Legal Proceedings - 10-K (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) mortgage_loan
Legal Reserve | Maximum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued		$ 100.0
Interchange Litigation
Loss Contingencies [Line Items]
Litigation Settlement Amount		6,600.0
Fulton Financial Advisors NA V PNC Capital Markets LLC | PNC Capital Markets Llc
Loss Contingencies [Line Items]
Purchase Of Auction Rate Certificates		123.0
Fulton Financial Advisors NA V PNC Capital Markets LLC | National City Corporation
Loss Contingencies [Line Items]
Purchase Of Auction Rate Certificates		175.0
White Et Al V The PNC Financial Services Group
Loss Contingencies [Line Items]
Private Mortgage Insurance Premiums		219.0
Paid Claims Supporting Captive Reinsurance Arrangements		12.0
Residential Funding Company LLC V Pnc Bank
Loss Contingencies [Line Items]
Residential Mortgage Loans Sold Allegedly Materially Defective		$ 6,500.0
ResCap Liquidating Trust v PNC Bank
Loss Contingencies [Line Items]
Residential Mortgage Loans Sold | mortgage_loan		21,300
Bankruptcy Mortgage Loans Sold Prinicipal Balance		$ 789.0
Jo Ann Howard Pc Et Al V Cassity Et Al
Loss Contingencies [Line Items]
Alleged Present And Future Losses		600.0
Compensatory damages		356.0
Punitive Damages		36.0
Prejudgement Interests		179.0
Reduced Compensatory Damages		289.0
DD Growth Premium Master Fund
Loss Contingencies [Line Items]
Alleged Claims For Loss In Net Asset Value Of Fund		283.0
Alleged Claims For Certain Subscriptions Paid Into Fund		$ 134.0
Subsequent Event | Federal Reserve Termination of Consent Order
Loss Contingencies [Line Items]
Civil money penalty assessed	$ 3.5