Debt Short-term Debt (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Short-term Debt [Abstract]
Short-term debt	$ 100,500	$ 54,200	$ 0
Short-term Debt Maximum Remaining Maturity	12 days
Short-term Debt Average Remaining Maturity	7 days