INCOME TAXES, Reconciliation of Income taxes Computed at the Statutory Federal Income Tax Rate to Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of income taxes to the statutory rate [Abstract]
Statutory federal income tax rate	21.00%								31.50%	35.00%	35.00%
Income tax expense computed at the U.S. statutory federal rate									$ 26,505	$ 30,134	$ 26,513
Effect of federal reduction of statutory rate									(1,654)
State income tax expense - net of federal benefit									3,842	4,193	3,544
Non-deductible executive compensation									658	512	331
Other									(582)	717	616
Provision for income taxes	$ 9,270	$ 678	$ 11,466	$ 7,355	$ 8,246	$ 8,687	$ 11,808	$ 6,815	$ 28,769	$ 35,556	$ 31,004
Effective income tax rate									34.30%	41.30%	40.90%