Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013 item
Variable Interest Entities
Number of VIEs related to securities investments	1
Carrying value of VIE	$ 25.2
Real Estate Debt Investments
Period past due for suspension of income recognition	90 days
PE Investment I
Investments in and advances to unconsolidated ventures
Number of significant unconsolidated joint ventures for which disclosure of summarized financial statement information is required	1

Net carrying amount of the assets and liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), when the reporting entity is not the VIE's primary beneficiary.

No definition available.

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssetsAndLiabilitiesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant