Discontinued Operations (Details Textual) (USD $)	1 Months Ended		6 Months Ended
	May 31, 2012	Apr. 30, 2012	Jun. 30, 2012	Jul. 31, 2012	Dec. 31, 2011
Discontinued Operations (Textual) [Abstract]
Purchase price of oil and gas business		$ 72,600,000
Current liabilities of discontinued operations			63,912,000	63,900,000	54,287,000
Noncurrent liabilities related to discontinued operations			35,300,000		71,400,000
Cumulative cash receipts	5,700,000
Approximate commitments beyond December 31, 2013 if the related properties are not sold			265,400,000
Gain on sale of oil and gas operations		48,500,000	48,486,000
Oil and Gas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Adjusted carrying value of aircraft logistics assets			7,200,000
Canada [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Adjusted carrying value of aircraft logistics assets			$ 5,200,000