Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 488.2	$ 572.3
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	1,612.3	1,781.4
Equity securities, available-for-sale	14.1	0.4
Mortgage loans on real estate	218.7	91.4
Limited partnerships/corporations	19.3	13.8
Acquisition of:
Fixed maturities	(1,586.7)	(2,160.3)
Equity securities, available-for-sale	0	(0.3)
Mortgage loans on real estate	(257.0)	(406.8)
Limited partnerships/corporations	(61.0)	(4.1)
Derivatives, net	(2.7)	(101.2)
Policy loans, net	2.4	1.1
Short-term investments, net	0	369.3
Collateral received	102.0	(61.4)
Purchases of fixed assets, net	0	(0.2)
Net cash used in investing activities	61.4	(476.9)
Cash Flows from Financing Activities:
Deposits received for investment contracts	1,083.9	1,251.7
Maturities and withdrawals from investment contracts	(1,317.9)	(1,252.0)
Dividends paid and return of capital distribution	281.0	174.0
Capital contribution from parent	0	0
Net cash provided by (used in) financing activities	(515.0)	(174.3)
Net increase (decrease) in cash and cash equivalents	34.6	(78.9)
Cash and cash equivalents, beginning of year	378.9	363.4
Cash and cash equivalents, end of year	$ 413.5	$ 284.5