Investments (Tables)

9 Months Ended

Sep. 30, 2017

Investment in Marketable Securities [Abstract]

Investments

These investments are classified as available-for-sale and are measured at fair value in the financial statements with unrealized gains and losses recorded in Other comprehensive income (loss).

	At September 30, 2017
In thousands	Cost		Gross Unrealized Losses			Gross Unrealized Gains		Estimated Fair Value
Equity Securities
Metalla Royalty & Streaming Ltd.	$	6,294	$	—		$	817	$	7,111
Corvus Gold Inc.	3,582		—			542		4,124
Almaden Minerals, Ltd.	3,125		—			102		3,227
Northern Empire Resources Corp.	2,999		—			378		3,377
Rockhaven Resources, Ltd.	2,064		(364		)	—		1,700
Kootenay Silver, Inc.	928		—			40		968
Other	1,482		(82		)	566		1,966
Equity securities	$	20,474	$	(446	)	$	2,445	$	22,473
Debt Securities
Metalla Royalty & Streaming Ltd.	$	6,677	$	(25	)	$	—	$	6,652
Equity and debt securities	$	27,151	$	(471	)	$	2,445	$	29,125

	At December 31, 2016
In thousands	Cost		Gross Unrealized Losses		Gross Unrealized Gains		Estimated Fair Value
Kootenay Silver, Inc.	$	2,645	$	—	$	—	$	2,645
Silver Bull Resources, Inc.	233		—		783		1,016
Other	229		—		598		827
Equity securities	$	3,107	$	—	$	1,381	$	4,488

Schedule of Unrealized Loss on Investments [Table Text Block]

The following table summarizes unrealized losses on equity and debt securities for which other-than-temporary impairments have not been recognized and the fair values of those securities, aggregated by the length of time the individual securities have been in a continuous unrealized loss position, at September 30, 2017:

	Less than twelve months				Twelve months or more				Total
In thousands	Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value
Equity securities	$	446	$	2,046	$	—	$	—	$	446	$	2,046
Debt securities	25		6,652		—		—		25		6,652