CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
Royalties	$ 3,224	$ 5,205
Miscellaneous income	42	56
Total revenues	3,266	5,261
Operating expenses:
General and administrative	721	583
Total operating expenses	721	583
Operating income and income before income tax expense (benefit)	2,545	4,678
Income tax expense (benefit)	1,028	(2,495)
Net income	$ 1,517	$ 7,173
Earnings per common share:
Basic (in dollars per share)	$ 0.03	$ 0.16
Diluted (in dollars per share)	$ 0.03	$ 0.16
Weighted-average shares outstanding - basic	44,214	44,181
Weighted-average shares outstanding - diluted	44,214	44,227