CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2013	$ 19,196	$ 0	$ 6	$ 18,603	$ 1,235	$ 0	$ (648)
Beginning balance (in shares) at Dec. 31, 2013		0	560
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to RBS	(35)				(35)
Dividends to RBS — exchange transactions	(333)				(333)
Total comprehensive income:
Net income	479				479
Other comprehensive income	290						290
Total comprehensive income	769				479		290
Ending balance at Jun. 30, 2014	19,597	$ 0	$ 6	18,603	1,346	0	(358)
Ending balance (in shares) at Jun. 30, 2014		0	560
Beginning balance at Dec. 31, 2014	19,268	$ 0	$ 6	18,676	1,294	(336)	(372)
Beginning balance (in shares) at Dec. 31, 2014		0	546
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(48)				(48)
Dividends to RBS	(60)				(60)
Issuance of preferred stock (in shares)		0
Issuance of preferred stock	247	$ 247
Treasury stock purchased (in shares)			(10)
Treasury stock purchased	(250)					(250)
Share-based compensation plans (in shares)			1
Share-based compensation plans	13			34		(21)
Employee stock purchase plan shares issued	4			4
Total comprehensive income:
Net income	399				399
Other comprehensive income	13						13
Total comprehensive income	412				399		13
Ending balance at Jun. 30, 2015	$ 19,586	$ 247	$ 6	$ 18,714	$ 1,585	$ (607)	$ (359)
Ending balance (in shares) at Jun. 30, 2015		0	537