Segment Information (Detail) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Number of operating segments of the Company			three
P AndC Segment [Member]
Segment Reporting Information Structured Products, Interest Income	$ 18.4	$ 17.2	$ 38.1	$ 36.9
Segment Reporting Information Structured Products, Interest Expense	13.5	9.9	25.7	21.4
Segment Reporting Information Structured Products Operating Income Expenses		1.4		1.3
Corporate [Member]
Segment Reporting Information Structured Products, Interest Income		4.7		9.0
Segment Reporting Information Structured Products, Interest Expense		0.7		1.3
Segment Reporting Information Structured Products Operating Expenses		$ 0.9		$ 0.9