Consolidated Comprehensive Income Statement (unaudited) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 943	$ 1,027	$ 944	$ 2,902	$ 2,871
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments		(202)	51	331	(301)	77
Unrealized (loss) gain on assets available-for-sale:
Unrealized (loss) gain arising during the period		(150)	77	233	(776)	1,169
Reclassification adjustment		(2)	(1)	(6)	(3)	(20)
Total unrealized (loss) gain on assets available-for-sale		(152)	76	227	(779)	1,149
Defined benefit plans:
Amortization of prior service credit, net loss and initial obligation included in net periodic benefit cost		22	25	20	69	57
Total defined benefit plans		22	25	20	69	57
Net unrealized (loss) gain on cash flow hedges		(1)	(3)	8	(7)	1
Total other comprehensive (loss) income, net of tax	[1]	(333)	149	586	(1,018)	1,284
Total comprehensive income		610	1,176	1,530	1,884	4,155
Net loss (income) attributable to noncontrolling interests		4	(5)	(7)	(6)	(4)
Other comprehensive loss attributable to noncontrolling interests		0	0	(2)	0	0
Comprehensive income applicable to shareholders of The Bank of New York Mellon Corporation		$ 614	$ 1,171	$ 1,521	$ 1,878	$ 4,151

[1] Other comprehensive (loss) income attributable to The Bank of New York Mellon Corporation shareholders was $(333) million for the quarter ended Sept. 30, 2021, $149 million for the quarter ended June 30, 2021, $584 million for the quarter ended Sept. 30, 2020, $(1,018) million for the nine months ended Sept. 30, 2021 and $1,284 million for the nine months ended Sept. 30, 2020.