Employee Benefit Plans (Reconciliation of Changes in Projected Benefit Obligation and Change in Plan Assets) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
PNC Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation at end of year		$ 4,726,000,000	$ 4,495,000,000
Projected benefit obligation at beginning of year		4,547,000,000	4,397,000,000
Service cost		160,000,000	102,000,000	$ 107,000,000
Interest cost		179,000,000	186,000,000	177,000,000
Amendments		17,000,000
Actuarial (gains)/losses and changes in assumptions		172,000,000	131,000,000
Benefits paid		(286,000,000)	(269,000,000)
Projected benefit obligation at end of year		4,789,000,000	4,547,000,000	4,397,000,000
Fair value of plan assets, beginning balance		4,617,000,000	4,316,000,000
Actual return on plan assets		722,000,000	320,000,000
Employer contribution	$ 200,000,000	200,000,000	250,000,000
Benefits paid		(286,000,000)	(269,000,000)
Fair value of plan assets, end balance		5,253,000,000	4,617,000,000	4,316,000,000
Funded status		464,000,000	70,000,000
Noncurrent asset		464,000,000	70,000,000
Net amount recognized on the consolidated balance sheet		464,000,000	70,000,000
Prior service cost (credit)		13,000,000	(7,000,000)
Net actuarial loss		534,000,000	841,000,000
Amount recognized in AOCI		547,000,000	834,000,000
Nonqualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation at end of year		280,000,000	282,000,000
Projected benefit obligation at beginning of year		289,000,000	298,000,000
Service cost		3,000,000	3,000,000	3,000,000
Interest cost		10,000,000	12,000,000	11,000,000
Actuarial (gains)/losses and changes in assumptions		8,000,000	7,000,000
Benefits paid		(24,000,000)	(31,000,000)
Projected benefit obligation at end of year		286,000,000	289,000,000	298,000,000
Employer contribution		24,000,000	31,000,000
Benefits paid		(24,000,000)	(31,000,000)
Funded status		(286,000,000)	(289,000,000)
Current liability		(28,000,000)	(27,000,000)
Noncurrent liability		(258,000,000)	(262,000,000)
Net amount recognized on the consolidated balance sheet		(286,000,000)	(289,000,000)
Net actuarial loss		77,000,000	74,000,000
Amount recognized in AOCI		77,000,000	74,000,000
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of year		373,000,000	368,000,000
Service cost		5,000,000	6,000,000	5,000,000
Interest cost		14,000,000	15,000,000	15,000,000
Amendments		2,000,000
Actuarial (gains)/losses and changes in assumptions		(18,000,000)	6,000,000
Participant contributions		3,000,000	4,000,000
Federal Medicare subsidy on benefits paid		1,000,000	1,000,000
Benefits paid		(25,000,000)	(27,000,000)
Projected benefit obligation at end of year		355,000,000	373,000,000	368,000,000
Fair value of plan assets, beginning balance		208,000,000	200,000,000
Actual return on plan assets		9,000,000	(7,000,000)
Employer contribution		34,000,000	37,000,000
Participant contributions		3,000,000	4,000,000
Federal Medicare subsidy on benefits paid		1,000,000	1,000,000
Benefits paid		(25,000,000)	(27,000,000)
Fair value of plan assets, end balance		230,000,000	208,000,000	$ 200,000,000
Funded status		(125,000,000)	(165,000,000)
Current liability		(2,000,000)	(2,000,000)
Noncurrent liability		(123,000,000)	(163,000,000)
Net amount recognized on the consolidated balance sheet		(125,000,000)	(165,000,000)
Prior service cost (credit)		1,000,000	(3,000,000)
Net actuarial loss		18,000,000	40,000,000
Amount recognized in AOCI		$ 19,000,000	$ 37,000,000