Segment Information - Segment Revenues and Earnings (Detail) (USD $)	3 Months Ended									12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 80,316,000	[1]	$ 58,840,000	$ 83,013,000	$ 84,605,000	$ 98,388,000	$ 75,107,000	$ 60,079,000	$ 97,471,000	$ 306,774,000		$ 331,045,000		$ 172,591,000
Depreciation, depletion and amortization										41,715,000		29,980,000		18,926,000
Equity in earnings of unconsolidated ventures	4,720,000	[1]	2,016,000	958,000	991,000	2,133,000	3,125,000	2,566,000	913,000	8,685,000		8,737,000		14,469,000
Income (loss) before taxes										25,240,000		36,529,000		20,958,000
Total assets	1,258,199,000					1,172,152,000				1,258,199,000		1,172,152,000		918,434,000
Investment in unconsolidated ventures	65,005,000					41,147,000				65,005,000		41,147,000		41,546,000
Capital expenditures										138,798,000	[2]	107,897,000	[2]	24,151,000	[2]
Operating Segments [Member] | Real Estate [Member]
Segment Reporting Information [Line Items]
Revenues										213,112,000		248,011,000		120,115,000
Depreciation, depletion and amortization										3,741,000		3,117,000		4,340,000
Equity in earnings of unconsolidated ventures										8,068,000		8,089,000		13,897,000
Income (loss) before taxes										96,906,000		68,454,000		53,582,000
Total assets	654,774,000					582,802,000				654,774,000		582,802,000		588,137,000
Investment in unconsolidated ventures	65,005,000					41,147,000				65,005,000		41,147,000		41,546,000
Capital expenditures										28,980,000	[2]	7,265,000	[2]	1,093,000	[2]
Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Revenues										84,300,000		72,313,000		44,220,000
Depreciation, depletion and amortization										29,442,000		19,552,000		4,987,000
Equity in earnings of unconsolidated ventures										586,000		592,000		509,000
Income (loss) before taxes										(22,686,000)		18,859,000		26,608,000
Total assets	342,703,000					312,553,000				342,703,000		312,553,000		227,061,000
Investment in unconsolidated ventures	0					0				0		0		0
Capital expenditures										103,385,000	[2]	97,696,000	[2]	21,971,000	[2]
Operating Segments [Member] | Other Natural Resources [Member]
Segment Reporting Information [Line Items]
Revenues										9,362,000		10,721,000		8,256,000
Depreciation, depletion and amortization										497,000		651,000		1,254,000
Equity in earnings of unconsolidated ventures										31,000		56,000		63,000
Income (loss) before taxes										5,499,000		6,507,000		29,000
Total assets	22,531,000					23,478,000				22,531,000		23,478,000		24,066,000
Investment in unconsolidated ventures	0					0				0		0		0
Capital expenditures										5,817,000	[2]	2,720,000	[2]	292,000	[2]
Items Not Allocated To Segments [Member]
Segment Reporting Information [Line Items]
Revenues										0		0		0
Depreciation, depletion and amortization										8,035,000		6,660,000		8,345,000
Equity in earnings of unconsolidated ventures										0		0		0
Income (loss) before taxes										(54,479,000)	[3]	(57,291,000)	[3]	(59,261,000)	[3]
Total assets	238,191,000					253,319,000				238,191,000		253,319,000		79,170,000
Investment in unconsolidated ventures	0					0				0		0		0
Capital expenditures										$ 616,000	[2]	$ 216,000	[2]	$ 795,000	[2]

[1] Fourth quarter 2014 results include pre-tax non-cash impairment charges of $30,591,000 for unproved leasehold interests and proved oil and gas properties.

[2] Consists of expenditures for oil and gas properties and equipment, commercial and income producing properties, property, plant and equipment and reforestation of timber.

[3] Items not allocated to segments consist of: For the Year 2014 2013 2012 (In thousands)General and administrative expense$(21,229) $(20,597) $(25,176)Share-based compensation expense(3,417) (16,809) (14,929)Gain on sale of assets— — 16Interest expense(30,286) (20,004) (19,363)Other corporate non-operating income453 119 191 $(54,479) $(57,291) $(59,261)