Segment Information - Segment Revenues and Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total revenues	$ 41,888	$ 47,805
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(7,002)	(12,517)
General and administrative expense	6,479	8,142
Interest expense	7,639	8,821
Other corporate non-operating income	74	917
Segment Earnings
Segment Reporting Information [Line Items]
Total revenues	41,888	47,805
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	7,202	5,734
Segment Earnings | Real estate
Segment Reporting Information [Line Items]
Total revenues	36,098	32,830
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	20,224	9,066
Segment Earnings | Oil and Gas
Segment Reporting Information [Line Items]
Total revenues	5,352	13,185
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(12,441)	(2,941)
Segment Earnings | Other natural resources
Segment Reporting Information [Line Items]
Total revenues	438	1,790
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(581)	(391)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Segment reporting information income (loss) from continuing operations before income taxes attributable to parent	(14,204)	(18,251)
General and administrative expense	(4,973)	(6,020)
Shared-based and long-term incentive compensation expense	(1,544)	(3,458)
Interest expense	(7,639)	(8,821)
Other corporate non-operating income	$ (48)	$ 48