Quarterly Supplementary Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 2,152	$ 1,700	$ 1,913	$ 2,159	$ 710	$ 1,915	$ 1,558	$ 1,224	$ 7,924	$ 5,407	$ 5,732
Income before income taxes	781	294	530	867	(581)	618	264	(50)	2,472	251	730
Net Income (Loss) Attributable to Parent	$ 626	$ 248	$ 428	$ 695	$ (452)	$ 553	$ 217	$ (31)	$ 1,997	$ 287	$ 1,045
Basic (in usd per share)	$ 3.84	$ 1.51	$ 2.62	$ 4.27	$ (2.78)	$ 3.40	$ 1.33	$ (0.19)	$ 12.24	$ 1.76	$ 6.36
Diluted (in usd per share)	$ 3.79	$ 1.49	$ 2.59	$ 4.22	$ (2.78)	$ 3.38	$ 1.32	$ (0.19)	$ 12.10	$ 1.75	$ 6.29