Fair Value Of Financial Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Dec. 31, 2011
Recently Adopted Accounting Guidance
Fair Value Level Into Level 3 Transfers Amount	$ 0.2
Transfers of financial assets from level 2 to level 1	1.8
Fair Value Level One To Level Two Transfers Amount	0.4
Commitments Investments In Affiliated And Unaffiliated Partnerships	$ 3.7	$ 4.0

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Name:	us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant