v3.20.4
Capital Stock - Common and Preferred Shares Issued and Outstanding and Related Activity (Detail) - shares
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Common Stock [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 171,252,185 171,252,185 171,252,185
Shares repurchased 0 0 0
Net issuance of common shares related to employee stock transactions 0 0 0
PNC LTIP capital contribution   0 0
Exchange of preferred shares series B for common shares 823,188    
Shares, ending balance 172,075,373 171,252,185 171,252,185
Common Stock [Member] | Shares Outstanding [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 154,375,780 157,553,501 159,977,115
Shares repurchased (3,445,554) (4,018,905) (3,511,603)
Net issuance of common shares related to employee stock transactions 779,471 841,184 1,087,989
PNC LTIP capital contribution   0 0
Exchange of preferred shares series B for common shares 823,188    
Shares, ending balance 152,532,885 154,375,780 157,553,501
Treasury Stock Common [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance (16,876,405) (13,698,684) (11,275,070)
Shares repurchased (3,445,554) (4,018,905) (3,511,603)
Net issuance of common shares related to employee stock transactions 779,471 841,184 1,087,989
PNC LTIP capital contribution   0 0
Exchange of preferred shares series B for common shares 0    
Shares, ending balance (19,542,488) (16,876,405) (13,698,684)
Series B Nonvoting Participating Preferred Stock [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 823,188 823,188 823,188
Shares repurchased 0 0 0
Net issuance of common shares related to employee stock transactions 0 0 0
PNC LTIP capital contribution   0 0
Exchange of preferred shares series B for common shares (823,188)    
Shares, ending balance 0 823,188 823,188
Series B Nonvoting Participating Preferred Stock [Member] | Shares Outstanding [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 823,188 823,188 823,188
Shares repurchased 0 0 0
Net issuance of common shares related to employee stock transactions 0 0 0
PNC LTIP capital contribution   0 0
Exchange of preferred shares series B for common shares (823,188)    
Shares, ending balance 0 823,188 823,188
Series C Nonvoting Participating Preferred Stock [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 0 143,458 246,522
Shares repurchased 0 0 0
Net issuance of common shares related to employee stock transactions 0 0 0
PNC LTIP capital contribution   (143,458) (103,064)
Exchange of preferred shares series B for common shares 0    
Shares, ending balance 0 0 143,458
Series C Nonvoting Participating Preferred Stock [Member] | Shares Outstanding [Member]      
Schedule of Capitalization, Equity [Line Items]      
Shares, beginning balance 0 143,458 246,522
Shares repurchased 0 0 0
Net issuance of common shares related to employee stock transactions 0 0 0
PNC LTIP capital contribution   (143,458) (103,064)
Exchange of preferred shares series B for common shares 0    
Shares, ending balance 0 0 143,458