Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investment securities:
Held-to-maturity, Estimated fair value	$ 584	$ 640
Shareholders’ equity:
Preferred stock, shares authorized (in shares)	4,400,000	4,400,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	163,800,000	164,090,000
Common stock, outstanding shares (in shares)	163,800,000	164,090,000