Defined Contribution and Deferred Compensation Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined contribution plans [Abstract]
Expense for the 401(k) plans and MPP	$ 67	$ 62	$ 63
Deferred compensation plans [Abstract]
Total liabilities	354	363
Investment held to fund liabilities	133	130
Employees [Member]
Expenses for deferred compensation plans [Abstract]
Employer matching contributions	6	6	4
Increase (decrease) in measurement of liabilities, net of total return swap	1	1	(5)
Total plan expense (income)	7	7	(1)
Agents [Member]
Expenses for deferred compensation plans [Abstract]
Employer matching contributions	1	3	1
Increase (decrease) in measurement of liabilities, net of total return swap	0	3	3
Total plan expense (income)	1	6	4
Non-Employee Directors [Member]
Expenses for deferred compensation plans [Abstract]
Total plan expense (income)	(1)	2	1
Former Jefferson-Pilot Agents [Member]
Expenses for deferred compensation plans [Abstract]
Total plan expense (income)	$ 4	$ 2	$ 1