Derivative Financial Instruments - Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Realized losses reclassified from AOCI	$ 16	$ 11	$ 31	$ 16
Interest Rate Swap \| Designated as Hedging Instrument
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Realized losses reclassified from AOCI	$ 21	$ 16	$ 41	$ 21

Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=124509347&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=124509347&loc=d3e637-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration