Quarterly Supplementary Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 2,694	$ 2,227	$ 2,714	$ (99)	$ 2,152	$ 1,700	$ 1,913	$ 2,159	$ 7,536	$ 7,924	$ 5,407
Income (loss) before income taxes	1,316	614	1,145	(1,576)	781	294	530	867	1,499	2,472	251
Net Income (Loss) Attributable to Parent	$ 1,049	$ 484	$ 909	$ (1,226)	$ 626	$ 248	$ 428	$ 695	$ 1,216	$ 1,997	$ 287
Basic (in usd per share)	$ 6.52	$ 3.01	$ 5.65	$ (7.56)	$ 3.84	$ 1.51	$ 2.62	$ 4.27	$ 7.55	$ 12.24	$ 1.76
Diluted (in usd per share)	$ 6.47	$ 2.99	$ 5.63	$ (7.56)	$ 3.79	$ 1.49	$ 2.59	$ 4.22	$ 7.49	$ 12.10	$ 1.75