Consolidated Statements of Income (Unaudited) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenues:
Premiums	$ 119.4	$ 115.5	$ 240.3	$ 234.5
Net investment income	312.2	297.1	622.2	584.0
Policy fees, contract charges, and other	45.9	41.8	90.6	82.3
Net realized investment gains (losses):
Total other-than-temporary impairment losses on securities	(3.1)	(2.7)	(4.0)	(20.6)
Less: portion of losses recognized in other comprehensive income	0.3	1.2	0.3	9.4
Net impairment losses recognized in earnings	(2.8)	(1.5)	(3.7)	(11.2)
Other net realized investment gains (losses)	16.9	(8.5)	33.4	8.0
Total net realized investment gains (losses)	14.1	(10.0)	29.7	(3.2)
Total revenues	491.6	444.4	982.8	897.6
Benefits and expenses:
Policyholder benefits and claims	83.7	83.3	176.0	169.5
Interest credited	225.1	221.5	453.4	440.0
Other underwriting and operating expenses	70.5	64.2	136.5	123.8
Interest expense	8.0	7.9	16.0	15.9
Amortization of deferred policy acquisition costs	20.0	17.0	40.1	32.4
Total benefits and expenses	407.3	393.9	822.0	781.6
Income from operations before income taxes	84.3	50.5	160.8	116.0
Provision (benefit) for income taxes:
Current	31.1	17.4	42.3	27.3
Deferred	(6.2)	(2.7)	4.2	6.6
Total provision for income taxes	24.9	14.7	46.5	33.9
Net income	$ 59.4	$ 35.8	$ 114.3	$ 82.1
Net income per common share:
Basic	$ 0.43	$ 0.26	$ 0.83	$ 0.61
Diluted	$ 0.43	$ 0.26	$ 0.83	$ 0.61
Weighted-average number of common shares outstanding:
Basic	137,523	137,019	137,408	134,035
Diluted	137,532	137,038	137,417	134,056
Cash dividends declared per common share	$ 0.06	$ 0.05	$ 0.11	$ 0.05