Acquisitions and Strategic Transaction Expenses Tangent (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Bargain Purchase Gain	$ 70,890	$ 1,456	$ 0
Tangent [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		2,600
Bargain Purchase Gain		$ 1,500