INVESTMENTS - Other Invested Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other invested assets
Other Investments	$ 70,441	$ 51,542
Qualified Affordable Housing Project Investments, Commitment	8,600
Investments pledged as collateral	$ 15,500
Investment in Federal Home Loan Bank Stock	us-gaap:AssetPledgedAsCollateralMember
Federal Home Loan Bank Borrowings, Fair Value Disclosure	$ 0
Investment In Low Income Housing Tax Credit Partnership Net Of Amortization
Other invested assets
Other Investments	23,300	20,300
Qualified Affordable Housing Project Investments, Commitment	8,600
Total tax benefit on investments in housing tax credit partnership	2,500	2,200	$ 2,400
Investment in Private Funds
Other invested assets
Other Investments	46,000	$ 30,300
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 15,500