Subsequent Event (Details) (USD $)	Feb. 03, 2012
Subsequent Event [Line Items]
Ownership interest in co investment	100.00%
Acquisition [Member]
Subsequent Event [Line Items]
Business acquisition, percentage of interest acquired	63.00%
Business acquisition, loan repayment	335,000,000
Real Estate assumed, fair value	1,600,000,000
Business acquisition, debt assumed	835,000,000