Income Taxes (Significant Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Stock-based compensation expense	$ 518	$ 421
Accrued employee benefits	580	463
Accruals and reserves not currently deductible	1,049	1,047
Tax credits	3,723	3,264
Net operating losses	1,085	771
Operating leases	2,620	1,876
Intangible assets	1,525	164
Other	463	226
Total deferred tax assets	11,563	8,232
Valuation allowance	(4,823)	(3,502)
Total deferred tax assets net of valuation allowance	6,740	4,730
Deferred tax liabilities:
Property and equipment, net	(3,382)	(1,798)
Renewable energy investments	(415)	(466)
Foreign Earnings	(383)	(373)
Net investment gains	(1,901)	(1,074)
Operating leases	(2,354)	(1,619)
Other	(782)	(380)
Total deferred tax liabilities	(9,217)	(5,710)
Net deferred tax assets (liabilities)	$ (2,477)	$ (980)