Basis of Presentation (Effect of the Adoption of ASC Topic 842 Leases) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Assets and Liabilities [Line Items]
Operating Lease, Liability	$ 54,126	$ 55,800
Operating Lease, Right-of-Use Asset	$ 37,913	39,100	$ 0
Pre-Existing Lease Liability [Member]
Lease Assets and Liabilities [Line Items]
Operating Lease, Liability		$ 16,700