Employee and Agent Benefits (Details 8) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Qualified defined contribution plan
Defined Contribution Plan Disclosures
Maximum amount of compensation eligible participants could contribute to defined contribution plans	$ 16,500
Amount contributed by the employer to defined contribution plans	36,300,000	35,700,000	33,900,000
Qualified defined contribution plan | Grandfathered Choice Participant
Defined Contribution Plan Disclosures
Eligibility age to be able to elect to retain benefits in defined contribution plan (in years)	47
Minimum years of service to be able to elect to retain benefits in defined contribution plan (in years)	10
Contribution rate of employer to match participant's contributions (as a percent)	50.00%
Maximum percent of participant's compensation matched by employer (as a percent)	3.00%
Qualified defined contribution plan | All other participants
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	75.00%
Maximum percent of participant's compensation matched by employer (as a percent)	6.00%
Nonqualified deferred compensation plan
Defined Contribution Plan Disclosures
Amount contributed by the employer to defined contribution plans	$ 3,500,000	$ 2,800,000	$ 4,600,000
Nonqualified deferred compensation plan | Grandfathered Choice Participant
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	50.00%
Maximum percent of participant's compensation matched by employer (as a percent)	3.00%
Nonqualified deferred compensation plan | All other participants
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	75.00%
Maximum percent of participant's compensation matched by employer (as a percent)	6.00%