Income Taxes Income Tax (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Valuation Allowance [Line Items]
Provision for income taxes	$ 5,620	$ 8,196	$ 11,430	$ 17,648
Effective Income Tax Rate Reconciliation, Percent	16.80%	32.50%	19.90%	34.30%
Corporate Federal Tax Rate				35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ 3,000