Schedule II - Condensed Financial Information, Statements of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Cash Flows from Operating Activities
Shareholders' net income		$ 456	$ 547	$ 1,485	$ 1,668
Adjustments to reconcile shareholders' net income to net cash provided by (used in) operating activities:
Loss on extinguishment of debt				0	100
Other liabilities				9	219
Other, net	[1]			25	(4)
Net cash provided by (used in) operating activities	[1]			3,074	1,797
Cash Flows from Investing Activities
Short term investments purchased				(1,317)	(689)
Other, net				(101)	0
Net cash provided by (used in) investing activities				(1,589)	(297)
Cash Flows from Financing Activities
Net change in short-term debt				(143)	(15)
Net proceeds on issuance of long-term debt				0	894
Repayment of long-term debt				0	(938)
Issuance of common stock				23	136
Repurchase of common stock				(139)	(536)
Net cash provided by (used in) financing activities	[1]			(255)	(503)
Net increase (decrease) in cash and cash equivalents				1,256	961
Cash and cash equivalents, January 1				1,968	1,420
Cash and cash equivalents, September 30		$ 3,224	$ 2,381	$ 3,224	$ 2,381

[1] As required by the adoption of ASU 2016-09, the Company retrospectively reclassified $78 million of cash payments from operating to financing activities for the nine months ended September 30, 2015. These payments were related to employee tax obligations associated with stock compensation. The comparable amount reported in financing activities for the nine months ended September 30, 2016 was $69 million. See Note 2 for further discussion.