FINANCIAL INSTRUMENTS Level 3 reconciliation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 6,861,000	$ 6,573,000	$ 6,763,000	$ 8,957,000
Purchases			1,750,000
Sales				(2,539,000)
Total realized and unrealized gains (losses) and amortization included in earnings, net		180,000		335,000
Transfers out of Level 3	0		(1,768,000)	0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	(1,348,000)		(1,348,000)		$ 0
Ending balance	6,961,000	6,753,000	6,961,000	6,753,000
Debt instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	776,000	586,000	654,000	505,000
Purchases			0
Sales				0
Total realized and unrealized gains (losses) and amortization included in earnings, net	58,000	56,000	180,000	137,000
Transfers out of Level 3			0
Ending balance	834,000	642,000	834,000	642,000
Private equity and limited partnerships (1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	6,085,000	5,987,000	6,109,000	8,452,000
Purchases			1,750,000
Sales				(2,539,000)
Total realized and unrealized gains (losses) and amortization included in earnings, net	42,000	124,000	36,000	198,000
Transfers out of Level 3			1,768,000
Ending balance	6,127,000	6,111,000	6,127,000	6,111,000
Financial contracts payable
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) and amortization included in earnings, net	100,000		216,000
Net investment income (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains (losses) and amortization included in earnings, net	0	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	100,000	200,000	200,000	1,700,000
Quoted prices in active markets (Level 1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of Level 3		0		0
Quoted prices in active markets (Level 1) | Total equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0		0
Significant other observable inputs (Level 2) | Private equity and limited partnerships (1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of Level 3			1,800,000
Significant other observable inputs (Level 2) | Financial contracts receivable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Significant other observable inputs (Level 2) | Total equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of Level 3		0		0
Significant other observable inputs (Level 2) | Financial contracts payable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of Level 3		0		0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers into Level 3	$ 0	$ 0	$ 0	$ 0