Stock-Based Compensation (Summary of Deferred Stock Awards to Non-Employee Directors) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Deferred awards outstanding, beginning of year	132,699
Shares diversified	0
Shares issued upon retirement	(67,020)
Deferred awards outstanding, end of year	65,679
Diversified Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Deferred awards outstanding, beginning of year	12,250
Shares diversified	13,348
Shares issued upon retirement	(20,000)
Deferred awards outstanding, end of year	5,598
Undiversified Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Deferred awards outstanding, beginning of year	120,449
Shares diversified	(13,348)
Shares issued upon retirement	(47,020)
Deferred awards outstanding, end of year	60,081