Organization, Basis of Presentation and Recent Accounting Pronouncements (Recent Accounting Pronouncements) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease Right-of-Use Assets	$ 382,050	$ 369,333	$ 0
Total lease liabilities	$ 420,077
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease Right-of-Use Assets		369,333
Total lease liabilities		$ 418,300