Comprehensive Income - Schedule of Changes in Balances of Each Component of Accumulated Other Comprehensive Income (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Restated					$ (55,139)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					(2,900)
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ 99,476	$ (2,775)	$ (52,239)	$ (38,990)
Other comprehensive income before reclassifications	(6,280)	44,362	152,087	72,080
Amounts reclassified from accumulated other comprehensive income	(47,342)	(2,759)	(51,094)	5,738
Net current period other comprehensive income	(53,622)	41,603	100,993	77,818
Ending Balance	45,854	38,828	45,854	38,828
Income Tax Expense (Benefit)	1,995	6,882	4,600	26,463
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	153,059	140,198	30,755	118,863
Other comprehensive income before reclassifications	46,709	15,070	173,576	27,570
Amounts reclassified from accumulated other comprehensive income	(46,134)	(2,421)	(50,697)	6,414
Net current period other comprehensive income	575	12,649	122,879	33,984
Ending Balance	153,634	152,847	153,634	152,847
Accumulated Translation Adjustment [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(61,578)	(154,627)	(93,634)	(167,220)
Other comprehensive income before reclassifications	(52,989)	29,292	(20,933)	41,885
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net current period other comprehensive income	(52,989)	29,292	(20,933)	41,885
Ending Balance	(114,567)	(125,335)	(114,567)	(125,335)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ (2,900)
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(1,786)		(2,900)
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	(906)		208
Net current period other comprehensive income	(906)		208
Ending Balance	(2,692)		(2,692)
Other Postretirement Benefits Plan [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	9,781	11,654	10,640	9,367
Other comprehensive income before reclassifications	0	0	(556)	2,625
Amounts reclassified from accumulated other comprehensive income	(302)	(338)	(605)	(676)
Net current period other comprehensive income	(302)	(338)	(1,161)	1,949
Ending Balance	9,479	11,316	9,479	11,316
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Income Tax Expense (Benefit)	1,122	0	(586)	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Other Postretirement Benefits Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	(241)	(241)	(482)	(482)
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	(302)	(338)	(605)	(676)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	61	97	123	194
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(302)	(338)	(605)	(676)
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0	$ 0