Defined Contribution and Deferred Compensation Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined contribution plans [Abstract]
Expense for the 401(k) plans and MPP	$ 70	$ 67	$ 62
Deferred compensation plans [Abstract]
Total liabilities	386	354
Investment held to fund liabilities	146	133
Employees [Member]
Expenses for deferred compensation plans [Abstract]
Employer matching contributions	7	6	6
Increase (decrease) in measurement of liabilities, net of total return swap	7	1	1
Total plan expense (income)	14	7	7
Agents [Member]
Expenses for deferred compensation plans [Abstract]
Employer matching contributions	1	1	3
Increase (decrease) in measurement of liabilities, net of total return swap	2	0	3
Total plan expense (income)	3	1	6
Non Employee Directors [Member]
Expenses for deferred compensation plans [Abstract]
Total plan expense (income)	2	(1)	2
Former Jefferson Pilot Agents [Member]
Expenses for deferred compensation plans [Abstract]
Total plan expense (income)	$ 3	$ 4	$ 2