Schedule II - Condensed Financial Information, Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 4,155	$ 3,185	$ 2,401	$ 1,968
Short-term investments	303	691
Other assets	2,250	2,227
Total assets	61,147	59,360
Liabilities:
Short-term debt	142	276
Long-term debt, carrying value	4,621	4,756
Total liabilities	46,862	45,575
Shareholders Equity:
Common stock (shares issued, 296; authorized, 600)	74	74
Additional paid-in capital	2,912	2,892
Accumulated other comprehensive loss	(1,252)	(1,382)
Retained earnings	14,356	13,855
Less: treasury stock, at cost	(1,864)	(1,716)
Total shareholders' equity	14,226	13,723
Total liabilities and equity	$ 61,147	$ 59,360