CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at beginning of period at Dec. 31, 2013		$ 1,565
Balance at beginning of period at Dec. 31, 2013			$ 0	$ 14,106	$ 952	$ (159)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock redemption		0
Capital contribution from parent				0
Employee benefit plans				3
Net income	$ 284				284
Cash dividends declared on preferred stock					(55)
Other comprehensive income (loss), net of tax	187					187
Balance at end of period at Sep. 30, 2014	15,318		0	14,109	1,181	28
Balance at end of period at Sep. 30, 2014	16,883	1,565
Balance at beginning of period at Dec. 31, 2014	16,967	1,565
Balance at beginning of period at Dec. 31, 2014	15,402		0	14,170	1,233	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock redemption		(300)
Capital contribution from parent				4,000
Employee benefit plans				3
Net income	455				455
Cash dividends declared on preferred stock					(50)
Other comprehensive income (loss), net of tax	(255)					(255)
Balance at end of period at Sep. 30, 2015	19,555		$ 0	$ 18,173	$ 1,638	$ (256)
Balance at end of period at Sep. 30, 2015	$ 20,820	$ 1,265