Reconciliation of income tax expense (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of income tax expense
Corporate tax rate applied to to the income before income taxes	35.00%
Computed expected income tax (benefit) expense	$ 14,762	$ 26,998	$ (4,211)
Book to tax differences for partnerships not consolidated for tax purposes	(23,900)	(33,565)	(3,831)
Book to tax differences of depreciation and amortization	1,461	1,222	1,434
Book to tax differences in gains on sale of property	(2,350)	(20,308)	(4,835)
Book provision for loss		3,962fil_BookProvisionForLoss	1,656fil_BookProvisionForLoss
Partial valuation allowance against current net operating loss benefit	7,069	16,835	10,401
Other differences	2,958	2,139	(614)
Total differences		(2,717)
Alternative minimum tax			$ 0

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

No definition available.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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No definition available.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deductions. Including, but not limited to, extraterritorial income exclusion deduction, qualified production activity deduction, dividend deduction, deduction for dividend paid to employee stock ownership plan, Medicare prescription drug benefit subsidy deduction, and other deductions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax settlements. Including, but not limited to, domestic tax settlement, foreign tax settlement, state and local tax settlement, and other tax settlements.

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