Long-Term Debt and Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Common stock, outstanding shares (in shares)	147,684		148,153
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001
Common stock and additional paid in capital	$ 1,713		$ 1,731
Accumulated other comprehensive loss	6,025	$ 5,829	5,691	$ 5,283	$ 5,184	$ 4,893
Transfer in accumulated unrecognized loss	2,000		2,100
Unrealized loss, after tax	1,500		1,500
Net unrealized gains/(losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (2,432)		$ (2,526)	$ (2,706)		$ (2,800)