Investments - Cost or Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 834,817	$ 831,127
Gross Unrealized Gains	10,923	1,922
Gross Unrealized Losses	(5,712)	(12,611)
Fair Value	840,028	820,438
U.S. Government Obligations and Agencies [Member] \| Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	65,888	67,435
Gross Unrealized Gains	408	241
Gross Unrealized Losses	(654)	(1,039)
Fair Value	65,642	66,637
Corporate Bonds [Member] \| Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	422,426	434,887
Gross Unrealized Gains	6,650	714
Gross Unrealized Losses	(1,643)	(6,736)
Fair Value	427,433	428,865
Mortgage-Backed and Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	330,925	312,840
Fair Value	331,767	309,597
Mortgage-Backed and Asset-Backed Securities [Member] \| Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	330,925	312,840
Gross Unrealized Gains	3,585	912
Gross Unrealized Losses	(2,743)	(4,155)
Fair Value	331,767	309,597
Municipal Bonds [Member] \| Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,403	3,405
Gross Unrealized Gains	25	0
Gross Unrealized Losses	(8)	(43)
Fair Value	3,420	3,362
Redeemable Preferred Stock [Member] \| Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,175	12,560
Gross Unrealized Gains	255	55
Gross Unrealized Losses	(664)	(638)
Fair Value	$ 11,766	$ 11,977

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
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-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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-Topic 320
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
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