MORTGAGE LOAN RECEIVABLES - Activity in Loan Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Activity in loan portfolio
Balance at the beginning of the period, provision for loan losses			$ (4,000)
Realized gain on sale of mortgage loan receivables	$ (6,144)	$ (25,904)	(11,032)	$ (24,905)
Loan loss provision	(300)	0	(3,300)	0
Balance at the end of the period, provision for loan losses	(7,300)		(7,300)
Loans held for sale transferred loan held for investment, book value	57,600	120,000	57,600	120,000
Loans held for sale transferred to loans held for investments, fair value	55,400	119,900	$ 55,400	$ 119,900
Loans from held for sale transferred to portfolio loans, remaining maturity			2 years 6 months 7 days	3 years
Mortgage loans held by consolidated subsidiaries
Activity in loan portfolio
Balance at the beginning of the period			$ 3,282,462	$ 2,000,095
Origination of mortgage loan receivables			914,489	563,392
Purchases of mortgage loan receivables			0	94,079
Repayment of mortgage loan receivables			(497,124)	(155,325)
Proceeds from sales of mortgage loan receivables			0	0
Realized gain on sale of mortgage loan receivables			0	0
Transfer between held for investment and held for sale			55,403	119,952
Accretion/amortization of discount, premium and other fees			8,942	4,539
Loan loss provision			0
Balance at the end of the period	3,764,172	2,626,732	3,764,172	2,626,732
Mortgage loan receivables held for investment, net, at amortized cost
Activity in loan portfolio
Balance at the beginning of the period, provision for loan losses			(4,000)	(4,000)
Loan loss provision			(3,300)
Balance at the end of the period, provision for loan losses	(7,300)	(4,000)	(7,300)	(4,000)
Mortgage loan receivables held for sale
Activity in loan portfolio
Balance at the beginning of the period			230,180	357,882
Origination of mortgage loan receivables			764,948	564,492
Purchases of mortgage loan receivables			0	0
Repayment of mortgage loan receivables			(286)	(1,184)
Proceeds from sales of mortgage loan receivables			(842,727)	(563,929)
Realized gain on sale of mortgage loan receivables			(11,032)	(24,905)
Transfer between held for investment and held for sale			(55,403)	(119,952)
Accretion/amortization of discount, premium and other fees			0	0
Loan loss provision			0
Balance at the end of the period	107,744	262,214	107,744	262,214
Realized losses on loans recorded as other than temporary impairments	$ 500	$ 1,000	$ 500	$ 1,000

Loans From Held For Sale Transferred To Portfolio Loans, Remaining Maturity

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- Definition

Loans Held-for-sale Transferred to Portfolio Loans, Carrying Amount

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Loans Held-for-sale Transferred to Portfolio Loans, Fair Value

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- Definition

Represents the amount of accretion/ amortization of discount, premium and other fees on mortgage loans on real estate accreted/ amortized during the reporting period.

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Mortgage Loans on Real Estate, Purchases of Mortgage Loans

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Transfer To (From) Loans Held-for-sale to Portfolio Loans

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Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from collection of principal.

+ References

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Amount of increase (decrease) of allowance reserve for credit loss.

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The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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- Definition

Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

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Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from sale.

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Amount of increase in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from new investment.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

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- Definition

Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

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