INVESTMENTS - Fixed Income Securities By Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized cost of available-for-sale debt securities by contractual maturity
Due in one year or less	$ 49,951
Due after one year through five years	395,056
Due after five years through 10 years	580,310
Due after 10 years	255,321
Total amortized cost	1,915,278	$ 1,776,465
Fair value of available-for-sale debt securities by contractual maturity
Due in one year or less	50,170
Due after one year through five years	407,007
Due after five years through 10 years	613,099
Due after 10 years	267,775
Total fair value	1,983,086	$ 1,760,515
Mtge/ABS/CMBS
Amortized cost of available-for-sale debt securities by contractual maturity
Total amortized cost	634,640
Fair value of available-for-sale debt securities by contractual maturity
Total fair value	$ 645,035

Amortized cost of 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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