FAIR VALUE MEASUREMENTS (Narrative) (Details)	3 Months Ended
Mar. 31, 2019 USD ($) item	Mar. 31, 2018 USD ($)
FAIR VALUE MEASUREMENTS [Abstract]
Number of Rabbi Trusts established \| item	2
Net gains (losses) of the Rabbi Trust investments	$ 1,863,000	$ (776,000)
Unrealized net gains (losses) of the Rabbi Trust investments	$ 1,905,000	$ (787,000)

Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

No definition available.

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration