SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property and equipment
Total property and equipment, gross	$ 193,236	$ 109,423
Accumulated depreciation	(33,199)	(22,926)
Land	24,920	24,920
Total property and equipment	$ 184,957	111,417
Home office building
Property and equipment
Useful life	25 years
Total property and equipment, gross	$ 144,669	68,123
Furniture
Property and equipment
Useful life	10 years
Office equipment and machines
Property and equipment
Useful life	5 years
Software and computers
Property and equipment
Useful life	4 years
Data processing equipment
Property and equipment
Total property and equipment, gross	$ 28,793	24,102
Other, principally furniture and equipment
Property and equipment
Total property and equipment, gross	$ 19,774	$ 17,198

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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