Premiums Receivable and Other Insurance Assets Premiums Receivable and Other Insurance Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Premiums Receivable and Other Insurance Assets [Abstract]
Prepaid Reinsurance Premiums	$ 439	$ 382
Reinsurance Recoverables, Incurred but Not Reported Claims	108	120
Reinsurance Recoverables on Paid Losses, Gross	20	18
Premiums Receivable, Net	80	82
Deferred Policy Acquisition Costs	1,258	1,199
Premiums receivable and other insurance assets	$ 1,905	$ 1,801