Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation allowance, increase (decrease)	$ (21)	$ 21	$ (3,000)
Federal tax benefits	2,816	$ 227	$ (495)
Stock Compensation Plan [Member]
Operating Loss Carryforwards	237,000
U.S. Federal [Member]
Operating Loss Carryforwards	1,500,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	600,000
Foreign [Member]
Operating Loss Carryforwards	$ 53,200
Maximum [Member] | U.S. Federal [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Maximum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Maximum [Member] | Foreign [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2037
Minimum [Member] | U.S. Federal [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2024
Minimum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2018
Minimum [Member] | Foreign [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2022