Available For Sale Investments (Tables)

9 Months Ended

Sep. 30, 2012

Investments, Debt and Equity Securities [Abstract]

Available for Sale Investments

The following table presents changes in available for sale investments in the first nine months of 2012 and the full year 2011:

	As of September 30, 2012					As of December 31, 2011
	Riverstone					Riverstone
	Fair Value			Shares		Fair Value		Shares
Balance at beginning of period	$	1,416		2,000,000		$	928	1,300,000
Acquisitions	17,117			23,676,301		469		700,000
Dispositions	(445		)	(638,700	)	—		—
OCI - unrealized (loss)/gain	(271		)	—		19		—
Balance at end of period	$	17,817		25,037,601		$	1,416	2,000,000