Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Held-to-maturity, fair value	$ 774	$ 850
Preferred stock, authorized shares	4,400,000	4,400,000
Common stock, authorized shares	350,000,000	350,000,000
Common stock, issued shares	202,131,000	203,085,000
Common stock, outstanding shares	202,131,000	203,085,000