Accounting Changes and Error Corrections (Stockholders Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 8,063.0	$ 6,755.0	$ 8,063.0	$ 6,755.0	$ 7,081.0	$ 8,180.0	$ 7,805.0	$ 7,389.0
Stockholders' Equity Attributable to Noncontrolling Interest	90.0	90.0	90.0	90.0	90.0	0.0	90.0	90.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	8,153.0	6,845.0	8,153.0	6,845.0	7,171.0	8,180.0	7,895.0	7,479.0
Net income	287.0	(76.0)	744.0	226.0	517.0	1,170.0
Other Comprehensive Income (Loss), Net of Tax			538.0	(1,478.0)	(1,371.0)	409.0
Dividends, Common Stock, Cash	(56.0)	(54.0)	(163.0)	(152.0)	(205.0)	(194.0)
Treasury Stock, Value, Acquired, Cost Method	(50.0)	(27.0)	(169.0)	(54.0)	(81.0)	(99.0)
Stock Issued During Period, Value, Treasury Stock Reissued	(12.0)	(17.0)	(32.0)	(33.0)	(41.0)	(55.0)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(2.0)	(1.0)	(5.0)	(2.0)	(4.0)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	289.0	(75.0)	749.0	228.0	521.0
Net Income (Loss) Attributable to Noncontrolling Interest	$ 2.0	$ 1.0	$ 5.0	$ 2.0	4.0
Common Stock, Dividends, Per Share, Declared	$ 0.85	$ 0.80	$ 2.45	$ 2.26
Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					7,081.0	8,180.0			$ 6,839.0
Stockholders' Equity Attributable to Noncontrolling Interest					90.0	0.0			0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					7,171.0	8,180.0			6,839.0
Net income					517.0	1,170.0
Other Comprehensive Income (Loss), Net of Tax					(1,371.0)	409.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					521.0	1,170.0
Net Income (Loss) Attributable to Noncontrolling Interest					$ 4.0	$ 0.0
Common Stock, Dividends, Per Share, Declared					$ 3.06	$ 2.86
Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					$ 4,145.0	$ 13,014.0			14,352.0
Stockholders' Equity Attributable to Noncontrolling Interest					90.0	0.0			0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					4,235.0	13,014.0			14,352.0
Net income					623.0	617.0
Other Comprehensive Income (Loss), Net of Tax					(9,247.0)	(1,717.0)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					627.0	617.0
Net Income (Loss) Attributable to Noncontrolling Interest					4.0	0.0
Effect of Modified Retrospective Application Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(7,491.0)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest									(7,491.0)
Effect of Retrospective Application of Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(22.0)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest									(22.0)
Common Stock [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 1.0	$ 1.0	$ 1.0	$ 1.0	1.0	1.0	1.0	1.0
Common Stock [Member] | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					1.0	1.0			1.0
Common Stock [Member] | Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									1.0
Additional Paid-in Capital [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	2,534.0	2,493.0	2,534.0	2,493.0	2,502.0	2,461.0	2,522.0	2,478.0
Stock Issued During Period, Value, Treasury Stock Reissued	(12.0)	(15.0)	(32.0)	(32.0)	(41.0)	(55.0)
Additional Paid-in Capital [Member] | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					2,502.0	2,461.0			2,406.0
Additional Paid-in Capital [Member] | Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									2,406.0
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	8,713.0	7,936.0	8,713.0	7,936.0	8,169.0	7,871.0	8,483.0	8,067.0
Dividends, Common Stock, Cash	(56.0)	(54.0)	(163.0)	(152.0)	(205.0)	(194.0)
Stock Issued During Period, Value, Treasury Stock Reissued	(1.0)	(1.0)	(37.0)	(9.0)	(14.0)	(8.0)
Retained Earnings [Member] | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					8,169.0	7,871.0			6,903.0
Retained Earnings [Member] | Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									8,148.0
Retained Earnings [Member] | Effect of Modified Retrospective Application Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(1,187.0)
Retained Earnings [Member] | Effect of Retrospective Application of Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(58.0)
Treasury Stock, Common
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	(1,852.0)	(1,697.0)	(1,852.0)	(1,697.0)	(1,720.0)	(1,653.0)	(1,803.0)	(1,673.0)
Treasury Stock, Value, Acquired, Cost Method	50.0	27.0	169.0	54.0	81.0	99.0
Stock Issued During Period, Value, Treasury Stock Reissued	(1.0)	(3.0)	(37.0)	(10.0)	(14.0)	(8.0)
Treasury Stock, Common | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					(1,720.0)	(1,653.0)			(1,562.0)
Treasury Stock, Common | Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(1,562.0)
AOCI Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	(1,333.0)	(1,978.0)	(1,333.0)	$ (1,978.0)	(1,871.0)	(500.0)	$ (1,398.0)	$ (1,484.0)
Other Comprehensive Income (Loss), Net of Tax	$ 65.0	$ (494.0)	$ 538.0		(1,371.0)	409.0
AOCI Attributable to Parent [Member] | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent					$ (1,871.0)	$ (500.0)			(909.0)
AOCI Attributable to Parent [Member] | Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									5,359.0
AOCI Attributable to Parent [Member] | Effect of Modified Retrospective Application Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									(6,304.0)
AOCI Attributable to Parent [Member] | Effect of Retrospective Application of Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent									$ 36.0