Business Segment and Geographic Information (Reconciliation to Consolidated Statements of Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting [Abstract]
Operating Income (Loss)	$ 80,427us-gaap_OperatingIncomeLoss	$ 49,280us-gaap_OperatingIncomeLoss	$ 25,664us-gaap_OperatingIncomeLoss
Equity income in unconsolidated joint ventures	4,123	4,326	4,743
Other income (expense), net	(1,194)us-gaap_OtherNonoperatingIncomeExpense	(1,240)us-gaap_OtherNonoperatingIncomeExpense	(208)us-gaap_OtherNonoperatingIncomeExpense
Net realized investment gain (loss)	0us-gaap_RealizedInvestmentGainsLosses	0us-gaap_RealizedInvestmentGainsLosses	(3,245)us-gaap_RealizedInvestmentGainsLosses
Interest income (expense), net	(2,946)	(3,481)	(4,304)
Income (loss) before income taxes	$ 80,410	$ 48,885	$ 22,650

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 25

-Paragraph 1

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-Name Accounting Standards Codification

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Article 5

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- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

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

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-Name Accounting Standards Codification

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-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Name Accounting Standards Codification

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-Name Accounting Standards Codification

-Topic 225

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-Number 210

-Section 04

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- Definition

The net amount of nonoperating interest income (expense).

+ References

No definition available.

+ Details

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

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- Definition

The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items.

+ References

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

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- Definition

The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

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-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 3

-Subparagraph a

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