New Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Mar. 31, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lease liabilities		$ 670,775
ASU 2017-08 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on retained earnings	$ 4,400
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on retained earnings	2,400
Right-of-use assets	$ 670,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Lease liabilities	$ 670,000
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent