Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	[1]
Recent Accounting Pronouncements
Operating lease, right-of-use assets	$ 1,886,364	$ 0
Operating lease, liability	1,925,916
ASU 2016-02 [Member]
Recent Accounting Pronouncements
Cumulative effect adjustment to opening Retained earnings	1,400
Operating lease, right-of-use assets	1,900,000
Operating lease, liability	$ 1,900,000

[1] The balance sheet at December 31, 2018, has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by United States generally accepted accounting principles for complete financial statements.