Derivative Financial Instruments - Narrative (Details)	9 Months Ended
	Sep. 30, 2023 USD ($) counterparty	Dec. 31, 2022 USD ($)
Derivative [Line Items]
Number of central counterparties | counterparty	2
Notional value	$ 1,931,320,000	$ 2,842,846,000
Derivative, fair value, amount offset against collateral, net	11,000,000	12,000,000
Estimated accumulated other comprehensive income to be reclassified in next 12 months	46,000,000
Cash collateral held relative to derivative exposure	0	0
Cash collateral pledged	11,000,000	$ 11,000,000
CME
Derivative [Line Items]
Notional value	$ 1,800,000,000
Percent of total notional derivative contracts	91.70%
Amount of variation margin included as settlement	$ (50,000,000)
LCH
Derivative [Line Items]
Notional value	$ 100,000,000
Percent of total notional derivative contracts	8.30%
Amount of variation margin included as settlement	$ (6,000,000)