Other comprehensive income (loss) - Components (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pre-tax amount
Total other comprehensive income (loss), Pre-tax amount		$ 1,114	$ (21)	$ 420	$ 1,093	$ 777
Tax (expense) benefit
Total other comprehensive income (loss), Tax (expense) benefit		(230)	(165)	(118)	(395)	(202)
After-tax amount
Total other comprehensive income (loss), net of tax	[1]	884	(186)	302	698	575
Foreign currency translation
Pre-tax amount
Other comprehensive income (loss), Pre-tax amount		104	(265)	29	(161)	56
Total other comprehensive income (loss), Pre-tax amount		104	(265)	29	(161)	56
Tax (expense) benefit
Other comprehensive income (loss), Tax (expense) benefit		11	(104)	(19)	(93)	(17)
Total other comprehensive income (loss), Tax (expense) benefit		11	(104)	(19)	(93)	(17)
After-tax amount
Other comprehensive income (loss), After-tax amount		115	(369)	10	(254)	39
Total other comprehensive income (loss), net of tax		115	(369)	10	(254)	39
Unrealized gain (loss) on assets available-for-sale
Pre-tax amount
Other comprehensive income (loss), Pre-tax amount		989	243	384	1,232	706
Reclassification adjustment, Pre-tax amount		(9)	(9)	(7)	(18)	(8)
Total other comprehensive income (loss), Pre-tax amount		980	234	377	1,214	698
Tax (expense) benefit
Other comprehensive income (loss), Tax (expense) benefit		(236)	(60)	(97)	(296)	(180)
Reclassification adjustment, Tax (expense) benefit		2	2	2	4	2
Total other comprehensive income (loss), Tax (expense) benefit		(234)	(58)	(95)	(292)	(178)
After-tax amount
Other comprehensive income (loss), After-tax amount		753	183	287	936	526
Reclassification adjustment, After-tax amount		(7)	(7)	(5)	(14)	(6)
Total other comprehensive income (loss), net of tax		746	176	282	922	520
Defined benefit plans
Pre-tax amount
Other comprehensive income (loss), Pre-tax amount					0	(11)
Reclassification adjustment, Pre-tax amount		24	24	12	48	25
Total other comprehensive income (loss), Pre-tax amount		24	24	12	48	14
Tax (expense) benefit
Other comprehensive income (loss), Tax (expense) benefit					0	2
Reclassification adjustment, Tax (expense) benefit		(5)	(6)	(2)	(11)	(5)
Total other comprehensive income (loss), Tax (expense) benefit		(5)	(6)	(2)	(11)	(3)
After-tax amount
Other comprehensive income (loss), After-tax amount					0	(9)
Reclassification adjustment, After-tax amount		19	18	10	37	20
Total other comprehensive income (loss), net of tax		19	18	10	37	11
Unrealized gain (loss) on cash flow hedges
Pre-tax amount
Other comprehensive income (loss), Pre-tax amount		3	(13)	2	(10)	8
Reclassification adjustment, Pre-tax amount		3	(1)	0	2	1
Total other comprehensive income (loss), Pre-tax amount		6	(14)	2	(8)	9
Tax (expense) benefit
Other comprehensive income (loss), Tax (expense) benefit		(1)	3	(2)	2	(6)
Reclassification adjustment, Tax (expense) benefit		(1)	0	0	(1)	2
Total other comprehensive income (loss), Tax (expense) benefit		(2)	3	(2)	1	(4)
After-tax amount
Other comprehensive income (loss), After-tax amount		2	(10)	0	(8)	2
Reclassification adjustment, After-tax amount		2	(1)	0	1	3
Total other comprehensive income (loss), net of tax		4	(11)	0	(7)	5
Unrealized gain (loss) on cash flow hedges | Staff expense
Pre-tax amount
Reclassification adjustment, Pre-tax amount		3	(1)	0	2	1
Tax (expense) benefit
Reclassification adjustment, Tax (expense) benefit		(1)	0	0	(1)	2
After-tax amount
Reclassification adjustment, After-tax amount		$ 2	$ (1)	$ 0	$ 1	$ 3

[1] Other comprehensive income (loss) attributable to The Bank of New York Mellon Corporation shareholders was $884 million for the quarter ended June 30, 2020, $(184) million for the quarter ended March 31, 2020, $302 million for the quarter ended June 30, 2019, $700 million for the six months ended June 30, 2020 and $573 million for the six months ended June 30, 2019.