Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 209.7	$ 282.8
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	724.4	1,193.7
Equity securities, available-for-sale	9.5	0.4
Mortgage loans on real estate	91.5	30.8
Limited partnerships/corporations	14.0	6.0
Acquisition of:
Fixed maturities	(756.8)	(1,497.7)
Equity securities, available-for-sale	0	(0.2)
Mortgage loans on real estate	(72.4)	(218.8)
Limited partnerships/corporations	(2.6)	(2.2)
Derivatives, net	2.1	(55.8)
Policy loans, net	1.3	3.3
Short-term investments, net	(95.0)	493.8
Collateral received	69.5	(25.2)
Purchases of fixed assets, net	0	(0.2)
Net cash used in investing activities	(14.5)	(72.1)
Cash Flows from Financing Activities:
Deposits received for investment contracts	861.6	561.4
Maturities and withdrawals from investment contracts	(898.3)	(660.8)
Short-term loans to affiliates, net	(72.0)	0
Net cash provided by (used in) financing activities	(108.7)	(99.4)
Net increase (decrease) in cash and cash equivalents	86.5	111.3
Cash and cash equivalents, beginning of year	378.9	363.4
Cash and cash equivalents, end of year	$ 465.4	$ 474.7