Accounting Changes and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Assets:
Trade receivables, net	$ 1,342.1	$ 1,404.5		$ 1,403.8
Current assets of discontinued operations	356.5	276.0		374.2
Other current assets	396.7	351.2		427.8
Investments and related note receivables	5,121.8	6,671.4		6,862.6
Deferred tax assets	2,488.2	3,133.1		3,117.1
Long-term assets of discontinued operations	10,174.6	11,237.4		11,266.5
Other assets, net	3,632.9	3,720.2		3,741.6
Liabilities:
Deferred revenue	847.1	936.6		942.2
Current liabilities of discontinued operations	1,967.5	1,635.9		1,662.6
Other accrued and current liabilities	2,458.8	2,219.0		2,220.2
Long-term liabilities of discontinued operations	10,072.4	10,014.4		10,053.5
Other long-term liabilities	2,436.8	2,246.6		2,249.3
Equity:
Accumulated deficit	(5,172.2)	(6,217.6)		(5,897.5)
Noncontrolling interests	(533.1)	(412.0)		(407.6)
Other income, net	$ 43.4	46.4	$ 124.0
Accounting change		324.5	15.3
Accumulated deficit
Equity:
Accounting change		320.1	15.3
Accounting Standards Update 2017-07
Equity:
Other income, net		$ 18.2	$ 14.7
ASU 2014-09 Adjustments | Accounting Standards Update 2014-09
Assets:
Trade receivables, net				(0.7)
Current assets of discontinued operations				98.2
Other current assets				76.6
Investments and related note receivables				191.2
Deferred tax assets				(16.0)
Long-term assets of discontinued operations				29.1
Other assets, net				21.4
Liabilities:
Deferred revenue				5.6
Current liabilities of discontinued operations				26.7
Other accrued and current liabilities				1.2
Long-term liabilities of discontinued operations				39.1
Other long-term liabilities				2.7
Equity:
Accumulated deficit				320.1
Noncontrolling interests				$ 4.4