Loans Payable And Other Financial Liabilities (Carrying Amounts of Liability and Equity Components) (Details) - Convertible Senior Notes [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Aug. 31, 2018	Jun. 30, 2014
2028 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Amount of the equity component	$ 327,305,000	$ 327,305,000
Convertible senior notes	880,000,000	880,000,000	$ 880,000,000
Unamortized debt discount	(301,227,000)	(325,783,000)
Unamortized transaction costs related to the debt component	(9,468,000)	(9,958,000)
Contractual coupon interest accrual	23,809,000	5,867,000
Contractual coupon interest payment	(17,160,000)
Net carrying amount	$ 575,954,000	$ 550,126,000
Convertible senior notes, interest rate	2.00%	2.00%	2.00%
Transaction Costs Allocated Between Liability And Equity Components	$ 6,163,000
Remaining period over which the unamortized debt discount will be amortized	8 years 8 months 12 days
2019 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Amount of the equity component		$ 9,196,000
Convertible senior notes		65,987,000		$ 330,000,000
Unamortized debt discount		(1,063,000)
Unamortized transaction costs related to the debt component		(176,000)
Contractual coupon interest accrual		5,447,000
Contractual coupon interest payment		(5,447,000)
Net carrying amount		$ 64,748,000
Convertible senior notes, interest rate		2.25%		2.25%
Transaction Costs Allocated Between Liability And Equity Components	$ 236,000	$ 236,000