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Equity Investments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended				0 Months Ended
	Oct. 09, 2009 Tres Amigas [Member]	Jun. 30, 2011 Tres Amigas [Member]	May 20, 2011 Tres Amigas [Member]	Jan. 06, 2011 Tres Amigas [Member]	Aug. 12, 2010 Blade Dynamics Ltd. [Member]	Jun. 30, 2011 Blade Dynamics Ltd. [Member]
Acquisition date	October 9, 2009				August 12, 2010
Equity method investment, aggregate cost	$ 1.8
Equity method investment in cash	0.8
Equity method investment in common stock	1.0
Cash consideration for increase in minority position			$ 1.8	$ 1.8
Equity method investment ownership percentage		37.00%				25.00%

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Cash consideration for increase in minority position

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- Definition

Equity method investment in cash.

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- Definition

Month, date and year when the results of operations of the acquired entity began to be included in the income statement of the combined entity. For disclosure purposes, the effective date of an acquisition equates to the acquisition date, when acquisition date is defined as the date on which the acquirer obtained control of the acquired entity. The effective date of an acquisition may be either earlier or later than the date on which the acquisition agreement was executed (closed).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 10, 11

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 3
-Subparagraph c

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph b

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- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 12
-Article 5

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph f

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 18
-Paragraph 20
-Subparagraph a (1)

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment losses recognized.

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