Income Taxes (Reconciliation between the Company's federal income tax (expense) benefit at statutory rates and the recorded income tax (expense) benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense at statutory rates	$ (398)	$ (192)	$ (423)
Tax benefit from tax exempt income	124	123	119
Foreign taxes and credits	3	9	(6)
Other tax expense	(7)	(10)	(9)
Income tax (expense) benefit	$ (278)	$ (70)	$ (319)