8. Investing Activities (Details 10) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 Liability [Member]	Dec. 31, 2011 Liability [Member] As restated and amended [Member]	Sep. 30, 2012 Liability [Member] Limited Partnerships [Member]	Dec. 31, 2011 Liability [Member] Limited Partnerships [Member] As restated and amended [Member]	Sep. 30, 2012 Liability [Member] LLCs [Member]	Dec. 31, 2011 Liability [Member] LLCs [Member] As restated and amended [Member]	Sep. 30, 2012 Maximum Exposure of Loss [Member]	Dec. 31, 2011 Maximum Exposure of Loss [Member] As restated and amended [Member]	Sep. 30, 2012 Maximum Exposure of Loss [Member] Limited Partnerships [Member]	Dec. 31, 2011 Maximum Exposure of Loss [Member] Limited Partnerships [Member] As restated and amended [Member]	Dec. 31, 2011 LLCs [Member] As restated and amended [Member]	Sep. 30, 2012 LLCs [Member] Maximum Exposure of Loss [Member]	Sep. 30, 2012 Assets [Member]	Dec. 31, 2011 Assets [Member] As restated and amended [Member]	Sep. 30, 2012 Assets [Member] Limited Partnerships [Member]	Dec. 31, 2011 Assets [Member] Limited Partnerships [Member] As restated and amended [Member]	Sep. 30, 2012 Assets [Member] LLCs [Member]	Dec. 31, 2011 Assets [Member] LLCs [Member] As restated and amended [Member]
Total							$ 195.7	$ 210.1	$ 192.4	$ 201.6	$ 8.5	$ 3.3	$ 128.9	$ 141.7	$ 125.6	$ 133.2	$ 3.3	$ 8.5