Basis of Presentation and Significant Accounting Policies FX gain (loss) (Details) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Foreign Currency Transaction Gain (Loss), before Tax	$ 5,018	$ 6,465
Loss and Loss Reserves [Member]
Foreign Currency Transaction Gain (Loss), before Tax	11,016	5,827
Gain (Loss) on Investments [Member]
Foreign Currency Transaction Gain (Loss), before Tax	(4,804)	1,916
Premiums Receivable [Member]
Foreign Currency Transaction Gain (Loss), before Tax	(1,387)	(560)
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member]
Foreign Currency Transaction Gain (Loss), before Tax	$ (25)	$ (706)