Basis of Presentation and Summary of Significant Accounting Policies - Noncontrolling Interests in Consolidated Real Estate Partnerships (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Noncontrolling interests in consolidated real estate partnerships	$ 233,296	$ 233,008
Napico Portfolio [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interests in consolidated real estate partnerships	$ 44,106	$ 35,818

Carrying amount of the equity interests owned by noncontrolling partners of a limited partnership included in the entity's consolidated financial statements.

No definition available.

Name:	us-gaap_MinorityInterestInLimitedPartnerships
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant