INCOME TAXES- Reconciliations of Income tax expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed income tax at statutory rate	$ 74,349	$ 24,173	$ 50,801
Federal and state taxes	3,768	2,335	0
Benefit of net exempt income	(22,782)	(16,596)	(14,995)
Disallowed NOL carryforward resulting from net exempt income	14,904	5,091	6,396
Deferred tax valuation allowance	(90,521)	(10,037)	(5,976)
Adjustment for enacted changes in tax law	15,402	138	(20)
Change in tax status of subsidiaries	0	(13,161)	0
Share based compensation windfull	(1,595)	(40)	92
Effect of capital losses subject to preferential rates	0	2,102	727
Non deductible expenses and other permanent differences	(839)	(470)	(1,720)
Tax return to provision adjustments	4	607	434
Other-net	(3,660)	885	1,291
Total income tax (benefit) expense	$ (10,970)	$ (4,973)	$ 37,030
Computed income tax at statutory tax rate %	39.00%	39.00%	39.00%
Federal and state taxes %	2.00%	3.80%	0.00%
Benefit of net exempt income %	(12.00%)	(26.80%)	(11.50%)
Disallowed NOL carryforward resulting from net exempt income %	7.80%	8.20%	4.90%
Deferred tax valuation allowance %	(47.50%)	(16.20%)	(4.60%)
Adjustments in net deferred tax assets due to changes in enacted tax rates %	8.10%	0.20%	0.00%
Change in tax status of subsidiaries %	0.00%	(21.20%)	0.00%
Share based compensation windfall %	(0.80%)	0.00%	0.10%
Effective Income Tax Reconciliation Effect Of Capital Losses Subject To Preferential Rates	0.00%	3.40%	0.60%
Non-tax deductible expenses and other permanent differences %	(0.40%)	(0.80%)	(1.20%)
Tax-return provision adjustments %	0.00%	1.00%	0.30%
Other-net %	(1.90%)	1.40%	1.00%
Total income tax (benefit) expense %	(5.70%)	(8.00%)	28.60%