Commitments and Contingencies Contract Settlement (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
contract settlement-ST	$ (1,667)	$ 12,700	$ 28,900	$ (2,083)