CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Changes in unrealized gains (losses) - taxes (benefits)	$ 0	$ 35	$ 12	$ 49
Reclassification adjustment for net losses (gains) realized in net income - benefits (taxes)	(7)	(3)	(13)	(6)
Changes in market value of derivatives - taxes (benefits)	(2)	1	1	0
Reclassification adjustment for net losses (gains) realized in net income - benefits (taxes)	$ 2	$ 0	$ 2	$ 0