Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income	$ 13,323	$ 11,862	$ 22,922
Unrealized gains (losses) on marketable securities, net of deferred taxes	3	1	(42)
Deferred gains (losses) on cash flow hedges, net of deferred taxes	19	50	60
Amounts reclassified to net income:
Realized (gains) losses on marketable securities, net of deferred taxes	0	0	(1)
Realized (gains) losses on cash flow hedges, net of deferred taxes	65	(6)	(37)
Employee benefit obligations, net of deferred taxes	(60)	7	41
Currency translation adjustments, net of deferred taxes	1,375	(916)	147
Comprehensive income	14,725	10,998	23,090
Less: Net income attributable to noncontrolling interests and redeemable subsidiary preferred stock	266	131	187
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(13)	(41)	81
Comprehensive income attributable to Comcast Corporation	14,472	10,908	22,822
NBCUniversal Media LLC [Member]
Net income	5,964	5,305	5,214
Unrealized gains (losses) on marketable securities, net of deferred taxes	0	0	(233)
Deferred gains (losses) on cash flow hedges, net of deferred taxes	(5)	3	(13)
Amounts reclassified to net income:
Employee benefit obligations, net of deferred taxes	(53)	14	112
Currency translation adjustments, net of deferred taxes	6	(16)	189
Comprehensive income	5,912	5,306	5,269
Less: Net income attributable to noncontrolling interests	180	68	134
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(12)	(41)	81
Comprehensive income attributable to Comcast Corporation	$ 5,744	$ 5,279	$ 5,054