Total	2.5	1.4
Liabilities:
Current	0.1	0.2
Long-term	0.1	0.1
Total	0.2	0.3
LiLAC Group [Member]
Assets:
Current	3.3	1.1
Long-term	189.4	101.2
Total	192.7	102.3
Liabilities:
Current	32.6	39.7
Long-term	3.0	0.0
Total	35.6	39.7
LiLAC Group [Member] | Cross-currency and interest rate derivative contracts
Assets:
Current	0.0	0.0
Long-term	189.4	101.2
Total	189.4	101.2
Liabilities:
Current	32.6	39.5
Long-term	3.0	0.0
Total	35.6	39.5
LiLAC Group [Member] | Foreign Exchange Forward [Member]
Assets:
Current	3.3	1.1
Long-term	0.0	0.0
Total	3.3	1.1
Liabilities:
Current	0.0	0.2
Long-term	0.0	0.0
Total	$ 0.0	$ 0.2