Financial Derivatives (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Cash and securities held to collateralize net derivative assets	$ 2,300,000,000
Cash and securities pledged to collateralize net derivative liabilities	1,900,000,000
Aggregate fair value of all derivative instruments with credit-risk-related contingent features	1,600,000,000
Collateral posted on derivative instruments with credit-risk-related contingent features	1,400,000,000
Maximum amount of collateral PNC would have been required to post if the credit-risk-related contingent features underlying these agreements had been triggered	200,000,000
Risk Participation Agreements Sold
Derivative [Line Items]
Derivative liability, notional amount	7,000,000,000.0	$ 8,000,000,000.0
Credit derivative, maximum exposure, undiscounted	500,000,000	300,000,000
Cash Flow Hedging | Interest Rate Contract
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months	276,000,000
Cash flow hedge gain (loss) to be reclassified within twelve months, net of tax	$ 213,000,000
Maximum length of time over which forecasted loan cash flows are hedged	10 years
Net Investment Hedging | Foreign Exchange Contract
Derivative [Line Items]
Gain (loss) from components excluded from assessment of net investment hedge effectiveness net	$ 0	0	$ 0
Derivative instruments, gain (loss) reclassified from accumulated oci into income, effective portion, net	$ (24,000,000)	$ (24,000,000)	$ 76,000,000