Schedule II - Condensed Financial Information, Statements of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities
Shareholders' net income		$ 519	$ 533
Adjustments to reconcile shareholders' net income to net cash provided by (used in) operating activities:
Other liabilities		(263)	157
Other, net	[1]	5	17
Net cash provided by (used in) operating activities	[1]	894	737
Cash Flows from Investing Activities
Short term investments purchased		(198)	(420)
Net cash provided by (used in) investing activities		(333)	(49)
Cash Flows from Financing Activities
Net change in short-term debt		(6)	(5)
Net proceeds on issuance of long-term debt		0	894
Issuance of common stock		10	99
Repurchase of common stock		(139)	(413)
Net cash provided by (used in) financing activities	[1]	(146)	530
Net increase (decrease) in cash and cash equivalents		433	1,200
Cash and cash equivalents, January 1		1,968	1,420
Cash and cash equivalents, March 31		$ 2,401	$ 2,620

[1] As required by the adoption of ASU 2016-09, the Company retrospectively reclassified $73 million of cash payments from operating to financing activities for the three months ended March 31, 2015. These payments were related to employee tax obligations associated with stock compensation. The comparable amount reported in financing activities for the three months ended March 31, 2016 was $67 million. See Note 2 for further discussion.