Noncontrolling Interest (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended		1 Months Ended	6 Months Ended
	Jun. 30, 2012 Installment	Jun. 30, 2011 Installment	Dec. 31, 2010 GeoCam [Member]	Jun. 30, 2011 GeoCam [Member]	Jun. 30, 2012 GeoCam [Member]	Dec. 31, 2011 GeoCam [Member]	May 31, 2010 GeoCam [Member]
Noncontrolling Interest (Textual) [Abstract]
Increase in authorized capital amount							$ 11
Number of cash calls	0
Number of cash calls completed		2
Cash calls equivalent				8.2
Payments to acquire additional interest in subsidiaries				5.0
Cash paid for cash calls made				0.605
Noncontrolling interest cash paid				3.2
Noncontrolling interest balance					9.4	9.9
Additional capital increase approved			$ 13