Income Taxes Income Taxes - Effect of Income Taxes on Net Income and Stockholders' Equity (Details) - Successor [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit) [Roll Forward]
Income tax expense (benefit)	$ 44,464	$ 30,709	$ 17,364
Net Unrealized Losses On Securities Tax Effect	(30,838)	41,602	(55,906)
Valuation Allowances And Reserves Charged To Equity	4,616	13,647	(71,774)
Income Tax Effects Allocated Directly to Equity	44,464	30,709	17,364
Unrealized Loss on FX Tax Effect	25,776	(58,527)	(15,628)
Change in Retirement Benefits Tax Effect	$ 446	$ 3,278	$ (240)