Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement of Cash Flows [Abstract]
Net income (loss)	$ 75.1	$ 144.0
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net cash provided by operating activities	282.8	324.3
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	1,193.7	1,435.4
Equity securities, available-for-sale	0.4	1.1
Mortgage loans on real estate	30.8	105.0
Limited partnerships/corporations	6.0	18.1
Acquisition of:
Fixed maturities	(1,497.7)	(1,255.0)
Equity securities, available-for-sale	(0.2)	(0.7)
Mortgage loans on real estate	(218.8)	(322.1)
Limited partnerships/corporations	(2.2)	(18.8)
Derivatives, net	(55.8)	(1.1)
Policy loans, net	3.3	5.1
Short-term investments, net	493.8	(121.3)
Loan-Dutch State obligation, net	0	24.2
Collateral received	(25.2)	(11.7)
Purchases of fixed assets, net	(0.2)	0
Net cash used in investing activities	(72.1)	(141.8)
Cash Flows from Financing Activities:
Deposits received for investment contracts	561.4	577.4
Maturities and withdrawals from investment contracts	(660.8)	(617.2)
Short-term repayments of repurchase agreements, net	0	(48.5)
Net cash provided by (used in) financing activities	(99.4)	(88.3)
Net increase (decrease) in cash and cash equivalents	111.3	94.2
Cash and cash equivalents, beginning of year	363.4	217.1
Cash and cash equivalents, end of year	$ 474.7	$ 311.3