CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
General and administrative expense	$ 4,849	$ 4,754	$ 10,077	$ 9,634
Operating loss	(4,849)	(4,754)	(10,077)	(9,634)
Other income (loss), net	659	(15)	659	(403)
Interest income	527	640	947	1,089
Interest expense	(1,155)	(1,128)	(2,304)	(2,250)
Equity income (loss)	43,794	(13,765)	34,299	(22,427)
Net income (loss) before income taxes	38,976	(19,022)	23,524	(33,625)
Income tax benefit (expense)	0	0	0	0
Net income (loss)	$ 38,976	$ (19,022)	$ 23,524	$ (33,625)
Net income (loss) per share:
Basic (in dollars per share)	$ 1.92	$ (0.91)	$ 1.15	$ (1.61)
Diluted (in dollars per share)	$ 1.70	$ (0.91)	$ 1.09	$ (1.61)
Weighted average shares used in computing income (loss) per share:
Basic (in shares)	20,333	20,895	20,391	20,878
Diluted (in shares)	23,539	20,895	23,602	20,878