Derivative Instruments (Fair Values of Derivative Assets and Liabilities) (Schedule and Footnotes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Current	$ 412.7	$ 421.9
Long-term	2,763.4	2,084.2
Total	3,176.1	2,506.1
Liability:
Current	281.2	346.3
Long-term	1,028.7	1,248.3
Total	1,309.9	1,594.6
Cross-currency and interest rate derivative contracts [Member]
Assets:
Current	344.4	275.4
Long-term	2,262.1	1,810.2
Total	2,606.5	2,085.6
Liability:
Current	263.7	304.9
Long-term	1,028.5	1,208.5
Total	1,292.2	1,513.4
Valuation adjustment in asset cross currency and interest rate derivative contracts	93.1	64.0
Valuation adjustment in liability cross currency and interest rate derivative contracts	71.5	86.5
Gain (loss) on change in credit risk valuation included in realized and unrealized gains (losses) on derivative instruments, net	(16.4)	(9.3)	$ (120.9)
Equity-related derivative instruments [Member]
Assets:
Total	524.0	408.5
Liability:
Total	8.6	74.4
Foreign currency forward contracts [Member]
Assets:
Current	31.0	10.4
Long-term	14.1	0.0
Total	45.1	10.4
Liability:
Current	8.9	1.1
Long-term	0.1	0.0
Total	9.0	1.1
Other Contract [Member]
Assets:
Total	0.5	1.6
Liability:
Total	0.1	5.7
Liberty Global Group [Member]
Assets:
Current	405.5	405.9
Long-term	2,624.4	1,792.5
Total	3,029.9	2,198.4
Liability:
Current	252.4	346.3
Long-term	999.8	1,234.5
Total	1,252.2	1,580.8
Liberty Global Group [Member] | Cross-currency and interest rate derivative contracts [Member]
Assets:
Current	337.5	263.6
Long-term	2,123.1	1,518.5
Total	2,460.6	1,782.1
Liability:
Current	239.1	304.9
Long-term	999.6	1,194.7
Total	1,238.7	1,499.6
Liberty Global Group [Member] | Equity-related derivative instruments [Member]
Assets:
Current	37.1	135.5
Long-term	486.9	273.0
Total	524.0	408.5
Liability:
Current	8.6	34.7
Long-term	0.0	39.7
Total	8.6	74.4
Liberty Global Group [Member] | Foreign currency forward contracts [Member]
Assets:
Current	30.7	6.2
Long-term	14.1	0.0
Total	44.8	6.2
Liability:
Current	4.7	1.1
Long-term	0.1	0.0
Total	4.8	1.1
Liberty Global Group [Member] | Other Contract [Member]
Assets:
Current	0.2	0.6
Long-term	0.3	1.0
Total	0.5	1.6
Liability:
Current	0.0	5.6
Long-term	0.1	0.1
Total	0.1	5.7
LiLAC Group [Member]
Assets:
Current	7.2	16.0
Long-term	139.0	291.7
Total	146.2	307.7
Liability:
Current	28.8	0.0
Long-term	28.9	13.8
Total	57.7	13.8
LiLAC Group [Member] | Cross-currency and interest rate derivative contracts [Member]
Assets:
Current	6.9	11.8
Long-term	139.0	291.7
Total	145.9	303.5
Liability:
Current	24.6	0.0
Long-term	28.9	13.8
Total	53.5	13.8
LiLAC Group [Member] | Foreign currency forward contracts [Member]
Assets:
Current	0.3	4.2
Long-term	0.0	0.0
Total	0.3	4.2
Liability:
Current	4.2	0.0
Long-term	0.0	0.0
Total	$ 4.2	$ 0.0