Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Debt outstanding [Table Text Block]

Debt outstanding was as follows:

(at December 31, in millions)	2019			2018
Short-term:
Commercial paper	$	100		$	100
3.90% Senior notes due November 1, 2020	500			—
5.90% Senior notes due June 2, 2019	—			500
Total short-term debt	600			600
Long-term:
3.90% Senior notes due November 1, 2020	—			500
7.75% Senior notes due April 15, 2026	200			200
7.625% Junior subordinated debentures due December 15, 2027	125			125
6.375% Senior notes due March 15, 2033	500			500
6.75% Senior notes due June 20, 2036	400			400
6.25% Senior notes due June 15, 2037	800			800
5.35% Senior notes due November 1, 2040	750			750
4.60% Senior notes due August 1, 2043	500			500
4.30% Senior notes due August 25, 2045	400			400
8.50% Junior subordinated debentures due December 15, 2045	56			56
3.75% Senior notes due May 15, 2046	500			500
8.312% Junior subordinated debentures due July 1, 2046	73			73
4.00% Senior notes due May 30, 2047	700			700
4.05% Senior notes due March 7, 2048	500			500
4.10% Senior notes due March 4, 2049	500			—
Total long-term debt	6,004			6,004
Total debt principal	6,604			6,604
Unamortized fair value adjustment	43			44
Unamortized debt issuance costs	(89		)	(84		)
Total debt	$	6,558		$	6,564

Merger-related unamortized fair value adjustments and the related effective interest rate [Table Text Block]

The following table presents merger-related unamortized fair value adjustments and the related effective interest rate:

				Unamortized Fair Value Purchase Adjustment at December 31,				Effective Interest Rate to Maturity
(in millions)	Issue Rate		Maturity Date	2019		2018
Junior subordinated debentures	7.625	%	Dec. 2027	$	11	$	12	6.147	%
	8.500	%	Dec. 2045	14		14		6.362	%
	8.312	%	Jul. 2046	18		18		6.362	%
Total				$	43	$	44