Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 241.0	$ 88.9
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	599.4	724.4
Equity securities, available-for-sale	0	9.5
Mortgage loans on real estate	90.8	91.5
Limited partnerships/corporations	5.3	14.0
Acquisition of:
Fixed maturities	(927.8)	(756.8)
Mortgage loans on real estate	(242.8)	(72.4)
Limited partnerships/corporations	(10.4)	(2.6)
Derivatives, net	23.0	2.1
Policy loans, net	4.3	1.3
Short-term investments, net	186.1	(95.0)
Short-term loans to affiliates, net	(150.2)	0
Collateral received	13.2	69.5
Net cash used in investing activities	(409.1)	(14.5)
Cash Flows from Financing Activities:
Deposits received for investment contracts	852.3	861.6
Maturities and withdrawals from investment contracts	(731.1)	(898.3)
Receipts on deposit contracts	0	124.7
Settlements on deposit contracts	(17.3)	(3.9)
Short-term loans to affiliates, net	0	(72.0)
Excess tax benefits on share-based compensation	0.6	0
Net cash provided by financing activities	104.5	12.1
Net (decrease) increase in cash and cash equivalents	(63.6)	86.5
Cash and cash equivalents, beginning of year	481.2	378.9
Cash and cash equivalents, end of year	$ 417.6	$ 465.4