Derivative Instruments (Fair Values of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets:
Current	$ 369.0	$ 494.4
Long-term	1,864.8	1,633.3
September 30, 2018	2,233.8	2,127.7
Liabilities:
Current	293.8	223.3
Long-term	1,129.4	1,557.9
Total	1,423.2	1,781.2
Cross-currency and interest rate derivative contracts
Assets:
Current	353.5	477.0
Long-term	1,303.7	1,071.9
September 30, 2018	1,657.2	1,548.9
Liabilities:
Current	291.4	210.2
Long-term	1,129.3	1,557.7
Total	1,420.7	1,767.9
Equity-related derivative instruments:
Assets:
Current	7.5	0.0
Long-term	561.0	560.9
September 30, 2018	568.5	560.9
Liabilities:
Current	1.6	5.4
Long-term	0.0	0.0
Total	1.6	5.4
Foreign currency forward and option contracts
Assets:
Current	7.5	17.0
Long-term	0.1	0.1
September 30, 2018	7.6	17.1
Liabilities:
Current	0.8	7.7
Long-term	0.0	0.2
Total	0.8	7.9
Other
Assets:
Current	0.5	0.4
Long-term	0.0	0.4
September 30, 2018	0.5	0.8
Liabilities:
Current	0.0	0.0
Long-term	0.1	0.0
Total	$ 0.1	$ 0.0