OTHER INCOME (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Income and Expenses [Abstract]
Income (Loss) from Equity Method Investments	$ 1,391	$ 840	$ 2,741	$ 2,423
Interest Income, Other	872	929	2,646	2,182
Gain (Loss) on Investments	480	560	1,827	52
Rental Income, Nonoperating	594	557	1,789	1,528
Amortization of Prepaid Royalty Discount	180	389	689	1,168
Gain (Loss) on Disposition of Assets	(542)	(71)	(734)	2,271
Other Nonoperating Income (Expense)	66	374	(560)	908
Nonoperating Income (Expense)	$ 3,041	$ 3,578	$ 8,398	$ 10,532

The expense charged against earnings for the periodic recognition of the advance royalties. These royalties are paid in one accounting period, but are deducted from earnings over time through amortization. For example, royalties that are required to be paid in advance of production from a mineral, oil, or gas property and amortized over the period of right to produce these items.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
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-Section S99
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-Subparagraph (SX 210.5-03.3)
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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

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Amount of interest income earned from interest bearing assets classified as other.

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