INCOME TAXES- Reconciliations of Income tax expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed income tax at statutory rate	$ (24,173)	$ (50,801)	$ (10,810)
Federal and state taxes	(2,335)	0	(190)
Benefit of net exempt income	16,596	14,995	9,780
Deferred tax valuation allowance	10,037	5,976	2,881
Income Tax Rate Reconciliation Prior Periods Income Tax Returns	(607)	(434)	1,174
Non-tax deductible expenses	(467)	(212)	365
Income Tax Reconciliation Change In Tax Status	13,161	0	0
Income Tax Rate Reconciliation NOL Carryforwards	(5,091)	(6,396)	(7,717)
Income Tax Reconciliation Effect Of Capital Losses Subject To Preferential Rates	(2,102)	(727)	(3,019)
Other-net	(46)	569	1,117
Total income tax provision	$ 4,973	$ (37,030)	$ (6,419)
Statutory rate	(39.00%)	(39.00%)	(39.00%)
Federal and state taxes %	(3.80%)	0.00%	(0.70%)
Benefit of net exempt income %	26.80%	11.50%	35.30%
Deferred tax valuation allowance %	16.20%	4.60%	10.40%
Non-tax deductible expenses %	(0.80%)	(0.20%)	1.30%
Effective Income Tax Reconciliation Effect Of Capital Losses Subject To Preferential Rates	(3.40%)	(0.60%)	(10.90%)
Effective Income Tax Rate Reconciliations Prior Periods Income Tax Returns	(1.00%)	(0.30%)	4.20%
Effective Income Tax Rate Reconciliation Change In Tax Status	21.20%	0.00%	0.00%
Other-net %	0.00%	0.30%	4.00%
Total income tax provision %	8.00%	(28.60%)	(23.20%)
Effective Income Tax Rate Reconciliations NOL Carryforwards	(8.20%)	(4.90%)	(27.80%)

Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to the change in tax status of certain subsidiaries from taxable corporations to limited liability companies.

No definition available.