Consolidated Investment Products (Condensed Consolidating Statement Of Income Line Items Reflecting Impact Of Consolidation Of Investment Products Into The Condensed Consolidated Statements Of Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Total operating revenues	$ 5,147.1	$ 4,644.6	$ 4,050.4
Total operating expenses	3,870.2	3,524.4	3,207.8
Operating Income (Loss)	1,276.9	1,120.2	842.6
Equity in earnings of unconsolidated affiliates	32.8	35.5	29.7
Interest and dividend income	13.1	10.0	9.8
Other gains and losses, net	28.1	2.6	8.3
Interest and dividend income of CIP	206.5	190.0	258.5
Interest expense of CIP	(133.9)	(123.3)	(168.3)
Other gains/(losses) of CIP, net	20.4	61.9	(97.7)
Income from continuing operations before income taxes	1,395.1	1,255.2	830.6
Income tax provision	(390.6)	(336.9)	(261.4)
Income from continuing operations, net of income taxes	1,004.5	918.3	569.2
Income/(loss) from discontinued operations, net of taxes	(3.4)	64.5	18.1
Net income	1,001.1	982.8	587.3
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	(13.0)	(42.5)	89.8
Net income attributable to common shareholders	988.1	940.3	677.1
CLOs - VIEs [Member]
Total operating revenues	0	0	0
Total operating expenses	61.5	65.8	48.2
Operating Income (Loss)	(61.5)	(65.8)	(48.2)
Equity in earnings of unconsolidated affiliates	0	0	0
Interest and dividend income	0	0	0
Other gains and losses, net	0	0	0
Interest and dividend income of CIP	220.4	199.8	260.7
Interest expense of CIP	(151.2)	(138.6)	(182.8)
Other gains/(losses) of CIP, net	(93.2)	3.0	(112.2)
Income from continuing operations before income taxes	(85.5)	(1.6)	(82.5)
Income tax provision	0	0	0
Income from continuing operations, net of income taxes	(85.5)	(1.6)	(82.5)
Income/(loss) from discontinued operations, net of taxes	0	0	0
Net income	(85.5)	(1.6)	(82.5)
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	85.7	1.4	82.2
Net income attributable to common shareholders	0.2	(0.2)	(0.3)
Other VIEs [Member]
Total operating revenues	0.2	0	0
Total operating expenses	1.1	0.8	0.9
Operating Income (Loss)	(0.9)	(0.8)	(0.9)
Equity in earnings of unconsolidated affiliates	0	0	0
Interest and dividend income	0	0	0
Other gains and losses, net	0	0	0
Interest and dividend income of CIP	0	0	0
Interest expense of CIP	0	0	0
Other gains/(losses) of CIP, net	(1.0)	1.7	2.4
Income from continuing operations before income taxes	(1.9)	0.9	1.5
Income tax provision	0	0	0
Income from continuing operations, net of income taxes	(1.9)	0.9	1.5
Income/(loss) from discontinued operations, net of taxes	0	0	0
Net income	(1.9)	0.9	1.5
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	2.2	(0.9)	(1.5)
Net income attributable to common shareholders	0.3	0	0
VOEs [Member]
Total operating revenues	0.4	0.5	0
Total operating expenses	7.8	6.7	23.4
Operating Income (Loss)	(7.4)	(6.2)	(23.4)
Equity in earnings of unconsolidated affiliates	0	0	0
Interest and dividend income	0	0	0
Other gains and losses, net	0	0	0
Interest and dividend income of CIP	0	0	0
Interest expense of CIP	0	0	0
Other gains/(losses) of CIP, net	102.3	54.3	13.7
Income from continuing operations before income taxes	94.9	48.1	(9.7)
Income tax provision	0	0	0
Income from continuing operations, net of income taxes	94.9	48.1	(9.7)
Income/(loss) from discontinued operations, net of taxes	0	0	0
Net income	94.9	48.1	(9.7)
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	(91.2)	(45.2)	9.1
Net income attributable to common shareholders	3.7	2.9	(0.6)
Adjustments [Member]
Total operating revenues	(35.8)	(38.4)	(41.0)
Total operating expenses	(35.8)	(38.4)	(41.0)
Operating Income (Loss)	0	0	0
Equity in earnings of unconsolidated affiliates	(4.0)	(2.5)	0.5
Interest and dividend income	(3.3)	(5.5)	(12.3)
Other gains and losses, net	(4.8)	(11.8)	(8.7)
Interest and dividend income of CIP	(13.9)	(9.8)	(2.2)
Interest expense of CIP	17.3	15.3	14.5
Other gains/(losses) of CIP, net	12.3	2.9	(1.6)
Income from continuing operations before income taxes	3.6	(11.4)	(9.8)
Income tax provision	0	0	0
Income from continuing operations, net of income taxes	3.6	(11.4)	(9.8)
Income/(loss) from discontinued operations, net of taxes	0	0	0
Net income	3.6	(11.4)	(9.8)
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	0	0	0
Net income attributable to common shareholders	3.6	(11.4)	(9.8)
Impact of CIP [Member]
Total operating revenues	(35.2)	(37.9)	(41.0)
Total operating expenses	34.6	34.9	31.5
Operating Income (Loss)	(69.8)	(72.8)	(72.5)
Equity in earnings of unconsolidated affiliates	(4.0)	(2.5)	0.5
Interest and dividend income	(3.3)	(5.5)	(12.3)
Other gains and losses, net	(4.8)	(11.8)	(8.7)
Interest and dividend income of CIP	206.5	190.0	258.5
Interest expense of CIP	(133.9)	(123.3)	(168.3)
Other gains/(losses) of CIP, net	20.4	61.9	(97.7)
Income from continuing operations before income taxes	11.1	36.0	(100.5)
Income tax provision	0	0	0
Income from continuing operations, net of income taxes	11.1	36.0	(100.5)
Income/(loss) from discontinued operations, net of taxes	0	0	0
Net income	11.1	36.0	(100.5)
(Gains)/losses attributable to noncontrolling interests in consolidated entities, net	(3.3)	(44.7)	89.8
Net income attributable to common shareholders	$ 7.8	$ (8.7)	$ (10.7)