Noncontrolling Interests (Property Partnerships) (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Property partnerships	$ 1,599,502	$ 1,602,467

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