Consolidated Investment Products (VIE Balance Sheets Consolidated In Period) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	$ 404.0	$ 583.6
Accounts receivable and other assets of CIP	161.3	58.3
Investments of CIP	5,762.8	4,734.7
Total assets	20,462.5	19,270.5
Debt of CIP	5,149.6	4,181.7
Other liabilities of CIP	280.9	461.8
Total liabilities	11,177.2	10,293.2
Total equity	9,119.8	8,977.3	9,049.0	9,137.6
Total liabilities and equity	20,462.5	19,270.5
CLOs - VIEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	378.8	542.3
Investments of CIP	5,063.5	4,237.3
Total assets	5,598.0	4,835.9
Debt of CIP	5,302.9	4,270.4
Other liabilities of CIP	277.4	461.4
Total liabilities	5,580.3	4,731.8
Total liabilities and equity	5,598.0	4,835.9
VOEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	21.5	35.7
Investments of CIP	730.2	512.2
Total assets	757.2	549.7
Debt of CIP	0	0
Other liabilities of CIP	6.9	3.0
Total liabilities	6.9	3.0
Total liabilities and equity	757.2	549.7
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | CLOs - VIEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	30.5	1.9
Accounts receivable and other assets of CIP	17.6	4.2
Investments of CIP	346.5	260.5
Total assets	394.6	266.6
Debt of CIP	347.9	241.1
Other liabilities of CIP	45.7	2.4
Total liabilities	393.6	243.5
Total equity	1.0	23.1
Total liabilities and equity	394.6	266.6
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | VOEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP		6.6
Accounts receivable and other assets of CIP		12.1
Investments of CIP		76.1
Total assets		94.8
Debt of CIP		25.0
Other liabilities of CIP		36.0
Total liabilities		61.0
Total equity		33.8
Total liabilities and equity		94.8
New CLO [Member] | CLOs - VIEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	816.5	967.3
Accounts receivable and other assets of CIP	11.3	13.5
Investments of CIP	1,751.4	1,091.9
Total assets	2,579.2	2,072.7
Debt of CIP	1,913.7	1,346.5
Other liabilities of CIP	674.7	728.7
Total liabilities	2,588.4	2,075.2
Total equity	(9.2)	(2.5)
Total liabilities and equity	2,579.2	2,072.7
New CLO [Member] | VOEs [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents of CIP	0	6.6
Accounts receivable and other assets of CIP	9.0	2.6
Investments of CIP	40.1	52.2
Total assets	49.1	61.4
Debt of CIP	0	25.0
Other liabilities of CIP	11.8	36.0
Total liabilities	11.8	61.0
Total equity	37.3	0.4
Total liabilities and equity	$ 49.1	$ 61.4