Stock-Based Compensation (Summary Of The Status Of Nonvested Share Awards) (Details)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Nonvested Share Awards [Roll Forward]
Nonvested, Shares, Beginning Balance | shares	1,180,940
Granted, Shares | shares	178,446
Vested, Shares | shares	(291,519)
Forfeited, Shares | shares	(3,246)
Nonvested, Shares, Ending Balance | shares	1,064,621
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 43.24
Granted , Weighted Average Grant Date Fair Value | $ / shares	61.87
Vested , Weighted Average Grant Date Fair Value | $ / shares	32.68
Forfeited , Weighted Average Grant Date Fair Value | $ / shares	49.41
Nonvested , Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 49.23