Income Taxes Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 1,379	$ 0
Effect of change in U.S. tax law	58,558	$ 0	$ 0
Deferred tax assets and liabilities before valuation allowance	76,444
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	4,584
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 81