Fair Value Of Financial Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Jan. 18, 2012	Dec. 31, 2011
Recently Adopted Accounting Guidance
Fair Value Level Into Level 3 Transfers Amount		$ 2.7
Transfers of financial assets from level 2 to level 1	6.2	10.2
Fair Value Level One To Level Two Transfers Amount	3.0	17.1
General and limited partnership interests in investment partnerships	21.4	21.4
Direct investments in private equity companies held by private equity funds	13.1	13.1
Commitments Investments In Affiliated And Unaffiliated Partnerships	3.3	3.3		4.0
Stated interest rate	6.70%	6.70%	6.70%
Transfers of financial assets from Level 3	$ 3.1	$ 7.4