Equity (OTTI Net Unrealized Investment Gains (Losses) in AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (314,948)
Ending Balance	(90,124)	$ (314,948)
OTTI | Net Unrealized Gains (Losses) on Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,261)	9	$ 1
Net investment gains (losses) on investments arising during the period	11,328	378	(9)
Reclassification adjustment for (gains) losses included in net income	2,172	556	17
Reclassification adjustment for OTTI losses excluded from net income	72	(2,204)	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	0	0	0
Impact of net unrealized investment (gains) losses on future policy benefits	0	0	0
Ending Balance	12,311	(1,261)	9
OTTI | Deferred Policy Acquisition Costs and Other Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,133)	(3)	0
Net investment gains (losses) on investments arising during the period	0	0	0
Reclassification adjustment for (gains) losses included in net income	0	0	0
Reclassification adjustment for OTTI losses excluded from net income	0	0	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	1,125	(2,130)	(3)
Impact of net unrealized investment (gains) losses on future policy benefits	0	0	0
Ending Balance	(1,008)	(2,133)	(3)
OTTI | Future Policy Benefits and Other Liabilities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(522)	0	0
Net investment gains (losses) on investments arising during the period	0	0	0
Reclassification adjustment for (gains) losses included in net income	0	0	0
Reclassification adjustment for OTTI losses excluded from net income	0	0	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	0	0	0
Impact of net unrealized investment (gains) losses on future policy benefits	365	(522)	0
Ending Balance	(157)	(522)	0
OTTI | Deferred Income Tax (Liability) Benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1,387	14	16
Net investment gains (losses) on investments arising during the period	(3,481)	(132)	3
Reclassification adjustment for (gains) losses included in net income	(667)	(195)	(6)
Reclassification adjustment for OTTI losses excluded from net income	(22)	771	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	(352)	746	1
Impact of net unrealized investment (gains) losses on future policy benefits	(128)	183	0
Ending Balance	(3,263)	1,387	14
OTTI | Accumulated Other Comprehensive Income (Loss) Related To Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,529)	20	17
Net investment gains (losses) on investments arising during the period	7,847	246	(6)
Reclassification adjustment for (gains) losses included in net income	1,505	361	11
Reclassification adjustment for OTTI losses excluded from net income	50	(1,433)	0
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs and other costs	773	(1,384)	(2)
Impact of net unrealized investment (gains) losses on future policy benefits	237	(339)	0
Ending Balance	$ 7,883	$ (2,529)	$ 20