Schedule IV - Reinsurance (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reinsurance information
Gross amount	$ 3,524.8	$ 3,554.1	$ 3,205.6
Ceded to other companies	373.2	337.3	317.6
Assumed from other companies	2.5	2.6	3.0
Life insurance in force
Reinsurance information
Gross amount	317,154.5	286,435.3	256,880.3
Ceded to other companies	144,024.9	115,315.7	94,839.7
Assumed from other companies	1,455.4	1,606.2	1,814.9
Net amount	174,585.0	172,725.8	163,855.5
Percentage of amount assumed to net (as a percent)	0.80%	0.90%	1.10%
Premiums
Reinsurance information
Gross amount	3,524.8	3,554.1	3,205.6
Ceded to other companies	373.2	337.3	317.6
Assumed from other companies	2.5	2.6	3.0
Net amount	3,154.1	3,219.4	2,891.0
Percentage of amount assumed to net (as a percent)	0.10%	0.10%	0.10%
Life insurance premiums
Reinsurance information
Gross amount	2,216.9	2,289.4	1,490.8
Ceded to other companies	205.2	174.4	158.5
Assumed from other companies	2.5	2.6	3.0
Net amount	2,014.2	2,117.6	1,335.3
Percentage of amount assumed to net (as a percent)	0.10%	0.10%	0.20%
Accident and health insurance premiums
Reinsurance information
Gross amount	1,307.9	1,264.7	1,714.8
Ceded to other companies	168.0	162.9	159.1
Net amount	$ 1,139.9	$ 1,101.8	$ 1,555.7