MARKETABLE SECURITIES (Notes)

12 Months Ended

Dec. 31, 2018

Marketable Securities [Abstract]

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

MARKETABLE SECURITIES:

Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2018, were as follows:

	Amortized		Gross Unrealized					Estimated Fair
(in thousands)	Cost		Gains		Losses			Market Value
Investments due in 3 months or less:
Corporate securities	$	6,788	$	—	$	(2	)	$	6,786
Total	6,788		—		(2		)	6,786
Investments due in 4-12 months:
Corporate securities	60,123		—		(244		)	59,879
Total	60,123		—		(244		)	59,879
Investments due in 12 months or greater:
Corporate securities	27,806		2		(22		)	27,786
Total	27,806		2		(22		)	27,786
Total marketable securities	$	94,717	$	2	$	(268	)	$	94,451

Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2017, were as follows:

	Amortized		Gross Unrealized					Estimated Fair
(in thousands)	Cost		Gains		Losses			Market Value
Investments due in 3 months or less:
Corporate securities	$	38,485	$	—	$	(16	)	$	38,469
Total	38,485		—		(16		)	38,469
Investments due in 4-12 months:
Corporate securities	104,440		—		(199		)	104,241
Government securities	9,302		—		(17		)	9,285
Total	113,742		—		(216		)	113,526
Investments due in 12 months or greater:
Corporate securities	37,436		—		(195		)	37,241
Total	37,436		—		(195		)	37,241
Total marketable securities	$	189,663	$	—	$	(427	)	$	189,236

The weighted average interest rate of investments at December 31, 2018 and 2017, was approximately 2.65% and 1.57%, respectively. As of December 31, 2018 and 2017, there were no individual securities that had been in a continuous loss position for 12 months or greater.