Debt (Term Loan under the Senior Credit Agreement) (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 12,028,000,000	$ 12,028,000,000	$ 11,180,000,000
2018 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	2,328,000,000	2,328,000,000	$ 2,340,000,000
Repayment of term loans	$ 6,000,000.0	$ 12,000,000.0

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant