OTHER INCOME (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Income and Expenses [Abstract]
Equity investment income	$ 1,016	$ 1,391	$ 3,199	$ 2,741
Interest income	456	872	1,605	2,646
Building rental income	381	594	1,369	1,789
Investment gain related to investments for deferred compensation	0	480	688	1,827
Other income (expense)	5,584	(768)	10,803	(2,007)
Nonoperating Income (Expense)	$ 7,437	$ 2,569	$ 17,664	$ 6,996

Amount of realized and unrealized gain (loss) on investment.

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