Business Dispositions Level 4 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Mar. 31, 2017
Other assets	$ 1,786	$ 1,839
Disposal Group, Including Discontinued Operation, Assets, Current	870	923
Disposal Group, Including Discontinued Operation, Liabilities, Current	611	661
P&C Runoff Subsidiaries [Member]
Investments and Cash	657	657
Disposal Group, Including Discontinued Operation, Consideration		262
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	213	266
Disposal Group, Including Discontinued Operation, Assets, Current	870	923
Disposal Group, Including Discontinued Operation, Liabilities	600	646
Disposal Group, Including Discontinued Operation, Other Liabilities	11	15
Disposal Group, Including Discontinued Operation, Liabilities, Current	611	661
HFPI estimated after tax loss	5
Accounts Receivable [Member] | P&C Runoff Subsidiaries [Member]
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	$ 0	$ 69