Share-Based Compensation (Summary Of Changes In Nonvested Stock Units) (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Restricted Stock Units (RSUs)
Shares [Roll Forward]
Nonvested at beginning of period (in shares) | shares	1,722,300
Granted (in shares) | shares	1,516,000
Vested (in shares) | shares	(165,400)
Cancelled/forfeited (in shares) | shares	(95,500)
Nonvested at period end (in shares) | shares	2,977,400
Weighted-Average Grant Date Fair Value [Roll Forward]
Granted, weighted-average grant date fair value, beginning of period (in dollars per share) | $ / shares	$ 28.53
Granted, weighted-average grant date fair value (in dollars per share) | $ / shares	31.57
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	28.94
Cancelled/forfeited, weighted-average grant date fair value (in dollars per share) | $ / shares	27.85
Granted, weighted-average grant date fair value, period end ( in dollars per share) | $ / shares	$ 30.10
Performance Share Units
Shares [Roll Forward]
Nonvested at beginning of period (in shares) | shares	2,748,800
Granted (in shares) | shares	623,000
Vested (in shares) | shares	(203,600)
Cancelled/forfeited (in shares) | shares	(124,400)
Nonvested at period end (in shares) | shares	3,043,800
Weighted-Average Grant Date Fair Value [Roll Forward]
Granted, weighted-average grant date fair value, beginning of period (in dollars per share) | $ / shares	$ 25.59
Granted, weighted-average grant date fair value (in dollars per share) | $ / shares	36.06
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	34.55
Cancelled/forfeited, weighted-average grant date fair value (in dollars per share) | $ / shares	28.45
Granted, weighted-average grant date fair value, period end ( in dollars per share) | $ / shares	$ 27.02