Non Controlling Interests in The Parent Company Non Contolling Interests in the Parent Company (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 32.3	$ 33.1
Settlement value of non controlling interest in operating partnership	$ 30.5	$ 25.6

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

No definition available.

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