Subsequent Events (Textuals) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	75.0
XTXI Credit Facility [Member]
Subsequent Event [Line Items]
SubsequentEventsDate	May 08, 2013
E2 Investment [Member]
Subsequent Event [Line Items]
Payments To Acquire Other Investments	25.0
Pre Amendment [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	75.0
Post Amendment [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	90.0