Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net earnings		$ 4,604	$ 2,659	$ 2,533
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period		286	283	360
Unrealized gains (losses) on investment securities:
Unrealized gains (losses) on investment securities during period		1,731	2,852	(2,534)
Reclassification adjustment for realized (gains) losses on investment securities included in net earnings		2	(53)	(61)
Unrealized gains (losses) on derivatives during period		1	3	0
Pension liability adjustment during period		9	(45)	(20)
Total other comprehensive income (loss) before income taxes		2,029	3,040	(2,255)
Income tax expense (benefit) related to items of other comprehensive income (loss)		631	1,035	(901)
Other comprehensive income (loss), net of income taxes	[1]	1,398	2,005	(1,354)
Total comprehensive income (loss)		$ 6,002	$ 4,664	$ 1,179

[1] All amounts in the table above are net of tax.