Derivative Instruments (Fair Values of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets:
Current	$ 374.2	$ 576.0
Long-term	1,795.7	1,733.0
Total	2,169.9	2,309.0
Liabilities:
Current	391.0	252.2
Long-term	1,967.1	1,866.6
Total	2,358.1	2,118.8
Cross-currency and interest rate derivative contracts [Member]
Assets:
Current	362.7	558.5
Long-term	1,089.9	1,171.4
Total	1,452.6	1,729.9
Liabilities:
Current	380.1	239.1
Long-term	1,967.1	1,866.4
Total	2,347.2	2,105.5
Equity-related derivative instruments [Member]
Assets:
Current	0.0	0.0
Long-term	705.3	560.9
Total	705.3	560.9
Liabilities:
Current	5.1	5.4
Long-term	0.0	0.0
Total	5.1	5.4
Foreign currency forward and option contracts [Member]
Assets:
Current	11.0	17.0
Long-term	0.0	0.1
Total	11.0	17.1
Liabilities:
Current	5.8	7.7
Long-term	0.0	0.2
Total	5.8	7.9
Other [Member]
Assets:
Current	0.5	0.5
Long-term	0.5	0.6
Total	$ 1.0	$ 1.1