Share Based Compensation (Summmary of Restricted Stock Unit Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Units Outstanding	1,294,070	1,400,699	1,709,813	2,047,158
Weighted Average Grant Price of Restricted Stock Units	$ 43.59	$ 37.65	$ 30.08	$ 25.08
Restricted Stock Units Granted	536,489	461,305	587,396
Weighted Average Grant Price of Restricted Stock Units Granted	$ 47.85	$ 53.17	$ 41.78
Restricted Stock Units Vested	(614,968)	(699,920)	(803,492)
Restricted Stock Units Forfeited	(28,150)	(70,499)	(121,249)
Weighted Average Grant Price of Restricted Stock Units Vested	$ 33.74	$ 29.56	$ 26.19
Weighted Average Grant Price of Restricted Stock Forfeited	$ 44.69	$ 35.95	$ 28.12