Income Taxes - Schedule of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Deferred tax assets, future policy benefit reserves and unpaid policy claims	$ 206,794	$ 223,845
Deferred tax assets, goodwill and intangible assets	19,436	36,261
Deferred tax assets, future deductible liabilities	10,235	19,831
Deferred tax assets, share-based compensation	7,288	15,592
Deferred tax assets, state income taxes	12,521	11,425
Deferred tax assets, foreign tax credits	40,386
Deferred tax assets, other	2,857	103
Total deferred tax assets before valuation allowance	299,517	307,057
Valuation allowance on foreign tax credits	(40,386)
Total deferred tax assets after valuation allowance	259,131	307,057
Deferred tax liabilities:
Deferred tax liabilities, deferred policy acquisition costs	(275,388)	(366,144)
Deferred tax liabilities, timing difference for haircut on deductibility of future policy benefit reserves prescribed in the Tax Reform Act	(22,307)
Deferred tax liabilities, investments	(9,884)	(16,769)
Deferred tax liabilities, unremitted earnings on foreign subsidiaries	(2,614)	(2,700)
Deferred tax liabilities, reinsurance deposit asset	(45,641)	(70,852)
Deferred tax liabilities, other	(7,255)	(11,864)
Total deferred tax liabilities	(363,089)	(468,329)
Net deferred tax liabilities	$ (103,958)	$ (161,272)