DEBT (Details - Revolving Credit Facility)		9 Months Ended
	Nov. 21, 2017 USD ($)	Sep. 30, 2019 USD ($) Rate	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) Rate	Oct. 26, 2018 USD ($)
Line of Credit Facility [Line Items]
Long-term Debt, Current Maturities		$ 85,000,000		$ 125,000,000
Long-term Debt, Weighted Average Interest Rate, at Point in Time | Rate		3.55%		4.02%
Ratio of Debt to EBITDA Step-Down	4.0
Ratio of Debt to EBITDA Increase	0.5
Interest Expense, Debt		$ 11,500,000	$ 10,900,000
Debt Instrument, Unused Borrowing Capacity, Fee		500,000	600,000
Amortization of debt issuance costs		1,463,000	1,308,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 250,000,000.0				$ 350,000,000.0
Revolving Credit Facility, term	5 years
Revolving Credit Facility, conditional increase to borrowing capacity	$ 100,000,000.0
Increase in borrowing capacity					100,000,000.0
Revolving Credit Facility, collateral, percent of assets	100.00%
Revolving Credit Facility, collateral, percent of equity	100.00%
Revolving Credit Facility, letter of credit fronting fee percentage	0.125%
Fees and expense paid to lenders at closing					$ 500,000
Line of Credit Facility, Collateral, Percent of Domestic Subsidiaries Equity	100.00%
Line of Credit Facility, Collateral, Percent of Voting Equity	66.00%
Line of Credit Facility, Collateral, Percent of Non-Voting Equity	100.00%
Swingline Facility [Member]
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 10,000,000.0
Letters of Credit [Member]
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 10,000,000.0
Fed Funds Effective Rate Overnight Index Swap Rate [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	0.50%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	1.00%
Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, unused capacity, commitment fee percentage	0.25%
Revolving Credit Facility, letter of credit participation fee percentage	1.25%
Minimum | London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	1.25%
Minimum | Base Rate [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	0.25%
Maximum
Line of Credit Facility [Line Items]
Ratio of Debt to EBITDA to Increase Revolving Commitment	2.50
Ratio of Debt to EBITDA	4.5
Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, unused capacity, commitment fee percentage	0.45%
Revolving Credit Facility, letter of credit participation fee percentage	2.00%
Maximum | London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	2.00%
Maximum | Base Rate [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving Credit Facility, basis spread on variable rate	1.00%
Revolving Credit Facility, Borrowings At Base Rate Plus LIBOR [Member]
Line of Credit Facility [Line Items]
Interest Expense, Debt		4,200,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest Expense, Debt		5,100,000
Amortization of debt issuance costs		400,000	$ 300,000
Revolving Credit Facility, 31 Day Borrowing | Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt, Current Maturities		50,000,000.0
Revolving Credit Facility, 32 Day Borrowing | Revolving Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt, Current Maturities		$ 35,000,000.0