Debt (tables)

12 Months Ended

Dec. 31, 2016

Debt disclosure

Debt outstanding [Table Text Block]

(at December 31, in millions)	2016			2015
Short-term:
Commercial paper	$	100		$	100
5.75% Senior notes due December 15, 2017	450			—
6.25% Senior notes due June 20, 2016	—			400
Total short-term debt	550			500
Long-term:
5.75% Senior notes due December 15, 2017	—			450
5.80% Senior notes due May 15, 2018	500			500
5.90% Senior notes due June 2, 2019	500			500
3.90% Senior notes due November 1, 2020	500			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 dues May 15, 2046	500			—
8.312% Junior subordinated debentures due July 1, 2046	73			73
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067	107			107
Total long-term debt	5,911			5,861
Total debt principal	6,461			6,361
Unamortized fair value adjustment	47			49
Unamortized debt issuance costs	(71		)	(66		)
Total debt	$	6,437		$	6,344

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

				Unamortized Fair Value Purchase Adjustment at December 31,				Effective Interest Rate
(in millions)	Issue Rate		Maturity Date	2016		2015		to Maturity
Subordinated debentures	7.625	%	Dec. 2027	$	14	$	15	6.147	%
	8.500	%	Dec. 2045	15		15		6.362	%
	8.312	%	Jul. 2046	18		19		6.362	%
Total				$	47	$	49