Corporate Debt (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of Corporate Debt Instruments

Corporate debt at December 31, 2015 and 2014 is outlined in the following table (dollars in millions):

	Face Value		Discount			Net
December 31, 2015
Interest-bearing notes:
5 3/8% Notes, due 2022	$	540	$	(6	)	$	534
4 5/8% Notes, due 2023	460		(5		)	455
Total interest-bearing notes	1,000		(11		)	989
Non-interest-bearing debt:
0% Convertible debentures, due 2019	8		—			8
Total corporate debt	$	1,008	$	(11	)	$	997

	Face Value		Discount			Net
December 31, 2014
Interest-bearing notes:
6 3/8% Notes, due 2019	$	800	$	(5	)	$	795
5 3/8% Notes, due 2022	540		(7		)	533
Total interest-bearing notes	1,340		(12		)	1,328
Non-interest-bearing debt:
0% Convertible debentures, due 2019	38		—			38
Total corporate debt	$	1,378	$	(12	)	$	1,366

Schedule of Maturities of Corporate Debt [Table Text Block]

Scheduled principal payments of corporate debt at December 31, 2015 were as follows (dollars in millions):

Years ending December 31,
2016	$	—
2017	—
2018	—
2019	8
2020	—
Thereafter	1,000
Total future principal payments of corporate debt	1,008
Unamortized discount	(11		)
Total corporate debt	$	997