Basis of Presentation and Significant Accounting Policies FX gain (loss) (Details) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Foreign Currency Transaction Gain (Loss), before Tax			$ 19,142	$ (26,741)
Loss and Loss Reserves [Member]
Foreign Currency Transaction Gain (Loss), before Tax			26,556	(56,910)
Gain (Loss) on Investments [Member]
Foreign Currency Transaction Gain (Loss), before Tax	$ (3,348)	$ 8,398	(3,780)	22,030
Premiums Receivable [Member]
Foreign Currency Transaction Gain (Loss), before Tax			(1,960)	8,264
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member]
Foreign Currency Transaction Gain (Loss), before Tax			$ (1,141)	$ (929)