Common Stockholders' Equity (Schedule of Changes in Shares of Common Stock Outstanding) (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common Stock Shares Outstanding [Roll Forward]
Balance, beginning of year	177,825,150	183,411,907	182,993,640
Shares issued	708,057	776,544	687,339
Shares repurchased	(1,752,619)	(6,363,301)	(269,072)
Balance, end of year	176,780,588	177,825,150	183,411,907