Income Taxes (Components of income tax expense (benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ComponentsOfIncomeTaxExpenseBenefitContinuingOperationsAbstract
Current Income Tax Expense Benefit	$ 19,101	$ 2,768	$ 19,775
Deferred Income Tax Expense (Benefit)	(3,658)	23,226	(37,329)
Income Tax Expense (Benefit)	$ 15,443	$ 25,994	$ (17,554)