Schedule II - Condensed Financial Information, Statements of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities
Shareholders' net income		$ 510	$ 588	$ 1,029	$ 1,121
Adjustments to reconcile shareholders' net income to net cash provided by (used in) operating activities:
Loss on extinguishment of debt			100	0	100
Other liabilities				(58)	216
Other, net	[1]			48	24
Net cash provided by (used in) operating activities	[1]			1,196	1,183
Cash Flows from Investing Activities
Short term investments purchased				(401)	(541)
Net cash provided by (used in) investing activities				(501)	(96)
Cash Flows from Financing Activities
Net change in short-term debt				(111)	(10)
Net proceeds on issuance of long-term debt				0	894
Repayment of long-term debt				0	(938)
Issuance of common stock				14	128
Repurchase of common stock				(139)	(536)
Net cash provided by (used in) financing activities	[1]			(223)	(520)
Net increase (decrease) in cash and cash equivalents				486	549
Cash and cash equivalents, January 1				1,968	1,420
Cash and cash equivalents, June 30		$ 2,454	$ 1,969	$ 2,454	$ 1,969

[1] As required by the adoption of ASU 2016-09, the Company retrospectively reclassified $74 million of cash payments from operating to financing activities for the six months ended June 30, 2015. These payments were related to employee tax obligations associated with stock compensation. The comparable amount reported in financing activities for the six months ended June 30, 2016 was $68 million. See Note 2 for further discussion.