Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful receivables	$ 106	$ 117
Investments carried at fair value	1,699	1,512
Other intangible assets, accumulated amortization	$ 5,762	$ 5,161
Common stock authorized (in shares)	100.0000	100.0000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (in shares)	100	100
Treasury stock (in shares)	0	0
Primary Beneficiary | Cash and Cash Equivalents
Pledged current assets	$ 82	$ 107
Primary Beneficiary | Property, Plant and Equipment
Pledged noncurrent assets	734	907
Primary Beneficiary | Long-term Debt
Noncurrent liabilities - nonrecourse	$ 75	$ 249