Segments (Operating Revenues) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Total operating revenues	$ 2,195.4	$ 2,090.5
Closed Block Variable Annuity	284.6	(444.0)
Net realized investment gains (losses) and related charges and adjustments	49.6	30.4
Gain (loss) on change in fair value of derivatives related to guaranteed benefits	(23.9)	20.6
Revenues related to businesses exited through reinsurance or divestment	19.0	(12.1)
Revenues (loss) attributable to noncontrolling interests	60.8	40.3
Other adjustments to operating revenues	85.4	92.9
Total revenues	2,670.9	1,818.6
Intersegment
Segment Reporting Information [Line Items]
Total operating revenues	39.3	39.3
Retirement Solutions | Retirement
Segment Reporting Information [Line Items]
Total operating revenues	598.5	583.2
Retirement Solutions | Annuities
Segment Reporting Information [Line Items]
Total operating revenues	354.4	307.6
Investment Management
Segment Reporting Information [Line Items]
Total operating revenues	160.5	131.9
Insurance Solutions | Individual Life
Segment Reporting Information [Line Items]
Total operating revenues	692.2	687.1
Insurance Solutions | Employee Benefits
Segment Reporting Information [Line Items]
Total operating revenues	338.9	318.1
Total Ongoing Businesses
Segment Reporting Information [Line Items]
Total operating revenues	2,144.5	2,027.9
Corporate
Segment Reporting Information [Line Items]
Total operating revenues	25.3	17.1
Closed Blocks
Segment Reporting Information [Line Items]
Total operating revenues	25.6	45.5
Closed Blocks | Closed Block Institutional Spread Products
Segment Reporting Information [Line Items]
Total operating revenues	17.6	38.3
Closed Blocks | Closed Block Other
Segment Reporting Information [Line Items]
Total operating revenues	$ 8.0	$ 7.2