INCOME TAXES (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
U.S. federal corporate income tax rate			21.00%		35.00%
Tax Cuts and Jobs Act of 2017, percent of immediate deductibility of certain capital investments			100.00%
Tax Cuts and Jobs Act of 2017, incomplete accounting, provisional expense, deferred tax assets, executive compensation					$ 1,403,000
Income tax expense	$ 40,663,000	$ 39,080,000	$ 75,805,000	$ 81,557,000
Tax Cuts and Jobs Act of 2017, incomplete accounting, provisional transition tax, foreign repatriation					$ 12,301,000
Income tax benefit recognition threshold more likely than not			50.00%
Release of unrecognized tax benefit liability	$ 7,157,000
Forecast [Member]
Operating Loss Carryforwards [Line Items]
State net operating loss carryforwards						$ 72,160,000
Net operating loss carryforwards, valuation allowance						29,696,000
Alabama [Member] | State [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration date			Dec. 31, 2023
Alabama [Member] | State [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration date			Dec. 31, 2033
Alabama [Member] | Forecast [Member]
Operating Loss Carryforwards [Line Items]
State net operating loss carryforwards						67,688,000
Net operating loss carryforwards, valuation allowance						$ 29,182,000