Segment Information - Segment Revenues and Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 28,015	$ 47,992	$ 50,320	$ 85,610
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	8,120	26,591	49,118	32,583
General and administrative expense	(28,372)	(4,852)	(33,063)	(11,331)
Gain on sale of assets	29,506	107,650	103,721	121,231
Interest expense	(2,166)	(6,918)	(4,401)	(14,557)
Loss on extinguishment of debt, net	0	(35,766)	0	(35,864)
Other corporate non-operating income	622	199	1,298	371
Segment Earnings
Segment Reporting Information [Line Items]
Total revenues	28,015	47,992	50,320	85,610
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	10,893	74,026	58,795	94,222
Items Not Allocated to Segments
Segment Reporting Information [Line Items]
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(2,773)	(47,435)	(9,677)	(61,639)
General and administrative expense	(27,549)	(4,514)	(31,577)	(9,487)
Shared-based and long-term incentive compensation expense	(1,448)	(412)	(2,343)	(1,956)
Gain on sale of assets	28,049	0	28,049	0
Interest expense	(2,166)	(6,918)	(4,401)	(14,557)
Loss on extinguishment of debt, net	0	(35,766)	0	(35,864)
Other corporate non-operating income	341	175	595	225
Real estate | Segment Earnings
Segment Reporting Information [Line Items]
Total revenues	27,992	46,381	48,744	82,479
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	11,545	73,290	22,018	93,514
Mineral resources | Segment Earnings
Segment Reporting Information [Line Items]
Total revenues	5	1,337	1,502	2,419
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(348)	933	37,468	1,486
Other | Segment Earnings
Segment Reporting Information [Line Items]
Total revenues	18	274	74	712
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	$ (304)	$ (197)	$ (691)	$ (778)