Schedule II - Condensed Financial Information, Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 24,032	$ 2,972	$ 3,656	$ 3,185
Short-term investments	102	199
Other assets	2,227	2,316
Total assets	82,956	61,759
Liabilities:
Short-term debt	9	240
Long-term debt	25,041	5,199
Total liabilities	67,371	47,999
Shareholders Equity:
Common stock (shares issued, 296; authorized, 600)	74	74
Additional paid-in capital	2,985	2,940
Accumulated other comprehensive loss	(1,857)	(1,082)
Retained earnings	18,474	15,800
Less: treasury stock, at cost	(4,121)	(4,021)
Total shareholders' equity	15,555	13,711
Total liabilities and shareholders' equity	$ 82,956	$ 61,759