Variable Interest Entities (Balances Related to Joint Ventures) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012 entities
Variable Interest Entities [Abstract]
Number of Unconsolidated Joint Ventures Considered Variable Interest Entities	4
Carrying Value of Investment in Unconsolidated Companies	$ 59.2
Maximum Loss Exposure from Investment in Unconsolidated Companies	59.2
Carrying Value of Guarantee Obligations	(20.9)	[1]
Maximum Loss Exposure from Guarantee Obligations	$ (146.7)	[1]

[1] We are party to guarantees of the third-party debt of these joint ventures and our maximum loss exposure is equal to the maximum monetary obligation pursuant to the guarantee agreements. We have also recorded a liability for our probable future obligation under a guarantee to the lender of one of these ventures, which is included within the carrying value of our guarantee obligations. Pursuant to an agreement with the lender, we may make partner loans to this joint venture that will reduce our maximum guarantee obligation on a dollar-for-dollar basis. The carrying value of our recorded guarantee obligations is included in other liabilities in our Consolidated Balance Sheets.