DEBT (Details - Revolving Credit Facility)		3 Months Ended
	Dec. 10, 2019 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Oct. 26, 2018 USD ($)
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount		$ 200,000		$ 200,000
Credit Agreement, Potential Additional Borrowing Capacity	$ 185,000,000.0
Long-term Debt, Current Maturities		$ 130,000,000		$ 75,000,000.0
Long-term Debt, Weighted Average Interest Rate, at Point in Time		2.21%		3.01%
Ratio of Debt to EBITDA Step-Down	4.0
Ratio of Debt to EBITDA Increase	0.5
Interest Expense, Debt		$ 4,000,000.0	$ 3,800,000
Debt Instrument, Unused Borrowing Capacity, Fee		300,000	100,000
Amortization of debt issuance costs		582,000	483,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500,000,000.0				$ 350,000,000.0
Revolving Credit Facility, term	5 years
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					$ 2,800,000
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%
Interest Expense, Debt		600,000	1,900,000
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
Line of Credit Facility [Line Items]
Interest Expense, Debt		1,100,000	2,100,000
Amortization of debt issuance costs		$ 200,000	$ 100,000
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				$ 25,000,000.0