Share-Based Compensation (Share-Based Compensation Restricted Units) (Details) - Restricted Share Units [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units outstanding January 1, Number Of Restricted Share Units	717,696	799,129	696,641
Granted, Number Of Restricted Share Units	97,140	138,567	340,957
Vested, Number Of Restricted Share Units	(160,329)	(164,104)	(144,473)
Forfeited, Number Of Restricted Share Units	(35,357)	(55,896)	(93,996)
Restricted share units outstanding December 31, Number Of Restricted Share Units	619,150	717,696	799,129
Restricted share units outstanding January 1, Grant Date Aggregate Fair Value	$ 151,212	$ 166,144	$ 136,905
Granted, Grant Date Aggregate Fair Value	21,113	27,733	73,953
Vested, Grant Date Aggregate Fair Value	(32,714)	(30,717)	(25,305)
Forfeited, Grant Date Aggregate Fair Value	(7,553)	(11,948)	(19,409)
Restricted share units outstanding December 31, Grant Date Aggregate Fair Value	$ 132,058	$ 151,212	$ 166,144